2024/05/06 更新

写真a

ミサワ ヒロアキ
三澤 弘明
Misawa Hiroaki
所属
異分野基礎科学研究所 教授(特任)
職名
教授(特任)
ホームページ
外部リンク

学位

  • 理学博士 ( 1984年   筑波大学 )

研究キーワード

  • プラズモンの化学

  • 光化学

研究分野

  • ナノテク・材料 / 基礎物理化学

  • ナノテク・材料 / 応用物理一般

学歴

  • 筑波大学    

    - 1984年

      詳細を見る

    国名: 日本国

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  • 筑波大学    

    - 1982年

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  • 東京都立大学   Faculty of Engineering  

    - 1979年

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    国名: 日本国

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経歴

  • 岡山大学   異分野基礎科学研究所   教授(特任)

    2024年1月 - 現在

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  • 北海道大学   電子科学研究所   研究推進教授

    2023年9月 - 現在

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  • 北海道大学   名誉教授

    2021年4月 - 現在

      詳細を見る

  • 北海道大学   電子科学研究所   特任教授

    2020年4月 - 2023年3月

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  • 北海道大学   電子科学研究所   所長

    2009年10月 - 2013年9月

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  • 北海道大学   電子科学研究所附属ナノテクノロジー研究センター   センター長

    2006年 - 2009年

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  • 北海道大学   電子科学研究所   教授

    2003年5月 - 2020年3月

      詳細を見る

  • 徳島大学   大学院工学研究科   教授

    1997年4月 - 2003年4月

      詳細を見る

  • 徳島大学   工学部   教授

    1995年11月 - 1997年3月

      詳細を見る

  • 徳島大学   工学部   助教授

    1993年4月 - 1995年10月

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  • 新技術事業団   増原極微変換プロジェクト極微制御グループ   グループリーダー

    1991年4月 - 1993年3月

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  • 新技術事業団   増原極微変換プロジェクト極微制御グループ   研究員

    1988年12月 - 1991年3月

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  • 筑波大学   化学系   助手

    1986年 - 1988年

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  • 米国テキサス大学ダラス校   博士研究員

    1984年4月 - 1986年2月

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▼全件表示

所属学協会

委員歴

  • 光化学協会   顧問  

    2022年1月 - 2023年12月   

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    団体区分:学協会

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  • 国立陽明交通大学(台湾)   終身講座教授  

    2021年8月 - 現在   

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  • Research Center for Applied Sciences, Academia Sinica   Academic Advisory Committee  

    2020年1月 - 2025年12月   

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  • International Foundation of Photochemistry (IFP)   Executive member  

    2018年9月 - 現在   

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  • 国立交通大学(台湾)   講座教授  

    2015年8月 - 2021年7月   

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  • FWO (Research Foundation Flanders)   Expert Panel W&T3  

    2015年1月 - 2018年12月   

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    団体区分:学協会

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  • National Chiao Tung University (Taiwan)   Visiting Professor  

    2015年1月 - 2015年7月   

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    団体区分:学協会

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  • 国立交通大学(台湾)   客員教授  

    2015年1月 - 2015年7月   

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    団体区分:学協会

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  • 日本化学会   プログラム小委員会 部門幹事  

    2014年5月 - 2016年3月   

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    団体区分:学協会

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  • 日本化学会   ディビジョン運営委員会 ディビジョン主査  

    2014年5月 - 2016年2月   

      詳細を見る

    団体区分:学協会

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  • ACS Photonics   Editorial Advisory Board  

    2014年1月 - 2018年12月   

      詳細を見る

    団体区分:学協会

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  • 光化学協会   会長  

    2014年1月 - 2015年12月   

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    団体区分:学協会

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  • 石狩超電導直流送電プロジェクト推進協議会   構成員  

    2013年2月 - 2015年3月   

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    団体区分:自治体

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  • Nanotechnology Innovation Center for Environment & Ecosystem   Academic Committee  

    2012年7月 - 2017年12月   

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  • 独立行政法人日本学術振興会   学術システム研究センター研究員  

    2012年4月 - 2015年3月   

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    団体区分:学協会

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  • 文部科学省   「低炭素社会構築に向けた研究基盤ネットワーク整備」運営会議委員  

    2012年3月 - 2014年2月   

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    団体区分:政府

    2010.7.20-2011.3.31も同上

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  • 独立行政法人理化学研究所   客員主幹研究員  

    2012年1月 - 現在   

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    団体区分:学協会

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  • 第11回ナノテクノロジー総合シンポジウムプログラム委員  

    2012年 - 2013年3月   

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    団体区分:その他

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  • 日本学術会議   連携会員  

    2011年10月 - 2023年9月   

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    団体区分:学協会

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  • 第10回ナノテクノロジー総合シンポジウムプログラム委員  

    2011年10月 - 2012年3月   

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    団体区分:その他

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  • 独立行政法人日本学術振興会   特別研究員等審査会専門委員及び国際事業委員会書面審査員  

    2011年8月 - 2012年3月   

      詳細を見る

    団体区分:学協会

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  • 独立行政法人科学技術振興機構 戦略的創造研究推進事業   研究領域「元素戦略を基軸とする物質・材料の革新的機能の創出」領域アドバイザー  

    2011年5月 - 2018年3月   

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  • 独立行政法人新エネルギー・産業技術総合開発機構   NEDO技術委員  

    2011年5月 - 2013年3月   

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    団体区分:学協会

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  • 第9回ナノテクノロジー総合シンポジウム委員  

    2010年11月 - 2011年3月   

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    団体区分:学協会

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  • European Research Council   Peer Reviewer  

    2010年7月 - 2013年12月   

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    団体区分:学協会

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  • LPM2011国際顧問委員会   委員  

    2010年7月 - 2011年7月   

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    団体区分:学協会

    (A member of the International Advisory Committee of LPM 2011)

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  • 日本化学会   学術活性化委員会委員  

    2010年4月 - 2012年2月   

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    団体区分:学協会

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  • Journal of Photochemistry and Photobiology C, Photochemistry Review   Deputy Editor  

    2010年2月 - 2013年12月   

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    団体区分:その他

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  • Journal of Physical Chemistry   Advisory Board Member  

    2010年1月 - 2012年12月   

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    団体区分:学協会

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  • 光化学協会   理事  

    2010年1月 - 2011年12月   

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    団体区分:学協会

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  • 電子情報通信学会 超高速光エレクトニクス研究会   専門委員  

    2009年3月 - 2010年3月   

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    団体区分:学協会

    2007.3.12〜2007.12.31 同上

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  • ACS APPLIED MATERIALS&INTERFACES   EDITORIAL ADVISORY BOARD  

    2009年1月 - 2010年12月   

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    団体区分:学協会

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  • 独立行政法人日本学術振興会   科学研究費委員会専門委員  

    2008年12月 - 2010年11月   

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    団体区分:学協会

    2006.1.1〜2006.12.31 同上
    2002 同上

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  • 独立行政法人日本学術振興会   先端科学(FoS)シンポジウム事業委員会 専門委員  

    2008年8月 - 現在   

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    団体区分:学協会

    2005.3.1〜2006.6.28 同上

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  • 文部科学省   「元素戦略プロジェクト」審査委員会 外部専門家  

    2008年7月 - 2009年3月   

      詳細を見る

    団体区分:政府

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  • 独立行政法人科学技術振興機構 戦略的創造研究推進事業   研究領域「光の利用と物質材料・生命機能」領域アドバイザー  

    2008年5月 - 2015年3月   

      詳細を見る

    団体区分:学協会

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  • 日本化学会北海道支部   幹事  

    2008年3月 - 2010年2月   

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    団体区分:学協会

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  • 首都大学東京教員選考委員会   委員  

    2008年2月   

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    団体区分:その他

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  • 文部科学省   科学技術・学術審議会 専門委員  

    2007年12月 - 2010年1月   

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    団体区分:政府

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  • The 20th Korea Joint Forum 2008   Scientific Committee Member  

    2007年11月   

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    団体区分:学協会

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  • 文部科学省   ナノテクノロジー・ネットワーク運営委員会委員  

    2007年6月 - 2009年3月   

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    団体区分:政府

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  • TNANO (IEEE Transactions on Nanotechnology)   Associate Editor  

    2007年3月 - 2009年11月   

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    団体区分:学協会

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  • NEDOナノテクノロジーロードマップ「ナノインプリント・精密ビーム加工」   WG主査  

    2006年12月 - 2007年3月   

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    団体区分:学協会

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  • 文部科学省 科学技術政策研究所 科学技術動向研究センター   専門調査委員  

    2006年4月 - 2018年3月   

      詳細を見る

    団体区分:政府

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  • 独立行政法人日本学術振興会   先端科学(FoS)シンポジウム事業委員会 専門委員  

    2006年3月 - 2007年2月   

      詳細を見る

    団体区分:学協会

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  • 光化学協会   常任理事  

    2006年1月 - 2007年12月   

      詳細を見る

    団体区分:学協会

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  • 古河テクノリサーチ株式会社   NEDO平成17年度委託事業 有識者委員会 委員  

    2006年1月 - 2006年3月   

      詳細を見る

    団体区分:その他

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  • 財団法人光産業技術振興会   平成16年フェムト秒超加工技術フィージビリティ調査委員会 委員  

    2004年7月 - 2005年3月   

      詳細を見る

    団体区分:その他

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  • 独立行政法人日本学術振興会   第7回日米先端科学(JAFoS)シンポジウム2004 Planning Group Member 主査  

    2004年4月 - 2005年3月   

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    団体区分:その他

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  • 財団法人光技術振興協会   平成16年フェムト秒超加工研究会 幹事  

    2004年4月 - 2005年3月   

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    団体区分:その他

    2001年 同上

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  • 社団法人高温学会   レーザー加工学会査読委員会 査読委員  

    2004年4月 - 2005年3月   

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    団体区分:学協会

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  • LPM2004 国際会議 The 5th International Symposium on Laser Precision Microfabrication   Organizing Committee Member  

    2004年   

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    団体区分:その他

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  • 財団法人光産業技術振興協会   平成14年度光産業構造中長期展望専門委員会技術分科会委員  

    2002年   

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    団体区分:その他

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  • 社団法人日本セラミックス協会   「平成14年度セラミックスインテグレーション技術による新機能材料創製に関する研究」バッファーレイヤー調査研究委員会 委員  

    2002年   

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    団体区分:その他

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  • NEDO 新エネルギー産業技術総合開発機構   評価委員  

    2002年   

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    団体区分:その他

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  • 科学技術振興事業団   地域結集型共同研究事業中間評価専門委員  

    2002年   

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    団体区分:学協会

    科学技術振興事業団

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  • 財団法人光産業技術振興協会主催   「平成13年度光技術海外動向調査事業」動向調査団長  

    2002年   

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    団体区分:その他

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  • レーザー学会   第22回年次大会プログラム委員  

    2001年   

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    団体区分:学協会

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  • CLEO / PR 2001   プログラム委員会委員  

    2001年   

      詳細を見る

    団体区分:その他

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  • 2001 Photonic West (OSA)   LASEプログラム委員  

    2001年   

      詳細を見る

    団体区分:その他

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  • 社団法人電気学会   論文委員会 委員  

    2001年   

      詳細を見る

    団体区分:学協会

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  • 文部科学省 科学技術政策所   科学技術専門家ネットワーク専門調査員  

    2001年   

      詳細を見る

    団体区分:政府

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  • (社)電気学会   論文委員会委員  

    2001年   

      詳細を見る

    団体区分:学協会

    (社)電気学会

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  • 財団法人フォトンセンター   研究動向調査委員会 委員  

    2000年   

      詳細を見る

    団体区分:その他

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  • 第14回日本エム・イー学会   秋季大会プログラム委員  

    2000年   

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    団体区分:学協会

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  • 社団法人電子情報通信学会   レーザ・量子エレクトロニクス研究会専門委員  

    2000年   

      詳細を見る

    団体区分:学協会

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  • 財団法人光産業技術振興協会   技術動向調査委員会 委員  

    2000年   

      詳細を見る

    団体区分:学協会

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  • 財団法人四国産業・技術振興センター   医工融合領域フロンティア研究会委員  

    1999年   

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    団体区分:その他

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  • 財団法人マイクロマシンセンター   マイクロ流体システム調査委員会委員  

    1999年   

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    団体区分:その他

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  • 財団法人四国産業・技術振興センター   テクノサロン運営委員会メカトロニクス委員会 委員  

    1996年 - 1998年   

      詳細を見る

    団体区分:その他

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  • 日本機械学会   設計工学・システム部門運営委員,トピックス委員会委員  

    1995年   

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    団体区分:学協会

    日本機械学会

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  • 財団法人四国産業・技術振興センター   四国地域における新規産業創出支援機能に関する医療・福祉専門委員会 委員  

    1987年 - 1997年   

      詳細を見る

    団体区分:その他

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  • 日本化学会   トッピクス小委員会委員  

    1987年 - 1990年   

      詳細を見る

    団体区分:学協会

    日本化学会

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▼全件表示

 

論文

  • Improving Charge Transfer under Strong Coupling Conditions via Interfacial Modulation

    En Cao, Xu Shi, Tomoya Oshikiri, Yen-En Liu, Quan Sun, Keiji Sasaki, Hiroaki Misawa

    ACS Photonics   2024年2月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    DOI: 10.1021/acsphotonics.3c01733

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  • Distance-Dependent Energy Transfer under Modal Strong Coupling from CdSe/ZnS Quantum Dots to a Plasmonic Fabry–Pérot Cavity

    Takuya Okamoto, Azusa Onishi, Xu Shi, Tomoya Oshikiri, Kosei Ueno, Hiroaki Misawa, Vasudevanpillai Biju

    The Journal of Physical Chemistry C   128 ( 10 )   4208 - 4214   2024年2月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    DOI: 10.1021/acs.jpcc.3c08503

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  • Spatially Uniform and Quantitative Surface-Enhanced Raman Scattering under Modal Ultrastrong Coupling Beyond Nanostructure Homogeneity Limits

    Yoshiki Suganami, Tomoya Oshikiri, Hideyuki Mitomo, Keiji Sasaki, Yen En Liu, Xu Shi, Yasutaka Matsuo, Kuniharu Ijiro, Hiroaki Misawa

    ACS Nano   18 ( 6 )   4993 - 5002   2024年2月

     詳細を見る

    掲載種別:研究論文(学術雑誌)  

    We developed a substrate that enables highly sensitive and spatially uniform surface-enhanced Raman scattering (SERS). This substrate comprises densely packed gold nanoparticles (d-AuNPs)/titanium dioxide/Au film (d-ATA). The d-ATA substrate demonstrates modal ultrastrong coupling between localized surface plasmon resonances (LSPRs) of AuNPs and Fabry-Pérot nanocavities. d-ATA exhibits a significant enhancement of the near-field intensity, resulting in a 78-fold increase in the SERS signal for crystal violet (CV) compared to that of d-AuNP/TiO2 substrates. Importantly, high sensitivity and a spatially uniform signal intensity can be obtained without precise control of the shape and arrangement of the nanoscale AuNPs, enabling quantitative SERS measurements. Additionally, SERS measurements of rhodamine 6G (R6G) on this substrate under ultralow adsorption conditions (0.6 R6G molecules/AuNP) show a spatial variation in the signal intensity within 3%. These findings suggest that the SERS signal under modal ultrastrong coupling originates from multiple plasmonic particles with quantum coherence.

    DOI: 10.1021/acsnano.3c10959

    Scopus

    PubMed

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  • Unidirectional Optical Swarming of Gold Nanoparticles on Lithographically Fabricated Gold Nanopatterns

    Chih-Hao Huang, Ya-Chiao Lee, Tetsuhiro Kudo, Xu Shi, Kosei Ueno, Teruki Sugiyama, Hiroaki Misawa, Hiroshi Masuhara

    The Journal of Physical Chemistry C   2023年9月

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acs.jpcc.3c04949

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  • Investigation of Enhanced Water Oxidation under Plasmon–Nanocavity Strong Coupling Using In Situ Electrochemical Surface-Enhanced Raman Spectroscopy

    Xiaoqian Zang, Xu Shi, Yoshiki Suganami, Yen-En Liu, Tomoya Oshikiri, Hiroaki Misawa

    The Journal of Physical Chemistry C   127 ( 31 )   15087 - 15095   2023年7月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    DOI: 10.1021/acs.jpcc.3c03625

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  • Photoinduced interfacial electron transfer from perovskite quantum dots to molecular acceptors for solar cells. 国際誌

    Bhagyashree Mahesha Sachith, Zhijing Zhang, Palyam Subramanyam, Challapalli Subrahmanyam, Akihiro Furube, Naoto Tamai, Takuya Okamoto, Hiroaki Misawa, Vasudevanpillai Biju

    Nanoscale   15 ( 17 )   7695 - 7702   2023年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Bandgap-engineered inorganic and hybrid halide perovskite (HP) films, nanocrystals, and quantum dots (PQDs) are promising for solar cells. Fluctuations of photoinduced electron transfer (PET) rates affect the interfacial charge separation efficiencies of such solar cells. Electron donor- or acceptor-doped perovskite samples help analyze PET and harvest photogenerated charge carriers efficiently. Therefore, PET in perovskite-based donor-acceptor (D-A) systems has received considerable attention. We analyzed the fluctuations of interfacial PET from MAPbBr3 or CsPbBr3 PQDs to classical electron acceptors such as 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 1,2,4,5-tetracyanobenzene (TCNB) at single-particle and ensemble levels. The significantly negative Gibbs free energy changes of PET estimated from the donor-acceptor redox potentials, the donor-acceptor sizes, and the solvent dielectric properties help us clarify the PET in the above D-A systems. The dynamic nature of PET is apparent from the decrease in photoluminescence (PL) lifetimes and PL photocounts of PQDs with an increase in the acceptor concentrations. Also, the acceptor radical anion spectrum helps us characterize the charge-separated states. Furthermore, the PL blinking time and PET rate fluctuations (108 to 107 s-1) provide us with single-molecule level information about interfacial PET in perovskites.

    DOI: 10.1039/d3nr01032e

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  • Quantum-Coherence-Enhanced Hot-Electron Injection under Modal Strong Coupling

    Yen-En Liu, Xu Shi, Tomohiro Yokoyama, Soshun Inoue, Yuji Sunaba, Tomoya Oshikiri, Quan Sun, Mamoru Tamura, Hajime Ishihara, Keiji Sasaki, Hiroaki Misawa

    ACS Nano   17 ( 9 )   8315 - 8323   2023年4月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    DOI: 10.1021/acsnano.2c12670

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  • Halide Perovskite Single Crystals and Nanocrystal Films as Electron Donor-Acceptor Heterojunctions

    M. D. Shahjahan, Takuya Okamoto, Lata Chouhan, Bhagyashree Mahesha Sachith, Narayan Pradhan, Hiroaki Misawa, Vasudevanpillai Biju

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   2022年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    Halide perovskites are materials for future optical displays and solar cells. Electron donor-acceptor perovskite heterostructures with distinguishing halide compositions are promising for transporting and harvesting photogenerated charge carriers. Combined e-beam lithography and anion exchange are promising to develop such heterostructures but challenging to prepare multiple heterojunctions at desired locations in single crystals. We demonstrate swift laser trapping-assisted band gap engineering at the desired locations in MAPbBr(3) microrods, microplates, or nanocrystal thin films. The built-in donor-acceptor double and multi-heterojunction structures let us transport and trap photogenerated charge carriers from wide-band gap bromide to narrow-band gap iodide domains. We discuss the charge carrier transport and trapping mechanisms from the viewpoints of engineered bands and band continuity. This work offers a convenient method for designing single-, double- and multi-heterojunction donor-acceptor halide perovskites for photovoltaic, photonic, and electronic applications.

    DOI: 10.1002/anie.202215947

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  • Meta-lens light-sheet fluorescence microscopy for in vivo imaging 査読

    Yuan Luo, Ming Lun Tseng, Sunil Vyas, Ting-Yu Hsieh, Jui-Ching Wu, Shang-Yang Chen, Hsiao-Fang Peng, Vin-Cent Su, Tzu-Ting Huang, Hsin Yu Kuo, Cheng Hung Chu, Mu Ku Chen, Jia-Wern Chen, Yu-Chun Chen, Kuang-Yuh Huang, Chieh-Hsiung Kuan, Xu Shi, Hiroaki Misawa, Din Ping Tsai

    Nanophotonics   11 ( 9 )   1949 - 1959   2022年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1515/nanoph-2021-0748

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    その他リンク: https://www.degruyter.com/document/doi/10.1515/nanoph-2021-0748/pdf

  • Metasurface‐Based Abrupt Autofocusing Beam for Biomedical Applications 査読

    Yuan Luo, Ming Lun Tseng, Sunil Vyas, Hsin Yu Kuo, Cheng Hung Chu, Mu Ku Chen, Hsiang‐Chieh Lee, Wen‐Pin Chen, Vin‐Cent Su, Xu Shi, Hiroaki Misawa, Din Ping Tsai, Pan‐Chyr Yang

    Small Methods   6 ( 4 )   2101228 - 2101228   2022年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1002/smtd.202101228

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    その他リンク: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/smtd.202101228

  • Boosting Hydrogen Evolution at Visible Light Wavelengths Using a Photocathode with Modal Strong Coupling between Plasmons and a Fabry–Pérot Nanocavity 査読

    Tomoya Oshikiri, Haruki Jo, Xu Shi, Hiroaki Misawa

    Chemistry – A European Journal   28 ( 24 )   e202200288   2022年2月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Wiley  

    DOI: 10.1002/chem.202200288

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  • Improved water splitting efficiency of Au-NP-loaded Ga2O3 thin films in the visible region under strong coupling conditions

    Yaguang Wang, Xu Shi, Tomoya Oshikiri, Hiroaki Misawa

    Nanoscale Advances   2022年

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Royal Society of Chemistry (RSC)  

    We fabricate a novel photoanode consisting of TiO2/Au nanoparticles (Au-NPs)/Ga2O3/TiN/Au film (TAGA), efficiently increasing light absorption and electron transfer from Au-NPs to Ga2O3 under modal strong coupling. A TiN thin...

    DOI: 10.1039/d2na00768a

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  • A Fabry-Pérot cavity coupled surface plasmon photodiode for electrical biomolecular sensing 査読

    Giles Allison, Amrita Kumar Sana, Yuta Ogawa, Hidemi Kato, Kosei Ueno, Hiroaki Misawa, Koki Hayashi, Hironori Suzuki

    Nature Communications   2021年12月

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1038/s41467-021-26652-7

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  • Near-Field Imaging and Time-Domain Dynamics of Photonic Topological Edge States in Plasmonic Nanochains 査読

    Qiuchen Yan, En Cao, Quan Sun, Yutian Ao, Xiaoyong Hu, Xu Shi, Qihuang Gong, Hiroaki Misawa

    Nano Letters   21 ( 21 )   9270 - 9278   2021年11月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acs.nanolett.1c03324

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  • Emerging Materials for Plasmon-assisted Photoelectrochemical Water Splitting 査読

    Palyam Subramanyam, Bhagatram Meena, Vasudevanpillai Biju, Hiroaki Misawa, Subrahmanyam Challapalli

    Journal of Photochemistry and Photobiology C: Photochemistry Reviews   51   100472 - 100472   2021年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.jphotochemrev.2021.100472

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  • Extrinsic Chirality by Interference between Two Plasmonic Modes on an Achiral Rectangular Nanostructure 査読

    Tomoya Oshikiri, Quan Sun, Hiroki Yamada, Shuai Zu, Keiji Sasaki, Hiroaki Misawa

    ACS Nano   15 ( 10 )   16802 - 16810   2021年9月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acsnano.1c07137

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  • Highly Sensitive and Spatially Homogeneous Surface-Enhanced Raman Scattering Substrate under Plasmon–Nanocavity Coupling 招待 査読

    Xiaoqian Zang, Xu Shi, Tomoya Oshikiri, Kosei Ueno, Yuji Sunaba, Keiji Sasaki, Hiroaki Misawa

    The Journal of Physical Chemistry C   125 ( 36 )   19880 - 19886   2021年9月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acs.jpcc.1c05788

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  • Water Oxidation under Modal Ultrastrong Coupling Conditions Using Gold/Silver Alloy Nanoparticles and Fabry–Pérot Nanocavities 査読

    Yoshiki Suganami, Tomoya Oshikiri, Xu Shi, Hiroaki Misawa

    Angewandte Chemie International Edition   60 ( 34 )   18438 - 18442   2021年7月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1002/anie.202103445

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    その他リンク: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/anie.202103445

  • Cubic-Phase Metasurface for Three-Dimensional Optical Manipulation 査読

    Hsin Yu Kuo, Sunil Vyas, Cheng Hung Chu, Mu Ku Chen, Xu Shi, Hiroaki Misawa, Yu-Jung Lu, Yuan Luo, Din Ping Tsai

    Nanomaterials   11 ( 7 )   1730 - 1730   2021年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.3390/nano11071730

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  • Varifocal Metalens for Optical Sectioning Fluorescence Microscopy 査読

    Yuan Luo, Cheng Hung Chu, Sunil Vyas, Hsin Yu Kuo, Yu Hsin Chia, Mu Ku Chen, Xu Shi, Takuo Tanaka, Hiroaki Misawa, Yi-You Huang, Din Ping Tsai

    Nano Letters   21 ( 12 )   5133 - 5142   2021年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acs.nanolett.1c01114

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  • Revealing the Chiroptical Response of Plasmonic Nanostructures at the Nanofemto Scale 査読

    Shuai Zu, Quan Sun, En Cao, Tomoya Oshikiri, Hiroaki Misawa

    Nano Letters   21 ( 11 )   4780 - 4786   2021年6月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acs.nanolett.1c01322

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  • Near-Perfect Absorption of Light by Coherent Plasmon–Exciton States 査読

    Daniel E. Gómez, Xu Shi, Tomoya Oshikiri, Ann Roberts, Hiroaki Misawa

    Nano Letters   21 ( 9 )   3864 - 3870   2021年5月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acs.nanolett.1c00389

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  • Hot-carrier Separation Induced by the Electric Field of a p-n Junction between Titanium Dioxide and Nickel Oxide 査読 国際誌

    Keisuke Nakamura, Tomoya Oshikiri, Kosei Ueno, Hiromichi Ohta, Hiroaki Misawa

    Chemistry Letters   50 ( 2 )   374 - 377   2021年2月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:The Chemical Society of Japan  

    DOI: 10.1246/cl.200790

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  • Near-field engineering for boosting the photoelectrochemical activity to a modal strong coupling structure 査読 国際誌

    Yanfeng Cao, Xu Shi, Tomoya Oshikiri, Shuai Zu, Yuji Sunaba, Keiji Sasaki, Hiroaki Misawa

    Chemical Communications   57 ( 4 )   524 - 527   2021年1月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Royal Society of Chemistry (RSC)  

    <p>The near field was tailored to be enhanced at the three-phase boundary of Au-NPs/TiO2/H2O for efficient water oxidation.</p>

    DOI: 10.1039/d0cc07335k

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  • A photoanode with plasmonic nanoparticles of earth abundant bismuth for photoelectrochemical reactions 査読 国際共著 国際誌

    Palyam Subramanyam, Melepurath Deepa, Sai Santosh Kumar Raavi, Hiroaki Misawa, Vasudevanpillai Biju, Challapalli Subrahmanyam

    Nanoscale Advances   2 ( 12 )   5591 - 5599   2020年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Royal Society of Chemistry (RSC)  

    <p>A wide range of technologies has been developed for producing hydrogen economically and in greener ways.</p>

    DOI: 10.1039/d0na00641f

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  • Plasmon-induced electron injection into the large negative potential conduction band of Ga2O3 for coupling with water oxidation 査読 国際誌

    Yaguang Wang, Xu Shi, Tomoya Oshikiri, Shuai Zu, Kosei Ueno, Hiroaki Misawa

    Nanoscale   12 ( 44 )   22674 - 22679   2020年11月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Royal Society of Chemistry (RSC)  

    <p>The plasmonic Ga2O3 photoanode with the interfacial TiO2 modification provide both a high reduction ability and an oxidation ability.</p>

    DOI: 10.1039/d0nr06319c

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  • Enhanced photocurrent generation from indium–tin-oxide/Fe2TiO5 hybrid nanocone arrays 査読 国際共著 国際誌

    Kai Chen, Thang Duy Dao, Thien Duc Ngo, Hai Dang Ngo, Akemi Tamanai, Satoshi Ishii, Xiangping Li, Hiroaki Misawa, Tadaaki Nagao

    Nano Energy   76   104965 - 104965   2020年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

    DOI: 10.1016/j.nanoen.2020.104965

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  • Ultrafast photoemission electron microscopy: Capability and potential in probing plasmonic nanostructures from multiple domains 査読 国際誌

    Quan Sun, Shuai Zu, Hiroaki Misawa

    The Journal of Chemical Physics   153 ( 12 )   120902 - 120902   2020年9月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AIP Publishing  

    The near-field properties and dynamics of plasmonic nanostructures play a crucial role in several fundamental concepts in physics and chemistry, and they are widely relevant in plasmonic applications. Ultrafast photoemission electron microscopy (PEEM) is a novel approach that has been widely applied to probe plasmonic nanostructures from multiple domains. Furthermore, PEEM is the only technique that provides nanometer spatial resolution, sub-femtosecond temporal resolution, and tens to hundreds of millielectron volt energy resolution. This allows for extremely sensitive observations of plasmonic field oscillations, field dephasing, and hot electrons. This Perspective provides a brief overview of the basic principles and main applications of ultrafast PEEM. The research progress of ultrafast PEEM in plasmonics is highlighted from three points of view: near-field imaging, near-field spectroscopy, and ultrafast dynamics. Future applications of PEEM in plasmonics for the probing of plasmonic hot electron dynamics in the energy and time domains are proposed and discussed.

    DOI: 10.1063/5.0013659

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  • Interfacial Structure-Modulated Plasmon-Induced Water Oxidation on Strontium Titanate 査読 国際誌

    Xu Shi, Xiaowei Li, Takahiro Toda, Tomoya Oshikiri, Kosei Ueno, Kentaro Suzuki, Kei Murakoshi, Hiroaki Misawa

    ACS Applied Energy Materials   3 ( 6 )   5675 - 5683   2020年6月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    Plasmon-induced carrier transfer at metallic nanoparticle/semiconductor heterojunctions has received great attention because of its tremendous potential in applications, such as photocatalysis and photoelectric and energy conversion. The interfacial structure of the heterojunction is known to play an important role in charge transfer as well as the subsequent chemical reactions. Here, we studied the Au nanoparticle (Au-NP)-loaded (100)-, (110)-, and (111)-oriented single-crystalline strontium titanate (STO) as a model to investigate the effects of interfacial structure on the plasmon-induced charge separation between the metallic nanoparticles and semiconductors. Via photoelectrochemical characterizations, we found that the efficiency of the plasmon-induced water oxidation reaction on STO(100) is more than 1.4 times higher than that on the other two orientation facets. This enhancement was demonstrated to stem from the high oxidation ability of plasmon-induced holes captured in the surface states. Furthermore, the molecular processes of water oxidation were investigated by monitoring the surface oxidation status of Au-NP/STO as intermediates of plasmon-induced water oxidation using in situ electrochemical surface-enhanced Raman spectroscopy. The onset potential of Au-O vibrations on Au-NP/STO(100) was determined to be 0.4 V more negative than that of Au-NP/STO(110), further confirming the higher oxidation ability of the plasmon-induced holes. Our observation provides an opportunity to efficiently modulate plasmon-excited hot-carrier reaction processes for photochemical applications through interfacial engineering.

    DOI: 10.1021/acsaem.0c00648

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  • Site-Selective Deposition of a Cobalt Cocatalyst onto a Plasmonic Au/TiO2 Photoanode for Improved Water Oxidation 査読 国際誌

    Megumi Okazaki, Yoshiki Suganami, Naoki Hirayama, Hiroko Nakata, Tomoya Oshikiri, Toshiyuki Yokoi, Hiroaki Misawa, Kazuhiko Maeda

    ACS Applied Energy Materials   3 ( 6 )   5142 - 5146   2020年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    Plasmonic Au/TiO2 thin film works as a stable water oxidation photoanode. Here we show that site-selective deposition of nanosized CoOx as a water oxidation cocatalyst at the edge of Au nanoparticles on the TiO2 film improves the photoelectrochemical water oxidation activity. The nanosized CoOx was deposited by a photoassisted electrochemical method onto the Au/TiO2 thin film. The CoOx loading amount was controllable by changing the amount of electric charge that flowed during the deposition, which influenced the photoelectrochemical performance. Under visible light, the optimized CoOx/Au/TiO2 thin film generated stable photoanodic current, which was similar to 3 times higher than that obtained using Au/TiO2.

    DOI: 10.1021/acsaem.0c00857

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  • Ultrafast Electron Cooling and Decay in Monolayer WS2 Revealed by Time- and Energy-Resolved Photoemission Electron Microscopy 査読 国際共著 国際誌

    Yaolong Li, Wei Liu, Yunkun Wang, Zhaohang Xue, Yu-Chen Leng, Aiqin Hu, Hong Yang, Ping-Heng Tan, Yunquan Liu, Hiroaki Misawa, Quan Sun, Yunan Gao, Xiaoyong Hu, Qihuang Gong

    Nano Letters   20 ( 5 )   3747 - 3753   2020年5月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    DOI: 10.1021/acs.nanolett.0c00742

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  • Enhancement of Selective Fixation of Dinitrogen to Ammonia under Modal Strong Coupling Conditions 査読 国際誌

    Tomoya Oshikiri, Xu Shi, Hiroaki Misawa

    European Journal of Inorganic Chemistry   2020 ( 15-16 )   1396 - 1401   2020年4月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Wiley  

    DOI: 10.1002/ejic.201901260

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    その他リンク: http://onlinelibrary.wiley.com/wol1/doi/10.1002/ejic.201901260/fullpdf

  • Front Cover: Enhancement of Selective Fixation of Dinitrogen to Ammonia Under Modal Strong Coupling Conditions (Eur. J. Inorg. Chem. 15‐16/2020)

    Tomoya Oshikiri, Xu Shi, Hiroaki Misawa

    European Journal of Inorganic Chemistry   2020 ( 15-16 )   1345 - 1345   2020年4月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Wiley  

    DOI: 10.1002/ejic.202000339

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  • Correlation between Near-Field Enhancement and Dephasing Time in Plasmonic Dimers 査読 国際共著 国際誌

    Yaolong Li, Quan Sun, Shuai Zu, Xu Shi, Yunquan Liu, Xiaoyong Hu, Kosei Ueno, Qihuang Gong, Hiroaki Misawa

    Physical Review Letters   124 ( 16 )   163901 - 163901   2020年4月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Physical Society (APS)  

    Near-field enhancement and dephasing time play critical roles in several applications of localized surface plasmon resonance. Here, using an example gold dimer system, we reveal the correlation between the near-field enhancement and dephasing time via time-resolved photoemission electron microscopy. Compared with isolated particles, dimers with small gap sizes show stronger near-field enhancement and shorter dephasing times. These results are well reproduced by numerical simulations and further explained by a coupled dipole approximation model. The roles of near- and far-field coupling and plasmon localization in balancing near-field enhancement and dephasing time are also unveiled.

    DOI: 10.1103/physrevlett.124.163901

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    その他リンク: http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevLett.124.163901/fulltext

  • Chiral Second-Harmonic Generation from Monolayer WS2/Aluminum Plasmonic Vortex Metalens 査読 国際共著 国際誌

    Wan-Ping Guo, Wei-Yun Liang, Chang-Wei Cheng, Wei-Lin Wu, Yen-Ting Wang, Quan Sun, Shuai Zu, Hiroaki Misawa, Pi-Ju Cheng, Shu-Wei Chang, Hyeyoung Ahn, Minn-Tsong Lin, Shangjr Gwo

    Nano Letters   20 ( 4 )   2857 - 2864   2020年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    Two-dimensional spiral plasmonic structures have emerged as a versatile approach to generate near-field vortex fields with tunable topological charges. We demonstrate here a far-field approach to observe the chiral second-harmonic generation (SHG) at designated visible wavelengths from a single plasmonic vortex metalens. This metalens comprises an Archimedean spiral slit fabricated on atomically flat aluminum epitaxial film, which allows for precise tuning of plasmonic resonances and subsequent transfer of two-dimensional materials on top of the spiral slit. The nonlinear optical measurements show a giant SHG circular dichroism. Furthermore, we have achieved an enhanced chiral SHG conversion efficiency (about an order of magnitude greater than the bare aluminum lens) from monolayer tungsten disulfide (WS2)/aluminum metalens, which is designed at the C-exciton resonance of WS2. Since the C-exciton is not a valley exciton, the enhanced chiral SHG in this hybrid system originates from the plasmonic vortex field-enhanced SHG under the optical spin-orbit interaction.

    DOI: 10.1021/acs.nanolett.0c00645

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  • On-chip MIC by Combining Concentration Gradient Generator and Flanged Chamber Arrays 査読 国際共著 国際誌

    Xiao-Yan Zhang, Zhe-Yu Li, Kose Ueno, Hiroaki Misawa, Nan-Qi Ren, Kai Sun

    Micromachines   11 ( 2 )   207 - 207   2020年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:MDPI AG  

    Minimum inhibition concentration (MIC) of antibiotic is an effective value to ascertain the agent and minimum dosage of inhibiting bacterial growth. However, current techniques to determine MIC are labor intensive and time-consuming, and require skilled operator and high initial concentration of bacteria. To simplify the operation and reduce the time of inhibition test, we developed a microfluidic system, containing a concentration generator and sub-micro-liter chambers, for rapid bacterial growth and inhibition test. To improve the mixing effect, a micropillar array in honeycomb-structure channels is designed, so the steady concentration gradient of amoxicillin can be generated. The flanged chambers are used to culture bacteria under the condition of continuous flow and the medium of chambers is refreshed constantly, which could supply the sufficient nutrient for bacteria growth and take away the metabolite. Based on the microfluidic platform, the bacterial growth with antibiotic inhibition on chip can be quantitatively measured and MIC can be obtained within six hours using low initial concentration of bacteria. Overall, this microfluidic platform has the potential to provide rapidness and effectiveness to screen bacteria and determine MIC of corresponding antibiotics in clinical therapies.

    DOI: 10.3390/mi11020207

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  • Role of Depolarization Factors in the Evolution of a Dipolar Plasmonic Spectral Line in the Far- and Near-Field Regimes 査読 国際共著 国際誌

    Mochamad Januar, Bei Liu, Jui-Ching Cheng, Koji Hatanaka, Hiroaki Misawa, Hui-Hsin Hsiao, Kou-Chen Liu

    The Journal of Physical Chemistry C   124 ( 5 )   3250 - 3259   2020年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    DOI: 10.1021/acs.jpcc.9b10485

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  • Arbitrary control of the diffusion potential between a plasmonic metal and a semiconductor by an angstrom-thick interface dipole layer 査読 国際誌

    Tomoya Oshikiri, Hiroki Sawayanagi, Keisuke Nakamura, Kosei Ueno, Takayoshi Katase, Hiromichi Ohta, Hiroaki Misawa

    The Journal of Chemical Physics   152 ( 3 )   034705 - 034705   2020年1月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AIP Publishing  

    DOI: 10.1063/1.5134900

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  • Engineering Ultrafast Carrier Dynamics at the Graphene/GaAs Interface by Bulk Doping Level 査読 国際共著 国際誌

    Jinghuan Yang, Quan Sun, Wei Liu, Zhibin Zhang, Xiaoyong Hu, Kaihui Liu, Hong Yang, Hiroaki Misawa, Qihuang Gong

    Advanced Optical Materials   7 ( 19 )   1900580 - 1900580   2019年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Wiley  

    DOI: 10.1002/adom.201900580

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    その他リンク: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/adom.201900580

  • Injection compression molding of transmission-type Fano resonance biochips for multiplex sensing applications 査読 国際共著 国際誌

    Kuang-Li Lee, Meng-Lin You, Xu Shi, Yi-Ru Li, Kosei Ueno, Hiroaki Misawa, Pei-Kuen Wei

    Applied Materials Today   16   72 - 82   2019年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

    DOI: 10.1016/j.apmt.2019.05.003

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  • Efficient Hot‐Electron Transfer under Modal Strong Coupling Conditions with Sacrificial Electron Donors 査読

    Yanfeng Cao, Tomoya Oshikiri, Xu Shi, Kosei Ueno, Jie Li, Hiroaki Misawa

    ChemNanoMat   5 ( 8 )   972 - 972   2019年8月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Wiley  

    DOI: 10.1002/cnma.201900273

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  • Efficient Hot‐Electron Transfer under Modal Strong Coupling Conditions with Sacrificial Electron Donors 査読 国際誌

    Yanfeng Cao, Tomoya Oshikiri, Xu Shi, Kosei Ueno, Jie Li, Hiroaki Misawa

    ChemNanoMat   5 ( 8 )   1008 - 1014   2019年8月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Wiley  

    DOI: 10.1002/cnma.201900178

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    その他リンク: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/cnma.201900178

  • Ammonia photosynthesis via an association pathway using a plasmonic photoanode and a zirconium cathode 査読 国際誌

    Tomoya Oshikiri, Kosei Ueno, Hiroaki Misawa

    Green Chemistry   21 ( 16 )   4443 - 4448   2019年7月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Royal Society of Chemistry (RSC)  

    <p>Ammonia photosynthesis under visible light irradiation <italic>via</italic> an associative pathway using a plasmonic photoanode and a zirconium cathode is proposed.</p>

    DOI: 10.1039/c9gc01658a

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  • Applications of ultrafast photoemission electron microscopy in nanophotonics 招待 査読

    Chin. J. Lasers   46 ( 5 )   0508008 - 0508001   2019年5月

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    記述言語:中国語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.3788/cjl201946.0508001

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  • Twisted Surface Plasmons with Spin‐Controlled Gold Surfaces 査読 国際共著 国際誌

    Wei‐Yi Tsai, Quan Sun, Guangwei Hu, Pin Chieh Wu, Ren Jie Lin, Cheng‐Wei Qiu, Kosei Ueno, Hiroaki Misawa, Din Ping Tsai

    Advanced Optical Materials   7 ( 8 )   1801060 - 1801060   2019年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Wiley  

    DOI: 10.1002/adom.201801060

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    その他リンク: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/adom.201801060

  • Formation of Nanostructure-controlled Strong Coupling of Porphyrin Molecules and Silver Nanoparticles Using Layered Silicates 査読 国際誌

    Miharu Eguchi, Jie Li, Kosei Ueno, Hiroaki Misawa

    Chemistry Letters   48 ( 3 )   211 - 214   2019年3月

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    担当区分:最終著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:The Chemical Society of Japan  

    The nanostructure control of strong coupling has been less thoroughly investigated in organic semiconductor structures than in resonator structures. We achieved strong coupling by introducing a layered silicate between a silver nanodisk resonator and a porphyrin organic semiconductor, where the porphyrin nanostructure is monomeric and parallel to the silicate surface.

    DOI: 10.1246/cl.180925

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  • Control of plasmon dephasing time using stacked nanogap gold structures for strong near-field enhancement 査読 国際共著 国際誌

    Kosei Ueno, Jinghuan Yang, Quan Sun, Daisuke Aoyo, Han Yu, Tomoya Oshikiri, Atsushi Kubo, Yasutaka Matsuo, Qihuang Gong, Hiroaki Misawa

    Applied Materials Today   14   159 - 165   2019年3月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

    The construction of metallic nanostructures with strong near-field enhancement is becoming increasingly significant for the practical use of plasmonic devices, such as plasmonic sensors and light-energy conversion systems. Importantly, the near-field enhancement effect depends on the plasmon dephasing time. Here, we propose a method for controlling plasmon dephasing time by utilizing plasmonic coupling for stronger near-field enhancement. Ordered arrays of stacked nanogap gold (Au) structures composed of a metal/insulator/metal nanostructure were fabricated by electron beam lithography and dry etching processes on a niobium-doped titanium dioxide substrate. The dark plasmon mode was excited by the near-field coupling between the upper and lower Au nanostructures separated by an alumina layer with a thickness of 15 nm. A strong near-field enhancement effect was induced by the localization of the electromagnetic field between the upper and lower Au nanostructures and the longer plasmon dephasing time based on the excitation of the dark plasmon mode. It is noteworthy that the dephasing time of the dark plasmon mode measured by time-resolved photoemission electron microscopy was extended 3-fold compared with that of the plasmon mode of the Au nanoblock, which can be controlled by the structural design of the stacked nanogap Au structures. (C) 2018 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.apmt.2018.12.004

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  • Revealing the plasmon coupling in gold nanochains directly from the near field 査読 国際誌

    Quan Sun, Han Yu, Kosei Ueno, Shuai Zu, Yasutaka Matsuo, Hiroaki Misawa

    Opto-Electronic Advances   2 ( 4 )   18003001 - 18003007   2019年3月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Opto-Electronic Advances  

    DOI: 10.29026/oea.2019.180030

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  • Second Harmonic Light Manipulation with Vertical Split Ring Resonators 査読 国際共著 国際誌

    Wei‐Yi Tsai, Tsung Lin Chung, Hui‐Hsin Hsiao, Jia‐Wern Chen, Ren Jie Lin, Pin Chieh Wu, Greg Sun, Chih‐Ming Wang, Hiroaki Misawa, Din Ping Tsai

    Advanced Materials   31 ( 7 )   1806479 - 1806479   2019年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Wiley  

    DOI: 10.1002/adma.201806479

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  • Exotic Mode Suppression in Plasmonic Heterotrimer System 査読 国際共著 国際誌

    Hanfa Song, Quan Sun, Jie Li, Fan Yang, Jinghuan Yang, Yaolong Li, Kosei Ueno, Qihuang Gong, Hiroaki Misawa

    The Journal of Physical Chemistry C   123 ( 2 )   1398 - 1405   2019年1月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    DOI: 10.1021/acs.jpcc.8b10263

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  • Bacterial Concentration Detection using a PCB-based Contactless Conductivity Sensor 査読 国際共著 国際誌

    Xiao-Yan Zhang, Zhe-Yu Li, Yu Zhang, Xiao-Qian Zang, Kosei Ueno, Hiroaki Misawa, Kai Sun

    Micromachines   10 ( 1 )   55 - 55   2019年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:MDPI AG  

    Capacitively coupled contactless conductivity detection (C4D) is an improved approach to avoid the problems of labor-intensive, time-consuming and insufficient accuracy of plate count as well as the high-cost apparatus of flow cytometry (FCM) in bacterial counting. This article describes a novel electrode-integrated printed-circuit-board (PCB)-based C4D device, which supports the simple and safe exchange of capillaries and improves the sensitivity and repeatability of the contactless detection. Furthermore, no syringe pump is needed in the detection, it reduces the system size, and, more importantly, avoids the effect on the bacteria due to high pressure. The recovered bacteria after C4D detection at excitation of 25 Vpp and 60–120 kHz were analyzed by flow cytometry, and a survival rate higher than 96% was given. It was verified that C4D detection did not influence the bacterial viability. Moreover, bacteria concentrations from 106 cells/mL to 108 cells/mL were measured in a linear range, and relative standard deviation (RSD) is below 0.2%. In addition, the effects on bacteria and C4D from background solutions were discussed. In contrast to common methods used in most laboratories, this method may provide a simple solution to in situ detection of bacterial cultures.

    DOI: 10.3390/mi10010055

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  • Insight of modal strong coupling and its application to photochemical reactions (Conference Presentation) 査読

    Hiroaki Misawa, Xu Shi, Kosei Ueno, Tomoya Oshikiri, Quan Sun, Keiji Sasaki

    Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XVII   2019年

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1117/12.2527653

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  • Ultrabroad and Angle Tunable THz Filter Based on Multiplexed Metallic Bar Resonators 査読 国際共著 国際誌

    Weiwei Liu, Zijie Dai, Jing Yang, Quan Sun, Cheng Gong, Nan Zhang, Kosei Ueno, Hiroaki Misawa

    IEEE Photonics Technology Letters   30 ( 24 )   2103 - 2106   2018年12月

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    担当区分:最終著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Institute of Electrical and Electronics Engineers ({IEEE})  

    DOI: 10.1109/LPT.2018.2877964

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  • Manipulation of the dephasing time by strong coupling between localized and propagating surface plasmon modes 査読 国際共著 国際誌

    Jinghuan Yang, Quan Sun, Kosei Ueno, Xu Shi, Tomoya Oshikiri, Hiroaki Misawa, Qihuang Gong

    Nature Communications   9 ( 1 )   4858   2018年12月

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

    DOI: 10.1038/s41467-018-07356-x

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    その他リンク: http://www.nature.com/articles/s41467-018-07356-x

  • Enhanced water splitting under modal strong coupling conditions 査読 国際誌

    Xu Shi, Kosei Ueno, Tomoya Oshikiri, Quan Sun, Keiji Sasaki, Hiroaki Misawa

    Nature Nanotechnology   13 ( 10 )   953 - 958   2018年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

    DOI: 10.1038/s41565-018-0208-x

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    その他リンク: http://www.nature.com/articles/s41565-018-0208-x.pdf

  • Optical Characterization of Gold Nanoblock Dimers: From Capacitive Coupling to Charge Transfer Plasmons and Rod Modes 査読 国際共著 国際誌

    Man-Nung Su, Quan Sun, Kosei Ueno, Wei-Shun Chang, Hiroaki Misawa, Stephan Link

    The Journal of Physical Chemistry C   122 ( 31 )   18005 - 18011   2018年8月

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society ({ACS})  

    DOI: 10.1021/acs.jpcc.8b05755

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  • Plasmon-Assisted Polarity Switching of a Photoelectric Conversion Device by UV and Visible Light Irradiation 査読 国際誌

    Keisuke Nakamura, Tomoya Oshikiri, Kosei Ueno, Takayoshi Katase, Hiromichi Ohta, Hiroaki Misawa

    The Journal of Physical Chemistry C   122 ( 25 )   14064 - 14071   2018年6月

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    担当区分:最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    DOI: 10.1021/acs.jpcc.8b01198

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  • Solid-State Plasmonic Solar Cells 査読

    Kosei Ueno, Tomoya Oshikiri, Quan Sun, Xu Shi, Hiroaki Misawa

    Chemical Reviews   118 ( 6 )   2955 - 2993   2018年3月

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    記述言語:英語   出版者・発行元:American Chemical Society  

    Metallic nanoparticles such as silver and gold show localized surface plasmon resonances (LSPRs), which are associated with near-field enhancement effects in the vicinity of nanoparticles. Therefore, strong light-matter interaction is induced by the near-field enhancement effects of LSPRs. Because the resonant wavelength of LSPRs can be easily controlled by the size and shape of the metallic nanoparticles in the visible and near-infrared wavelength range, LSPRs have received considerable attention as optical antennae for light energy conversion systems such as solar cells. LSPRs decay very quickly as a result of light scattering and excitation of electron-hole pairs in the metal itself. However, in addition to the near-field enhancement effect, this light scattering and electron-hole pair excitation, which are known to cause loss of LSPRs, can be utilized as a solar cell enhancement mechanism. Here, we focus on plasmonic solid-state solar cells. The mechanisms of the light scattering by LSPRs, near-field enhancement, and plasmon-induced charge separation based on electron-hole pair excitations can be clarified. We review the related studies from the viewpoint of these mechanisms rather than material science.

    DOI: 10.1021/acs.chemrev.7b00235

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  • Ultrafast Plasmons Probed by Photoemission Electron Microscopy 査読

    Quan Sun, Kosei Ueno, Hiroaki Misawa

    The 9th International Symposium on Ultrafast Phenomena and Terahertz Waves   2018年

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    出版者・発行元:OSA  

    DOI: 10.1364/isuptw.2018.tud3

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  • Exploring the Near-Field of Strongly Coupled Waveguide-Plasmon Modes by Plasmon-Induced Photocurrent Generation Using a Gold Nanograting-Loaded Titanium Dioxide Photoelectrode 査読

    Jingchun Guo, Kosei Ueno, Jinghuan Yang, Xu Shi, Jie Li, Quan Sun, Tomoya Oshikiri, Hiroaki Misawa

    JOURNAL OF PHYSICAL CHEMISTRY C   121 ( 39 )   21627 - 21633   2017年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Near-field spectrum measurement techniques, including near-field scanning optical microscopy, electron energy loss spectroscopy, and multiphoton photoemission electron microscopy, are powerful means to investigate near-field interactions directly on closely spaced metallic nanoparticles or a metallic nanostructure coupled with optical modes, such as whispering gallery mode and waveguide mode, which are called coupled plasmonic systems. In the present study, we have successfully measured the near-field spectra of coupled plasmonic systems using a simple photoelectrochemical measurement based on plasmon-induced water oxidation. Coupling was explored between the localized surface plasmon resonance (LSPR.) mode and waveguide mode of periodic gold nanogratings patterned on a thin titanium dioxide waveguide film. It is known that the far-field reflection spectrum of this waveguide-LSPR coupling system shows a complicated shape with multiple peaks, and the coupling has been explored by numerical electromagnetic simulations so far. However, in this study, it was clearly elucidated that an internal quantum efficiency (IQE) spectrum observed in the plasmon-induced photocurrent generation has successfully reproduced the near-field spectrum predicted by electromagnetic simulations under the coupling conditions. The photocurrent generation based on the plasmon-induced charge separation is due to the near-field effect, and it can be considered that the IQE spectrum corresponds to the near-field spectrum. This study paves a new way to indirectly measure the near-field spectrum of plasmonic systems.

    DOI: 10.1021/acs.jpcc.7b07707

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  • Interplay of hot electrons from localized and propagating plasmons 査読

    Chung V. Hoang, Koki Hayashi, Yasuo Ito, Naoki Gorai, Giles Allison, Xu Shi, Quan Sun, Zhenzhou Cheng, Kosei Ueno, Keisuke Goda, Hiroaki Misawa

    NATURE COMMUNICATIONS   8 ( 1 )   2017年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:NATURE PUBLISHING GROUP  

    Plasmon-induced hot-electron generation has recently received considerable interest and has been studied to develop novel applications in optoelectronics, photovoltaics and green chemistry. Such hot electrons are typically generated from either localized plasmons in metal nanoparticles or propagating plasmons in patterned metal nanostructures. Here we simultaneously generate these heterogeneous plasmon-induced hot electrons and exploit their cooperative interplay in a single metal-semiconductor device to demonstrate, as an example, wavelength-controlled polarity-switchable photoconductivity. Specifically, the dual-plasmon device produces a net photocurrent whose polarity is determined by the balance in population and directionality between the hot electrons from localized and propagating plasmons. The current responsivity and polarity-switching wavelength of the device can be varied over the entire visible spectrum by tailoring the hot-electron interplay in various ways. This phenomenon may provide flexibility to manipulate the electrical output from light-matter interaction and offer opportunities for biosensors, long-distance communications, and photoconversion applications.

    DOI: 10.1038/s41467-017-00815-x

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  • Spatial evolution of the near-field distribution on planar gold nanoparticles with the excitation wavelength across dipole and quadrupole modes 査読

    Jinghuan Yang, Quan Sun, Han Yu, Kosei Ueno, Hiroaki Misawa, Qihuang Gong

    PHOTONICS RESEARCH   5 ( 3 )   187 - 193   2017年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    We investigate the superposition properties of the dipole and quadrupole plasmon modes in the near field both experimentally, by using photoemission electron microscopy (PEEM), and theoretically. In particular, the asymmetric near-field distributions on gold (Au) nanodisks and nanoblocks under oblique incidence with different polarizations are investigated in detail. The results of PEEM measurements show that the evolutions of the asymmetric near-field distributions are different between the excitation with s-polarized and p-polarized light. The experimental results can be reproduced very well by numerical simulations and interpreted as the superposition of the dipole and quadrupole modes with the help of analytic calculations. Moreover, we hypothesize that the electrons collected by PEEM are mainly from the plasmonic hot spots located at the plane in the interface between the Au particles and the substrate in the PEEM experiments. (C) 2017 Chinese Laser Press

    DOI: 10.1364/PRJ.5.000187

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  • Water splitting using a three-dimensional plasmonic photoanode with titanium dioxide nano-tunnels 査読

    Ryohei Takakura, Tomoya Oshikiri, Kosei Ueno, Xu Shi, Toshiaki Kondo, Hideki Masuda, Hiroaki Misawa

    GREEN CHEMISTRY   19 ( 10 )   2398 - 2405   2017年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    In this study, we developed a three-dimensional plasmonic photoanode using titanium dioxide nanotunnels (TNTs) loaded with gold nanoparticles (Au-NPs) for water splitting, to enhance the reaction efficiency. We also optimized the procedure of loading Au-NPs on complex three-dimensional structures. We discuss the correlation between the plasmon-induced charge separation obtained from photoelectrochemical measurement and the morphology of Au-NPs observed by transmission electron microscopy. We have successfully deposited well-dispersed Au-NPs on the walls of TNTs using HAu(OH)(4) as a precursor. The amount of Au-NPs on the TNTs was estimated to be approximately 15-fold larger than that on the thin film titanium dioxide substrate, and the particle size remained small. Photoelectrochemical water splitting was achieved by using a two-electrode system rather than a three-electrode system. Furthermore, stoichiometric water splitting was confirmed by estimating the amounts of the evolved H-2 and O-2 gases under visible light irradiation.

    DOI: 10.1039/c6gc03217f

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  • Plasmon-induced photoelectrochemical biosensor for in situ real-time measurement of biotin-streptavidin binding kinetics under visible light irradiation 査読

    Jingchun Guo, Tomoya Oshikiri, Kosei Ueno, Xu Shi, Hiroaki Misawa

    ANALYTICA CHIMICA ACTA   957   70 - 75   2017年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We developed a localized surface plasmon-induced visible light-responsive photoelectrochemical (PEC) biosensor using a titanium dioxide (TiO2) photoelectrode loaded with gold nanoislands (AuNIs) for in situ real-time measurement of biotin-streptavidin association. As a proof of concept, self-assembled thiol-terminated biotin molecules bound on a AuNls/TiO2 photoelectrode were successfully utilized to explore the photocurrent response to streptavidin-modified gold nanoparticle (STA-AuNP) solutions. This plasmon-induced PEC biosensor is simple and easy to miniaturize. Additionally, the PEC biosensor achieves highly sensitive measurements under only visible light irradiation and prevents the UV-induced damage of samples. Furthermore, a novel approach has been proposed to realize the real-time monitoring of biotin-STA binding affinities and kinetics by analyzing the PEC sensing characteristics. This PEC biosensor and novel analysis method could provide a new approach for the specific electrical detection and real-time kinetic measurements for clinical diagnostics and drug development. (C) 2016 The Authors. Published by Elsevier B.V.

    DOI: 10.1016/j.aca.2016.12.025

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  • Near-field spectroscopic properties of complementary gold nanostructures: applicability of Babinet's principle in the optical region 査読

    Hidetoshi Mizobata, Kosei Ueno, Hiroaki Misawa, Hiromi Okamoto, Kohei Imura

    OPTICS EXPRESS   25 ( 5 )   5279 - 5289   2017年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    We examine the far-field and near-field properties of complementary screens made of nanostructured gold thin films, a rectangular nanowire and a nanovoid, using an aperture-type scanning near-field optical microscope and electromagnetic field calculations, and discuss the applicability of Babinet's principle in the optical region. The far-field transmission spectra of the complementary screens are considerably different from each other. On the other hand, genuine near-field extinction spectra exhibit nearly complementary characteristics. The spatial features of the observed near-field images for the complementary screens show little correlation. We have found from the Fourier analysis of the simulated images that high spatial-frequency components of the electromagnetic fields show mutual spatial correlation. These results suggest that Babinet's principle is applicable to the high spatial-frequency components of electromagnetic fields for the complementary screens. (C) 2017 Optical Society of America

    DOI: 10.1364/OE.25.005279

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  • Near-field spectral properties of coupled plasmonic nanoparticle arrays 査読

    Han Yu, Quan Sun, Jinghuan Yang, Kosei Ueno, Tomoya Oshikiri, Atsushi Kubo, Yasutaka Matsuo, Qihuang Gong, Hiroaki Misawa

    OPTICS EXPRESS   25 ( 6 )   6883 - 6894   2017年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    We investigated the grating effect in complex gold dolmen structures, in which multiple plasmon modes are present due to plasmon hybridization, experimentally from both the far field and the near field. In particular, the near-field properties were investigated using photoemission electron microscopy, and it was demonstrated that two hybridized plasmon modes on the dolmen structures could be influenced by the grating effect. For comparison, we also investigated the grating effect in arrays of simple nanoblocks and heptamer structures, which were supposed to support a strong bright plasmon mode and a strong dark plasmon mode, respectively, in the near field. We found that the spectral responses of the two hybridized modes on the dolmen structures as the pitch size changed evolved in a manner similar to that of the bright dipole mode on the nanoblocks, whereas the dark mode on the heptamer structures is less sensitive to the pitch size. (C) 2017 Optical Society of America

    DOI: 10.1364/OE.25.006883

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  • Highly Sensitive Aluminum-Based Biosensors using Tailorable Fano Resonances in Capped Nanostructures 査読

    Kuang-Li Lee, Hsuan-Yeh Hsu, Meng-Lin You, Chia-Chun Chang, Ming-Yang Pan, Xu Shi, Kosei Ueno, Hiroaki Misawa, Pei-Kuen Wei

    SCIENTIFIC REPORTS   7   2017年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:NATURE PUBLISHING GROUP  

    Metallic nanostructure-based surface plasmon sensors are capable of real-time, label-free, and multiplexed detections for chemical and biomedical applications. Recently, the studies of aluminum-based biosensors have attracted a large attention because aluminum is a more cost-effective metal and relatively stable. However, the intrinsic properties of aluminum, having a large imaginary part of the dielectric function and a longer evanescent length, limit its sensing capability. Here we show that capped aluminum nanoslits fabricated on plastic films using hot embossing lithography can provide tailorable Fano resonances. Changing height of nanostructures and deposited metal film thickness modulated the transmission spectrum, which varied from Wood's anomaly-dominant resonance, asymmetric Fano profile to surface plasmon-dominant resonance. For biolayer detections, the maximum surface sensitivity occurred at the dip of asymmetric Fano profile. The optimal Fano factor was close to -1.3. The wavelength and intensity sensitivities for surface thickness were up to 2.58 nm/nm and 90%/nm, respectively. The limit of detection (LOD) of thickness reached 0.018 nm. We attributed the enhanced surface sensitivity for capped aluminum nanoslits to a reduced evanescent length and sharp slope of the asymmetric Fano profile. The protein-protein interaction experiments verified the high sensitivity of capped nanostructures. The LOD was down to 236 fg/mL.

    DOI: 10.1038/srep44104

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  • Versatile plasmonic-effects at the interface of inverted perovskite solar cells 査読

    Ahmed Esmail Shalan, Tomoya Oshikiri, Hiroki Sawayanagi, Keisuke Nakamura, Kosei Ueno, Quan Sun, Hui-Ping Wu, Eric Wei-Guang Diau, Hiroaki Misawa

    NANOSCALE   9 ( 3 )   1229 - 1236   2017年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    Plasmonics is a highly promising approach to enhancing the light-harvesting properties of hybrid organic/ inorganic perovskite solar cells. In the present work, our cells have a p-i-n inverted planar structure. An ultrathin NiO film with two different thicknesses of 5 and 10 nm prepared by a pulsed laser deposition process on an ITO substrate with a faceted and furrowed surface enabled the formation of a continuous and compact layer of well-crystallized CH3NH3PbI3 via an anti-solvent chlorobenzene process. The coverage mechanism of the NiO film on the ITO was clearly demonstrated through the J-V and external quantum efficiency (EQE) curves. Moreover, the results demonstrated that the gold nanoislands (Au NIs) increased the power conversion efficiency to 5.1%, almost double that of the samples without Au NIs. This result is due to the excitation of surface plasmons, which is characterized by strong scattering and enhancement of the electric field in the vicinity of the Au NIs loaded at the interface between the NiO and perovskite films. Additionally, we observed an enhancement of the EQE at wavelengths shorter than the plasmon resonance peak. In the current state, we speculate that the plasmoelectric potential effect is considered to be a good explanation of the photocurrent enhancement at the off-resonance region. Our work provides good guidance for the design and fabrication of solar-energy-related devices employing NiO electrodes and plasmonic Au NIs.

    DOI: 10.1039/c6nr06741g

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  • Optimization of a compact layer of TiO2via atomic-layer deposition for high-performance perovskite solar cells 査読

    Ahmed Esmail Shalan, Sudhakar Narra, Tomoya Oshikiri, Kosei Ueno, Xu Shi, Hui-Ping Wu, Mahmoud~M. Elshanawany, Eric Wei-Guang Diau, Hiroaki Misawa

    Sustainable Energy Fuels   2017年

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    出版者・発行元:Royal Society of Chemistry ({RSC})  

    DOI: 10.1039/C7SE00220C

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  • Enhancing surface sensitivity of nanostructure-based aluminum sensors using capped dielectric layers 査読

    Kuang-Li Lee, Po-Cheng Tsai, Meng-Lin You, Ming-Yang Pan, Xu Shi, Kosei Ueno, Hiroaki Misawa, Pei-Kuen Wei

    ACS Omega   2 ( 10 )   7461 - 7470   2017年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society  

    The studies of nanostructure-based aluminum sensors have attracted huge attention because aluminum is a more cost-effective plasmonic material. However, the intrinsic properties of the aluminum metal, having a large imaginary part of the dielectric function and a longer electromagnetic field decay length and problems of poor long-term chemical stability, limit the surface-sensing capability and applicability of nanostructures. We propose the combination of capped aluminum nanoslits and a thin-capped dielectric layer to overcome these limitations. We show that the dielectric layer can positively enhance the wavelength sensitivities of the Wood's anomaly-dominant resonance and asymmetric Fano resonance in capped aluminum nanoslits. The maximum improvement can be reached by a factor of 3.5. Besides, there is an optimal layer thickness for the surface sensitivity because of the trade-off relationship between the refractive index sensitivity and decay length. We attribute the enhanced surface sensitivity to a reduced evanescent length, which is confirmed by the finite difference time-domain calculations. The protein-protein interaction experiments verify the high-surface sensitivity of the structures, and a limit of quantification (LOQ) of 1 pg/mL antibovine serum albumin is achieved. Such low-cost, highly sensitive aluminum-based nanostructures can benefit various sensing applications.

    DOI: 10.1021/acsomega.7b01349

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  • Cobalt Oxide (CoOx) as an Efficient Hole-Extracting Layer for High Performance Inverted Planar Perovskite Solar Cells 査読

    Ahmed Esmail Shalan, Tomoya Oshikiri, Sudhakar Narra, Mahmoud M. Elshanawany, Kosei Ueno, Hui-Ping Wu, Keisuke Nakamura, Xu Shi, Eric Wei-Guang Diau, Hiroaki Misawa

    ACS APPLIED MATERIALS & INTERFACES   8 ( 49 )   33592 - 33600   2016年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    CoOx is a promising hole-extracting layer (HEL) for inverted planar perovskite solar cells with device configuration ITO/CoOx/CH3NH3PbI3/PCBM/Ag. The devices fabricated according to a simple solution procedure showed the best photovoltaic performance attaining power conversion efficiency (PCE) of 14.5% under AM 1.5 G 1 sun irradiation, which is significantly superior to those of materials fabricated with a traditional HEL such as PEDOT:PSS (12.2%), NiOx (10.2%), and CuOx (9.4%) under the same experimental conditions. We characterized the chemical compositions with XPS, crystal structures with XRD, and film morphology with SEM/AFM techniques. Photoluminescence (PL) spectra and the corresponding PL decays for perovskite deposited on varied HEL films were recorded to obtain the hole-extracting characteristics, for which the hole extracting times show the order CoOx (2.8 ns) &lt; PEDOT:PSS (17.5 ns) &lt; NiOx (22.8 ns) &lt; CuOx (208.5 ns), consistent with the trend of their photovoltaic performances. The reproducibility and enduring stability of those devices were examined to show the outstanding long-term stability of the devices made of metal oxide HEL, for which the CoOx device retained PCE approximate to 12% for over 1000 h.

    DOI: 10.1021/acsami.6b10803

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  • Exploring Coupled Plasmonic Nanostructures in the Near Field by Photoemission Electron Microscopy 査読

    Han Yu, Quan Sun, Kosei Ueno, Tomoya Oshikiri, Atsushi Kubo, Yasutaka Matsuo, Hiroaki Misawa

    ACS NANO   10 ( 11 )   10373 - 10381   2016年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    The extraordinary optical properties of coupled plasmonic nanostructures make these materials potentially useful in many applications; thus, they have received enormous attention in basic and applied research. Coupled plasmon modes have been characterized predominantly using far-field spectroscopy. In near-field spectroscopy, the spectral response of local field enhancement in coupled plasmonic nanostructures remains largely unexplored, especially experimentally. Here, we investigate the coupled gold dolmen nanostructures in the near field using photoemission electron microscopy, with wavelength tunable femtosecond laser pulses as an excitation source. The spatial evolution of near-field mapping of an individual dolmen structure with the excitation wavelength was successfully obtained. In the near field, we spatially resolved an anti-bonding mode and a bonding mode as the result of plasmon hybridization. Additionally, the quadrupole plasmon mode that could be involved in the formation of a Fano resonance was also revealed by spatially resolved near-field spectra, but it only contributed little to the total near-field enhancement. On the basis of these findings, we obtained a better understanding of the near-field nanostructures, where the plasmon hybridization and the plasmonic Fano resonance were mixed.

    DOI: 10.1021/acsnano.6b06206

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  • Surface plasmon optical antennae in the infrared region with high resonant efficiency and frequency selectivity 査読

    Kosei Ueno, Quan Sun, Masahiro Mino, Takumi Itoh, Tomoya Oshikiri, Hiroaki Misawa

    OPTICS EXPRESS   24 ( 16 )   17728 - 17737   2016年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    Infrared light has received attention for sensor applications, including fingerprint spectroscopy, in the bioengineering and security fields. Surface plasmon physics enables the operation of a light harvesting optical antenna. Gold nanochains exhibit localized surface plasmon resonance (LSPR) in the infrared region with high frequency selectivity. However, a feasible design for optical antennae with a higher resonant efficiency and frequency selectivity as a function of structural design and periodicity is still unknown. In the present study, we investigated the relationship between the resonant efficiency and frequency selectivity as a function of the structural design of gold nanochains and explored structural periodicity for obtaining highly frequency-selective optical antennae. An optical antenna design with higher resonant efficiency is proposed on the basis of its efficient interaction with non-polarized light. (C) 2016 Optical Society of America

    DOI: 10.1364/OE.24.017728

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  • Dual Strong Couplings Between TPPS J-Aggregates and Aluminum Plasmonic States 査読

    Jie Li, Kosei Ueno, Hiyori Uehara, Jingchun Guo, Tomoya Oshikiri, Hiroaki Misawa

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   7 ( 14 )   2786 - 2791   2016年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We report on the spectral properties of strong coupling between the localized surface plasmon resonances (LSPRs) of aluminum (Al) nanostructures and tetraphenylporphyrin tetrasulfonic acid hydrate (TPPS) J-aggregates. Because of their wide spectral range of LSPR bands from ultraviolet to near-infrared wavelengths by controlling structural size, Al nanodisks can realize strong coupling with different excitons of TPPS J-aggregates. The Rabi splitting energies of the excitons based on Soret and Qbands are 300 and 180 meV, respectively. In addition to extinction spectrum, we have also measured an excitation spectrum to determine the essential absorption of the hybrid states and successfully confirmed a shoulder peak corresponding to a lower branch of hybrid states. In Al nanorod systems, strong coupling with two excitons can also be selectively induced by merely rotating the polarization of the incident light, which constituted a simple platform for the dynamic control of exciton/plasmon coupling states.

    DOI: 10.1021/acs.jpclett.6b01224

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  • Spectroscopic properties of gold curvilinear nanorod arrays 査読

    Yukie Yokota, Kosei Ueno, Hiroaki Misawa, Takuo Tanaka

    Photonics   3 ( 2 )   2016年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:MDPI AG  

    We designed and fabricated gold curvilinear nanorod periodical arrays using microfabrication techniques. The gold curvilinear nanorods had two distinct resonant peaks in the near-infrared region between 1630 nm and 3000 nm. Similar peak was observed in gold straight nanorods at specific lengths. At lengths identical to the arc length of the curvilinear nanorod, the peak was in the relative range of 3000 nm, which corresponds to the longitudinal plasmon mode (L-mode). At lengths identical to half of the arc length of the curvilinear nanorod, the peak was close to 1630 nm. Plasmon resonant peaks were tunable in the infrared region by changing the arc length of the curve, the line width, and distance between the curvilinear nanorods. In particular, when two curvilinear nanorods were closely packed in a range of less than 100 nm, the peak wavelength of curvilinear nanorod was shifted due to the plasmonic coupling of each mode.

    DOI: 10.3390/photonics3020018

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    その他リンク: http://orcid.org/0000-0003-1070-387X

  • Selective Dinitrogen Conversion to Ammonia Using Water and Visible Light through Plasmon-induced Charge Separation 査読

    Tomoya Oshikiri, Kosei Ueno, Hiroaki Misawa

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   55 ( 12 )   3942 - 3946   2016年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    The generation of ammonia from atmospheric nitrogen and water using sunlight is a preferable approach to obtaining ammonia as an energy carrier and potentially represents a new paradigm for achieving a low-carbon and sustainable-energy society. Herein, we report the selective conversion of dinitrogen into ammonia through plasmon-induced charge separation by using a strontium titanate (SrTiO3) photoelectrode loaded with gold nanoparticles (Au-NPs) and a zirconium/zirconium oxide (Zr/ZrOx) thin film. We observed the simultaneous stoichiometric production of ammonia and oxygen from nitrogen and water under visible-light irradiation.

    DOI: 10.1002/anie.201511189

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  • Spectral response and spatial evolution of plasmonic near field in coupled gold nanostructures

    Han,Yu, Quan,Sun, Oshikiri,T, Ueno,Kosei, Kubo,Atsushi, Matsuo,Yasutaka, Misawa,Hiroaki

    日本化学会第96春季年会 予稿集   4E3-12   2016年3月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

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  • Properties of Plasmon-Induced Photoelectric Conversion on a TiO2/NiO p-n Junction with Au Nanoparticles 査読

    Keisuke Nakamura, Tomoya Oshikiri, Kosei Ueno, Yongming Wang, Yoshiomi Kamata, Yuki Kotake, Hiroaki Misawa

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   7 ( 6 )   1004 - 1009   2016年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We have successfully fabricated all-solid-state plasmonic photoelectric conversion devices composed of titanium dioxide (TiO2)/nickel oxide (NiO) p-n junctions with gold nanoparticles (Au-NPs) as prototype devices for a plasmonic solar cell. The characteristics of the crystal structures and the photoelectric properties of the all-solid-state devices were demonstrated. We observed that the crystalline structure of the NiO thin film and the interfacial structure of TiO2/Au-NPs/NiO changed significantly during an annealing treatment. Furthermore, the photoelectric conversion devices exhibited plasmon-induced photocurrent generation in the visible-wavelength region. The photo current may result from plasmon-induced charge separation. The photoelectric conversion properties via plasmon-induced charge separation were strongly correlated with the morphology of the TiO2/Au-NPs/NiO interface. The long-term stability of the plasmonic photoelectric conversion device was found to be very high because a stable photocurrent was observed even after irradiation for 3 days.

    DOI: 10.1021/acs.jpclett.6b00291

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  • Dissecting the Few-Femtosecond Dephasing Time of Dipole and Quadrupole Modes in Gold Nanoparticles Using Polarized Photoemission Electron Microscopy 査読

    Quan Sun, Han Yu, Kosei Ueno, Atsushi Kubo, Yasutaka Matsuo, Hiroaki Misawa

    ACS NANO   10 ( 3 )   3835 - 3842   2016年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Dipole and quadrupole modes are the two lowest orders of localized surface plasmon resonance (LSPR) eigenmodes in metallic nanoparticles. Of these two modes, the quadrupole mode is forbidden for symmetric metallic nanoparticles excited by linearly polarized light at normal incidence. Here, we demonstrate excitation of the quadrupole mode in symmetrical gold (Au) nanoblocks shined with s -polarized light at oblique incidence. In particular, we probe the near -field LSPR in Au nanoblocks using photoemission electron microscopy (PEEM) and find that at oblique incidence, the dipole and quadrupole modes can be selectively excited, in terms of near -field enhancement, by manipulating the light polarization state. More importantly, by time -resolved PEEM measurements, we experimentally demonstrate that the quadrupole mode in symmetrical Au nanoblocks has longer dephasing time than that of the dipole mode.

    DOI: 10.1021/acsnano.6b00715

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  • Plasmon-Induced Water Splitting Using Metallic-Nanoparticle-Loaded Photocatalysts and Photoelectrodes 査読

    Kosei Ueno, Tomoya Oshikiri, Hiroaki Misawa

    CHEMPHYSCHEM   17 ( 2 )   199 - 215   2016年1月

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    記述言語:英語   出版者・発行元:WILEY-V C H VERLAG GMBH  

    Visible- and near-infrared-light-driven water splitting, which splits water molecules to generate hydrogen and oxygen gases, is a significant subject in artificial photosynthesis with the goal of achieving a low-carbon society. In recent years, considerable attention has been paid to studies on the development of a plasmon-induced water-splitting system responding to visible light. In this review, we categorized water-splitting systems as gold-nanoparticle-loaded semiconductor photocatalytic particles system and metallic-nanoparticles-loaded semiconductor photoelectrode systems, and introduce the latest studies according to these categories. Especially, we describe the studies that optimize a material or a structural design of metallic-nanoparticle-loaded semiconductor photoelectrodes and consider a whole water-splitting system, including a cathode design. Furthermore, we discuss important points when studying plasmon-induced water splitting, and we describe a methodology that enhances plasmon-induced water-splitting efficiency.

    DOI: 10.1002/cphc.201500761

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  • Fano resonances on gold nano dolmen structures probed by photoemission electron microscopy

    Han,Yu, Quan,Sun, Ueno,Kosei, Kubo,Atsushi, Matsuo,Yasutaka, Misawa,Hiroaki

    Pacifichem 2015   2015年12月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

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  • Exploring plasmonic hot spots and their dynamics by photoemission electron microscopy

    Quan,Sun, Han,Yu, Ueno,Kosei, Kubo,Atsushi, Matsuo,Yasutaka, Misawa,Hiroaki

    Pacifichem 2015   2015年12月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

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  • Surface-enhanced terahertz spectroscopy using gold rod structures resonant with terahertz waves 査読

    Kosei Ueno, Sho Nozawa, Hiroaki Misawa

    Optics Express   23 ( 22 )   28584 - 28592   2015年11月

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    記述言語:英語   出版者・発行元:OSA - The Optical Society  

    Terahertz (THz) spectroscopy is a promising method to measure the spectrum of low-frequency modes of molecules or ensembles, such as crystals and polymers, including proteins. However, the main drawback of THz spectroscopy is its extremely low sensitivity. In the present study, we report on signal enhancement in THz spectroscopy achieved by depositing amino acid molecules or their derivatives on a gold rod structured silicon substrate whose localized surface plasmon resonance is exhibited in the THz frequency region. The distinct peaks derived from the enhancement of the inherent spectrum based on a molecular crystal were clearly observed when a longitudinal plasmon resonance mode of the gold rod structure was excited and the plasmon resonance band overlapped the molecular/intermolecular vibrational mode. We discuss the mechanism by which surface-enhanced THz spectroscopy was induced from the viewpoint of the enhancement of light-matter coupling due to plasmon excitation and the modulation of the plasmon band by dipole coupling between the plasmon dipole and molecular/intermolecular vibrational modes.

    DOI: 10.1364/OE.23.028584

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    その他リンク: http://orcid.org/0000-0002-4882-7854

  • Plasmon-induced artificial photosynthesis 査読

    Kosei Ueno, Tomoya Oshikiri, Xu Shi, Yuqing Zhong, Hiroaki Misawa

    INTERFACE FOCUS   5 ( 3 )   20140082   2015年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC  

    We have successfully developed a plasmon-induced artificial photosynthesis system that uses a gold nanoparticle-loaded oxide semiconductor electrode to produce useful chemical energy as hydrogen and ammonia. The most important feature of this system is that both sides of a strontium titanate single-crystal substrate are used without an electrochemical apparatus. Plasmon-induced water splitting occurred even with a minimum chemical bias of 0.23 V owing to the plasmonic effects based on the efficient oxidation of water and the use of platinum as a co-catalyst for reduction. Photocurrent measurements were performed to determine the electron transfer between the gold nanoparticles and the oxide semiconductor. The efficiency of water oxidation was determined through spectroelectrochemical experiments aimed at elucidating the electron density in the gold nanoparticles. A set-up similar to the water-splitting system was used to synthesize ammonia via nitrogen fixation using ruthenium instead of platinum as a co-catalyst.

    DOI: 10.1098/rsfs.2014.0082

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  • Plasmon-enhanced light energy conversion using gold nanostructured oxide semiconductor photoelectrodes 査読

    Kosei Ueno, Tomoya Oshikiri, Kei Murakoshi, Haruo Inoue, Hiroaki Misawa

    PURE AND APPLIED CHEMISTRY   87 ( 6 )   547 - 555   2015年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WALTER DE GRUYTER GMBH  

    We have successfully demonstrated plasmon-enhanced photocurrent generation using gold nan-oparticle- loaded titanium dioxide single-crystal (TiO2) photoelectrodes with visible-light irradiation. Water molecules serve as an electron source in photocurrent generation, and oxygen evolution occurs due to water oxidation from a gold nanostructured TiO2 photoelectrode as a half reaction of water splitting. On the basis of this property, the photocurrent generation system was applied to the plasmon-induced water-splitting system using both sides of the same strontium titanate (SrTiO3) single-crystal substrate without an electrochemical apparatus. The chamber on the side of the gold nanoparticles was the anode side, whereas the chamber on the side of the platinum plate was the cathode side. Platinum was used as a co-catalyst for hydrogen evolution. Hydrogen and oxygen were separately evolved from the anode and cathode chambers, respectively. Water splitting was induced with a relatively low chemical bias of 0.23 V due to plasmonic effects based on efficient water oxidation. Similar to the artificial photosynthesis system, we have also demonstrated ammonia formation via nitrogen fixation using ruthenium as a co-catalyst via an analogous setup of the water-splitting system.

    DOI: 10.1515/pac-2014-1120

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  • Plasmon-enhanced Water Splitting Utilizing the Heterojunction Synergistic Effect between SrTiO3 and Rutile-TiO2 査読

    Yuqing Zhong, Kosei Ueno, Yuko Mori, Tomoya Oshikiri, Hiroaki Misawa

    CHEMISTRY LETTERS   44 ( 5 )   618 - 620   2015年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    A plasmon-enhanced water splitting system using a gold nanostructured strontium titanate (SrTiO3) single-crystal photoelectrode with a titanium dioxide (TiO2) thin film heterojunction was developed. Simultaneous evolution of hydrogen and oxygen was observed in separate reaction chambers under visible light irradiation. The substrate composed of single-crystal SrTiO3 with a rutile TiO2 thin film heterojunction exhibited enhanced water splitting activity compared with the electrode without the TiO2 thin film because the synergistic effect may prevent the back-electron-transfer reaction.

    DOI: 10.1246/cl.150028

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  • Cocatalyst Effects on Hydrogen Evolution in a Plasmon-Induced Water-Splitting System 査読

    Yuqing Zhong, Kosei Ueno, Yuko Mori, Tomoya Oshikiri, Hiroaki Misawa

    JOURNAL OF PHYSICAL CHEMISTRY C   119 ( 16 )   8889 - 8897   2015年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We explored the performance of hydrogen (H-2) evolution using noble metals or their metal oxides as cocatalysts in the plasmon-induced water-splitting system. Although many studies have employed n-type semiconductor particle systems to investigate cocatalyst effects, evaluating only the catalytic activity of H-2 and oxygen (O-2) evolution has been limited by (1) the difficulty of transferring an electron injected into the conduction band of a semiconductor to a cocatalyst due to the formation of a Schottky barrier when a metallic cocatalyst for H2 evolution contacts the n-type semiconductor and (2) the potential for a reverse water-splitting reaction, which occurs due to the promotion of the reduction of the evolved O-2 by the cocatalyst. To overcome these limitations, in the present study, we eliminated the adverse effect of the Schottky barrier by obtaining ohmic contact between the semiconductor and the metal or metal oxide cocatalysts, and we used two separate reaction chambers for H-2 and O-2 evolution to avoid reverse water-splitting reactions such as H2O2 recombination or the photoreduction of O-2. A 23 nm thick rhodium layer deposited on a platinum board exhibited relatively high performance, a 3-fold increase compared with the absence of a metal or metal oxide cocatalyst thin layer.

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  • Plasmon-Assisted Water Splitting Using Two Sides of the Same SrTiO3 Single-Crystal Substrate: Conversion of Visible Light to Chemical Energy 査読

    Yuqing Zhong, Kosei Ueno, Yuko Mori, Xu Shi, Tomoya Oshikiri, Kei Murakoshi, Haruo Inoue, Hiroaki Misawa

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   53 ( 39 )   10350 - 10354   2014年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    A plasmon-induced water splitting system that operates under irradiation by visible light was successfully developed; the system is based on the use of both sides of the same strontium titanate (SrTiO3) single-crystal substrate. The water splitting system contains two solution chambers to separate hydrogen (H-2) and oxygen (O-2). To promote water splitting, a chemical bias was applied by regulating the pH values of the chambers. The quantity of H-2 evolved from the surface of platinum, which was used as a reduction co-catalyst, was twice the quantity of O-2 evolved from an Au-nanostructured surface. Thus, the stoichiometric evolution of H-2 and O-2 was clearly demonstrated. The hydrogen-evolution action spectrum closely corresponds to the plasmon resonance spectrum, indicating that the plasmon-induced charge separation at the Au/SrTiO3 interface promotes water oxidation and the subsequent reduction of a proton on the backside of the SrTiO3 substrate. The chemical bias is significantly reduced by plasmonic effects, which indicates the possibility of constructing an artificial photosynthesis system with low energy consumption.

    DOI: 10.1002/anie.201404926

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  • Exploring quadrupole and higher order surface plasmon resonances in individual plasmonic nanoantennas by PEEM

    Q.,Sun, H.,Yu, K.,Ueno, Kubo,Atsushi, Y.,Matsuo, H.,Misawa

    LEEM/PEEM 9 Book of Abttracts   75 - 75   2014年9月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:Forschungszentrum Jülich GmbH  

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  • Plasmon-Induced Ammonia Synthesis through Nitrogen Photofixation with Visible Light Irradiation 査読

    Tomoya Oshikiri, Kosei Ueno, Hiroaki Misawa

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   53 ( 37 )   9802 - 9805   2014年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    We have successfully developed a plasmon-induced technique for ammonia synthesis that responds to visible light through a strontium titanate (SrTiO3) photoelectrode loaded with gold (Au) nanoparticles. The photoelectrochemical reaction cell was divided into two chambers to separate the oxidized (anodic side) and reduced (cathodic side) products. To promote NH3 formation, a chemical bias was applied by regulating the pHvalue of these compartments, and ethanol was added to the anodic chamber as a sacrificial donor. The quantity of NH3 formed at the ruthenium surface, which was used as a co-catalyst for SrTiO3, increases linearly as a function of time under irradiation with visible light at wavelengths longer than 550nm. The NH3 formation action spectrum approximately corresponds to the plasmon resonance spectrum. We deduced that plasmon-induced charge separation at the Au/SrTiO3 interface promotes oxidation at the anodic chamber and subsequent nitrogen reduction on the cathodic side.

    DOI: 10.1002/anie.201404748

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  • Surface-Plasmon-Mediated Programmable Optical Nanofabrication of an Oriented Silver Nanoplate 査読

    Bin-Bin Xu, Lei Wang, Zhuo-Chen Ma, Ran Zhang, Qi-Dai Chen, Chao Lv, Bing Han, Xin-Ze Xiao, Xu-Lin Zhang, Yong-Lai Zhang, Kosei Ueno, Hiroaki Misawa, Hong-Bo Sun

    ACS NANO   8 ( 7 )   6682 - 6692   2014年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We report polarized femtosecond laser-light-mediated growth and programmable assembly of photoreduced silver nanoparticles into triply hierarchical micropatterns. Formation of erected arrays of nanoplates with a thickness as small as lambda/27 (lambda, the writing laser wavelength) level is demonstrated. The growth mechanism of nanoplates has been clarified: (i) the excited surface plasmons enhance the local electric field and lead to spatially selective growth of silver atoms at the opposite ends of dipoles induced on early created silver seeds; (ii) the optical attractive force overcomes electrostatic repulsion in the enhanced local electric field to assemble the silver nanoparticles directly. The triply hierarchical micropattern shape and location, the nanoplate orientation, and thickness are all attained in controlled fashion.

    DOI: 10.1021/nn5029345

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  • Robust and Versatile Light Absorption at Near-Infrared Wavelengths by Plasmonic Aluminum Nanorods 査読

    Olivier Lecarme, Quan Sun, Kosei Ueno, Hiroaki Misawa

    ACS PHOTONICS   1 ( 6 )   538 - 546   2014年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We investigate the far-field and near-field properties of aluminum nanorods fabricated by electron beam lithography and exhibiting plasmonic resonance in the near-infrared region. First, we show that plasmonic modes within nanorod arrays can be tuned by geometrical parameters, allowing one to control the system transparency. Next, the light absorption in this structure is closely examined, and we demonstrate that aluminum has great potential due to its unique interband transition at 800 nm. The roles of the dielectric confinement and the coupling between plasmonic resonance and the interband transition are particularly emphasized, as their adjustment can be used to switch from highly scattering particles to absorbing particles without a significant modification of the plasmonic resonance position. Finally, we image the plasmon-generated local field distribution in the aluminum nanostructures and observe, for the first time, the effect of the interband transition on the near-field behavior. The effect of the dielectric confinement is also numerically investigated, as it is shown to play a significant role in near-field enhancement.

    DOI: 10.1021/ph500096q

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  • Plasmon modes in single gold nanodiscs 査読

    K. Imura, K. Ueno, H. Misawa, H. Okamoto, D. McArthur, B. Hourahine, F. Papoff

    OPTICS EXPRESS   22 ( 10 )   12189 - 12199   2014年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    Optical properties of single gold nanodiscs were studied by scanning near-field optical microscopy. Near-field transmission spectra of a single nanodisc exhibited multiple plasmon resonances in the visible to near-infrared region. Near-field transmission images observed at these resonance wavelengths show wavy spatial features depending on the wavelength of observation. To clarify physical pictures of the images, theoretical simulations based on spatial correlation between electromagnetic fundamental modes inside and outside of the disc were performed. Simulated images reproduced the observed spatial structures excited in the disc. Mode-analysis of the simulated images indicates that the spatial features observed in the transmission images originate mainly from a few fundamental plasmon modes of the disc. (C) 2014 Optical Society of America

    DOI: 10.1364/OE.22.012189

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  • Revealing higher order surface plasmon resonances and their dynamics by PEEM

    Quan,Sun, Han,Yu, Kosei,Ueno, Kubo,Atsushi, Yasutaka,Matsuo, Hiroaki,Misawa

    第61回応用物理学会春季学術講演会 講演予稿集   2014年3月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

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  • Photoelectrochemical Behavior of Self-Assembled Ag/Co Plasmonic Nanostructures Capped with TiO2 査読

    Anri Watanabe, Yuki Kotake, Yoshiomi Kamata, Akira Chikamatsu, Kosei Ueno, Hiroaki Misawa, Tetsuya Hasegawa

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   5 ( 1 )   25 - 29   2014年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    The use of localized surface plasmon resonance induced by Ag nanostructures is a promising way for high-efficiency photoelectric conversion. In plasmonic photoelectric conversion devices, however, the chemical instability of Ag in ambient atmosphere and its immediate deterioration have been a critical issue. Here, we propose a Ag-Co nanostructure array embedded in a TiO2 matrix as a plasmonic resonator that ensures long-term stability. We also developed an electrochemical process to remove surface Co nanoclusters protecting fresh Ag from exposure to air. This enabled us to "unseal" Ag at the desired time. Furthermore, we confirmed photoelectric conversion using Ag-Co-TiO2 nanocomposite films in contact with solution; the photoelectric conversion was substantially enhanced by the plasmon resonance of the Ag nanorods. The Ag nanostructures sealed in a TiO2 matrix are expected to be used in other application fields, such as catalytisis and sensing, in which a fresh Ag surface is needed.

    DOI: 10.1021/jz402320p

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  • Surface-enhanced Raman scattering of crystal violets from periodic array of gold nanocylinders 査読

    Gang Bi, Li Wang, Chunfeng Cai, Kosei Ueno, Hiroaki Misawa, Jianrong Qiu

    JOURNAL OF MODERN OPTICS   61 ( 15 )   1231 - 1235   2014年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:TAYLOR & FRANCIS LTD  

    The periodic arrays of gold nanocylinder with 121 nm in diameter, 6.3 nm in gap, and 34 nm in thickness are fabricated on glass by electron-beam lithography and lift-off techniques. Some crystal violet molecules are coated on the array by using the dipping and drawing method. In addition, the surface-enhanced Raman scattering (SERS) spectra of these samples with and without gold nanocylinder arrays are characterized specifically. The largest enhancement factor is obtained when the excitation wavelength corresponds to the peak wavelength of localized surface plasmon resonance (LSPR). The density functional theory and the finite-difference time-domain method are used for the calculations of the extinction spectrum of the arrays and Raman spectra of the crystal violet, respectively. These results unambiguously demonstrate that the periodic arrays of gold nanocylinder have good and effective surface-enhanced properties for Raman scattering of crystal violets, and they also show that the excitation wavelength corresponding to the peak one of the LSPR is one of the major reasons causing SERS.

    DOI: 10.1080/09500340.2014.928378

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  • Direct imaging of the near field and dynamics of surface plasmon resonance on gold nanostructures using photoemission electron microscopy 査読

    Quan Sun, Kosei Ueno, Han Yu, Atsushi Kubo, Yasutaka Matsuo, Hiroaki Misawa

    LIGHT-SCIENCE & APPLICATIONS   2   e118   2013年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHINESE ACAD SCIENCES, CHANGCHUN INST OPTICS FINE MECHANICS AND PHYSICS  

    Localized surface plasmon resonance (LSPR) can be supported by metallic nanoparticles and engineered nanostructures. An understanding of the spatially resolved near-field properties and dynamics of LSPR is important, but remains experimentally challenging. We report experimental studies toward this aim using photoemission electron microscopy (PEEM) with high spatial resolution of sub-10 nm. Various engineered gold nanostructure arrays (such as rods, nanodisk-like particles and dimers) are investigated via PEEM using near-infrared (NIR) femtosecond laser pulses as the excitation source. When the LSPR wavelengths overlap the spectrum of the femtosecond pulses, the LSPR is efficiently excited and promotes multiphoton photoemission, which is correlated with the local intensity of the metallic nanoparticles in the near field. Thus, the local field distribution of the LSPR on different Au nanostructures can be directly explored and discussed using the PEEM images. In addition, the dynamics of the LSPR is studied by combining interferometric time-resolved pump-probe technique and PEEM. Detailed information on the oscillation and dephasing of the LSPR field can be obtained. The results identify PEEM as a powerful tool for accessing the near-field mapping and dynamic properties of plasmonic nanostructures.

    DOI: 10.1038/lsa.2013.74

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  • Direct imaging of the near field and dynamics of surface plasmon resonance on gold nanostructures using photoemission electron microscopy 査読

    Quan Sun, Kosei Ueno, Han Yu, Atsushi Kubo, Yasutaka Matsuo, Hiroaki Misawa

    LIGHT-SCIENCE & APPLICATIONS   2   2013年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHINESE ACAD SCIENCES, CHANGCHUN INST OPTICS FINE MECHANICS AND PHYSICS  

    Localized surface plasmon resonance (LSPR) can be supported by metallic nanoparticles and engineered nanostructures. An understanding of the spatially resolved near-field properties and dynamics of LSPR is important, but remains experimentally challenging. We report experimental studies toward this aim using photoemission electron microscopy (PEEM) with high spatial resolution of sub-10 nm. Various engineered gold nanostructure arrays (such as rods, nanodisk-like particles and dimers) are investigated via PEEM using near-infrared (NIR) femtosecond laser pulses as the excitation source. When the LSPR wavelengths overlap the spectrum of the femtosecond pulses, the LSPR is efficiently excited and promotes multiphoton photoemission, which is correlated with the local intensity of the metallic nanoparticles in the near field. Thus, the local field distribution of the LSPR on different Au nanostructures can be directly explored and discussed using the PEEM images. In addition, the dynamics of the LSPR is studied by combining interferometric time-resolved pump-probe technique and PEEM. Detailed information on the oscillation and dephasing of the LSPR field can be obtained. The results identify PEEM as a powerful tool for accessing the near-field mapping and dynamic properties of plasmonic nanostructures.

    DOI: 10.1038/lsa.2013.74

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  • Direct imaging of the near field and dynamics of surface plasmon resonance on gold nanostructures using photoemission electron microscopy 査読

    Quan Sun, Kosei Ueno, Han Yu, Atsushi Kubo, Yasutaka Matsuo, Hiroaki Misawa

    LIGHT-SCIENCE & APPLICATIONS   2   2013年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHINESE ACAD SCIENCES, CHANGCHUN INST OPTICS FINE MECHANICS AND PHYSICS  

    Localized surface plasmon resonance (LSPR) can be supported by metallic nanoparticles and engineered nanostructures. An understanding of the spatially resolved near-field properties and dynamics of LSPR is important, but remains experimentally challenging. We report experimental studies toward this aim using photoemission electron microscopy (PEEM) with high spatial resolution of sub-10 nm. Various engineered gold nanostructure arrays (such as rods, nanodisk-like particles and dimers) are investigated via PEEM using near-infrared (NIR) femtosecond laser pulses as the excitation source. When the LSPR wavelengths overlap the spectrum of the femtosecond pulses, the LSPR is efficiently excited and promotes multiphoton photoemission, which is correlated with the local intensity of the metallic nanoparticles in the near field. Thus, the local field distribution of the LSPR on different Au nanostructures can be directly explored and discussed using the PEEM images. In addition, the dynamics of the LSPR is studied by combining interferometric time-resolved pump-probe technique and PEEM. Detailed information on the oscillation and dephasing of the LSPR field can be obtained. The results identify PEEM as a powerful tool for accessing the near-field mapping and dynamic properties of plasmonic nanostructures.

    DOI: 10.1038/lsa.2013.74

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  • Improvement of Plasmon-Enhanced Photocurrent Generation by Interference of TiO2 Thin Film 査読

    Xu Shi, Kosei Ueno, Tomoya Oshikiri, Hiroaki Misawa

    JOURNAL OF PHYSICAL CHEMISTRY C   117 ( 47 )   24733 - 24739   2013年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    In this study, we demonstrated an improvement in the plasmon-enhanced photocurrent generation due to Fabry-Perot interference of titanium dioxide (TiO2) thin-film electrodes loaded with Au nanoislands (Au-NIs). TiO2 thin films with thicknesses of 215-274 nm, which show obvious Fabry-Perot interference, were deposited via atomic layer deposition (ALD) onto silica glass and were modified by the deposition of Au-NIs onto their surface. Anodic plasmon-enhanced photocurrent generation was observed over the Au-NIs-loaded TiO2 thin-film photoelectrodes. The incident photon to current efficiency (IPCE) action spectra correlated strongly with the Au-NIs plasmon resonance and exhibited a strong dependence on the thickness of the TiO2 thin film. The photocurrent conversion efficiency increased when the transmission constructive interference wavelength overlapped with the Au-NIs plasmon resonance band. This work provides a simple and applicable approach for the further design of low-cost and lightweight plasmon-enhanced energy conversion devices.

    DOI: 10.1021/jp408472g

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  • Plasmon-enhanced photocurrent generation and water oxidation from visible to near-infrared wavelengths 査読

    Kosei Ueno, Hiroaki Misawa

    NPG ASIA MATERIALS   5 ( e61 )   2013年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:NATURE PUBLISHING GROUP  

    This paper presents recent investigations of plasmon-enhanced photoelectric conversion and water oxidation by visible and near-infrared light irradiation. Since the discovery of the Honda-Fujishima effect in 1972, significant efforts have been devoted to lengthening the light-energy conversion wavelength. In this context, plasmonic photoelectric conversion has been recently demonstrated at visible-to-near-infrared wavelengths without deteriorating photoelectric conversion by employing titanium dioxide (TiO2) single-crystal photoelectrodes, in which gold nanorods are elaborately arrayed on the surface. A potassium perchlorate aqueous solution was employed as an electrolyte solution without additional electron donors; thus, water molecules provided the electrons. The stoichiometric evolution of oxygen and hydrogen peroxide as a result of the four-or two-electron oxidation of water molecules, respectively, was accomplished with near-infrared light irradiation using the plasmonic optical antenna effect. As there is very little overpotential for water oxidation, these results constitute a significant advancement in this field. In addition, this photoelectric conversion system could potentially be employed in artificial photosynthesis systems that exceed the photosynthetic capabilities of plants by allowing for photoconversion over a wide range of wavelengths.

    DOI: 10.1038/am.2013.42

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  • Surface plasmon-enhanced photochemical reactions 査読

    Kosei Ueno, Hiroaki Misawa

    Journal of Photochemistry and Photobiology C: Photochemistry Reviews   15 ( 1 )   31 - 52   2013年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The electromagnetic field enhancement effect based on the excitation of localized surface plasmon resonance was developed for various photochemical reaction systems, such as nano-lithography, photovoltaic cells, photocatalysis, and water splitting systems. As with most points characteristic of these surface plasmon-enhanced photochemical reactions, spatially selective photochemical reactions can be induced and photons can be efficiently utilized, a concept that could contribute to the development of green nanotechnology. Electromagnetic field enhancement effects based on plasmon excitation have contributed not only to physical processes, such as excitation efficiency, but also to chemical processes, such as photo-induced electron transfer reactions. This review article describes advanced studies on a wide variety of surface plasmon-enhanced photochemical reactions. © 2013 Elsevier B.V.

    DOI: 10.1016/j.jphotochemrev.2013.04.001

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  • Optical properties of gold nano-bowtie structures 査読

    Gang Bi, Li Wang, Li Ling, Yukie Yokota, Yoshiaki Nishijima, Kosei Ueno, Hiroaki Misawa, Jianrong Qiu

    Optics Communications   294   213 - 217   2013年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Gold-bowtie nanostructures are fabricated by electron beam lithography and lift-off techniques. Their optical properties are investigated by both experimental studies and numerical simulations. The influence of sharpness and gap of nano-bowtie on optical properties such as extinction cross section, local electric field intensity, and surface resonance wavelength is explored. The experimental extinction spectra agree well with the simulation results. This investigation may help us to design plasmonic sub-wavelength gold-bowtie nanostructure with desired spectral properties. © 2013 Elsevier B.V.

    DOI: 10.1016/j.optcom.2012.12.080

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  • Spectral properties and electromagnetic field enhancement effects on nano-engineered metallic nanoparticles 査読

    Kosei Ueno, Hiroaki Misawa

    Physical Chemistry Chemical Physics   15 ( 12 )   4093 - 4099   2013年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Plasmonic chemistry, a new research field dedicated to understanding plasmon-enhanced photochemical reactions, has become a principal area of chemical research, especially in the field of physical chemistry. In this perspective review article, we describe our recent research regarding the development of a fabrication methodology for metallic nanostructures that exhibit localized surface plasmon resonance, the spectral properties of the fabricated metallic nanostructures and their electromagnetic field enhancement effects using two-photon-induced photoluminescence from gold nanoparticles. © 2013 the Owner Societies.

    DOI: 10.1039/c2cp43681g

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  • Near Infrared Fluorescence Enhancement by Local Surface Plasmon Resonance from Arrayed Gold Nanoblocks 査読

    F. Ito, R. Ohta, Y. Yokota, K. Ueno, H. Misawa, T. Nagamura

    Optics and Photonics Journal   3   27 - 31   2013年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Plasmon-enhanced photocurrent generation and water oxidation with a gold nanoisland-loaded titanium dioxide photoelectrode 査読

    Xu Shi, Kosei Ueno, Naoki Takabayashi, Hiroaki Misawa

    Journal of Physical Chemistry C   117 ( 6 )   2494 - 2499   2013年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Metallic nanoparticles showing localized surface plasmon resonance (LSPR) are efficient elements in the localization of light to nanometer-scale regions and enhance the light-matter interaction. We show that gold nanoisland (Au-NI)-loaded titanium dioxide (TiO2) photoelectrodes exhibited plasmon-enhanced photocurrent generation in the visible wavelength region, and the photocurrent action spectrum was corresponding to the LSPR band. The photocurrent enhancement may result from the plasmon-assisted electron transfer reaction from Au-NI to TiO2. A hole with high oxidation ability was left at the TiO2 surface states near the Au-NIs/TiO2 interface, which has the potential for photocatalytic water oxidation. The photocurrent generation efficiency of Au-NIs/TiO2 photoelectrode is highly dependent on the annealing temperature for the preparation of Au-NIs. High-resolution transmission electron microscopy and electron energy-loss spectroscopy analyses show that the interfacial structure between Au-NI and TiO2 plays a crucial role in the photocurrent generation efficiency and photocatalytic ability. © 2012 American Chemical Society.

    DOI: 10.1021/jp3064036

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  • Toward Nanostructure-Enhanced Photoenergy Conversion in the Plasmonic Chemical Reaction Field 査読

    Hiroaki Misawa, Hideki Masuda, Sunao Yamada, Kei Murakoshi

    JOURNAL OF PHYSICAL CHEMISTRY C   117 ( 6 )   2433 - 2434   2013年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

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  • Optical Field Imaging of Elongated Rectangular Nanovoids in Gold Thin Film 査読

    Kohei Imura, Kosei Ueno, Hiroaki Misawa, Hiromi Okamoto

    JOURNAL OF PHYSICAL CHEMISTRY C   117 ( 6 )   2449 - 2454   2013年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We studied optical properties of single elongated rectangular nanovoids opened on a thin gold film by scanning near-field optical microscopy. We found that the luminescence is induced via two-photon absorption of near-infrared pulses when the sample is locally photoexcited inside the void as well as on the film. The luminescence spectrum of the void shows spectral features very similar to those observed for gold nanorods and is attributable to that from gold. On the basis of the near-field two-photon excitation imaging by detecting the luminescence, we visualized the optical fields near the voids. The optical image shows a characteristic spatial feature depending on the dimension of the void. From the dose inspection of the topography and the optical images, we found that excitation probability becomes high at the metal void boundary as well as inside the void. We found an oscillating feature along the long axis of the void. The observed spatial features were qualitatively reproduced by photonic local density-of-states based on electromagnetic calculations, and we conduded that the oscillation observed inside the void is attributed to the electromagnetic modes in the void coupled with the plasmon excitations.

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  • Single molecule dynamics at a mechanically controllable break junction in solution at room temperature 査読

    Tatsuya Konishi, Manabu Kiguchi, Mai Takase, Fumika Nagasawa, Hideki Nabika, Katsuyoshi Ikeda, Kohei Uosaki, Kosei Ueno, Hiroaki Misawa, Kei Murakoshi

    Journal of the American Chemical Society   135 ( 3 )   1009 - 1014   2013年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    The in situ observation of geometrical and electronic structural dynamics of a single molecule junction is critically important in order to further progress in molecular electronics. Observations of single molecular junctions are difficult, however, because of sensitivity limits. Here, we report surface-enhanced Raman scattering (SERS) of a single 4,4′-bipyridine molecule under conditions of in situ current flow in a nanogap, by using nano-fabricated, mechanically controllable break junction (MCBJ) electrodes. When adsorbed at room temperature on metal nanoelectrodes in solution to form a single molecule junction, statistical analysis showed that nontotally symmetric b1 and b2 modes of 4,4′-bipyridine were strongly enhanced relative to observations of the same modes in solid or aqueous solutions. Significant changes in SERS intensity, energy (wavenumber), and selectivity of Raman vibrational bands that are coincident with current fluctuations provide information on distinct states of electronic and geometrical structure of the single molecule junction, even under large thermal fluctuations occurring at room temperature. We observed the dynamics of 4,4′-bipyridine motion between vertical and tilting configurations in the Au nanogap via b1 and b2 mode switching. A slight increase in the tilting angle of the molecule was also observed by noting the increase in the energies of Raman modes and the decrease in conductance of the molecular junction. © 2012 American Chemical Society.

    DOI: 10.1021/ja307821u

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  • Precisely controlled plasmonic nanostructures and its application to nanolithography 査読

    K. Ueno, H. Misawa

    ADVANCED FABRICATION TECHNOLOGIES FOR MICRO/NANO OPTICS AND PHOTONICS VI   8613   2013年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    Nanoparticles of noble metals show localized surface plasmon resonance. Plasmon resonances which are collective oscillations of conduction electrons give rise to the enhancement of electromagnetic field to the local surface of metallic nanoparticles. Therefore, various plasmonic near-field lithography systems were proposed so far. Here, we report on a plasmon-assisted nanolithography used for the fabrication of nano-patterns with nanometric accuracy. The lithography system can form deep nano-patterns on positive photoresist film using scattering component of multipole plasmon resonances as an exposure light. Two-photon-induced reaction of a photoresist enabled the formation of fine patterns even using plasmonic scattering light.

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  • Surface plasmon-enhanced molecular fluorescence induced by gold nanostructures 査読

    Yu Teng, Kosei Ueno, Xu Shi, Daisuke Aoyo, Jianrong Qiu, Hiroaki Misawa

    ANNALEN DER PHYSIK   524 ( 11 )   733 - 740   2012年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    The authors report on surface plasmon-enhanced fluorescence of Eosin Y molecules induced by gold nanostructures. Al2O3 films deposited by atomic layer deposition with sub-nanometer resolution were used as the spacer layer to control the distance between molecules and the gold surface. As the thickness of the Al2O3 film increased, the fluorescence intensity first increased and then decreased. The highest enhancement factor is achieved with a 1 nm Al2O3 film. However, the trend for the fluorescence lifetime is the opposite. It first decreased and then increased. The changes in the fluorescence quantum yield were also calculated. The yield shows a similar trend to the fluorescence intensity. The competition between the surface plasmon-induced increase in the radiative decay rate and the gold-induced fluorescence quenching is responsible for the observed phenomenon. In addition, this competition strongly depends on the thickness of the spacer layer between Eosin Y molecules and the gold surface.

    DOI: 10.1002/andp.201200143

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  • Photoluminescence enhancement induced from silver nanoparticles in Tb3+-doped glass ceramics 査読

    Gang Bi, Li Wang, Wei Xiong, Kosi Ueno, Hiroaki Misawa, Jianrong Qiu

    CHINESE OPTICS LETTERS   10 ( 9 )   092401   2012年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHINESE LASER PRESS  

    We experimentally verify that surface plasmon (SP) enhances the photoluminescence (PL) of visible light from Tb3+-doped 60SiO(2)-20Al(2)O(3)-20CaF(2):0.3Tb(3+), 20Yb(3+) glass ceramics by using electron beam lithography to fabricate silver nanoparticles on the surface of the glass ceramics. Numerical calculation for the SP enhancement spectroscopy is achieved by using the finite-difference time-domain algorithm. A PL enhancement of Tb3+ by as much as 1.6 times is observed. The PL enhancement is mainly due to the coupling of excitation from F-7(6) to D-5(4) transition dipole of Tb3+ ion with SP mode induced from the silver nanoparticles.

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  • Improving Surface Plasmon Detection in Gold Nanostructures Using a Multi-Polarization Spectral Integration Method 査読

    Kuang-Li Lee, Min-Jian Chih, Xu Shi, Kosei Ueno, Hiroaki Misawa, Pei-Kuen Wei

    ADVANCED MATERIALS   24 ( 35 )   OP253 - OP259   2012年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

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  • Effect of Dipole Coupling on Near-IR LSPR and Coherent Phonon Vibration of Periodic Gold Pair Nanocuboids 査読

    Li Wang, Yoshiaki Nishijima, Kosei Ueno, Hiroaki Misawa, Naoto Tamai

    JOURNAL OF PHYSICAL CHEMISTRY C   116 ( 33 )   17838 - 17846   2012年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We examined the vibrational dynamics of periodic gold pair nanocuboids with various nanogaps and various pair-to-pair separations under 400 nm excitation by near-IR transient absorption spectroscopy. Multi-oscillation behavior of the coherent acoustic phonon vibration was observed for all the gold pair nanocuboid arrays. Two symmetric breathing modes were assigned to the displacement of edge-to-edge and its second harmonic, and the displacement of tip-to-tip of gold nanocuboids. We assigned the driving mechanisms of the edge-to-edge and the tip-to-tip modes to thermal expansion and hot-electron pressure, respectively, due to the different amplitudes and the phase mismatch between both modes. Moreover, Young's modulus of gold nanocuboids was estimated to be 97 GPa by using the measured vibrational periods of the edge mode. A little deviation from the bulk value (78 GPa) was interpreted in terms of an interaction of a gold nanocuboid with a substrate. In addition, the oscillation periods and damping constants of the phonon vibration were similar for all of the arrays, even though localized surface plasmon resonance (LSPR) bands were shifted due to near- and far-field dipole couplings. This phenomenon suggested that the phonon vibration was only influenced by the intrinsic properties of the nanomaterials. Furthermore, the oscillation amplitudes of the bleaching peaks exponentially decayed with the increase of the nanogap. We calculated the LSPR bands of gold pair nanocuboids with structural deformation by finite-difference time-domain simulation, and the estimated spectral shift was in good agreement with the experimental results.

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  • Fabrication of Nanoengineered Metallic Structures and Their Application to Nonlinear Photochemical Reactions 査読

    Kosei Ueno, Hiroaki Misawa

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   85 ( 8 )   843 - 853   2012年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    We used metallic nanoparticles exhibiting localized surface plasmon resonance and electromagnetic (EM) field enhancement effects induced by plasmon excitation for the photochemical reaction field; this approach makes it possible to increase the probability of an interaction between photons and the materials. EM field enhancement effects induced by gold nanostructures were elucidated using two-photon-induced photoluminescence from nanogap-spaced gold nanoparticles. The photoluminescence was promoted mainly in the surface regions of the gold nanoblocks adjacent to the nanogaps due to the EM field enhancement effect. To elucidate the near-field intensity distribution of the nanogap gold structures, we investigated the photopolymerization of a commercially available negative photoresist assisted by EM field enhancement in the nanogaps separating the gold nanoblocks. Photopolymerization rates were enhanced by several orders of magnitude in the gold nanoblock structures that contained nanogaps narrower than 10 nm. We propose two surface plasmon-assisted nanolithography techniques based on spatially selective photochemical reactions promoted by the EM field enhancement effect. The first method uses ultimate near-field lithography with a local near-field distribution induced in the nanogaps, and the second technique uses the scattering component of multipole plasmon resonance as an exposure mechanism. These lithographic techniques represent a type of application based on plasmon-enhanced chemical reactions.

    DOI: 10.1246/bcsj.20120123

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  • Far-Field Focusing of Spiral Plasmonic Lens 査読

    Junjie Miao, Yongsheng Wang, Chuanfei Guo, Ye Tian, Jianming Zhang, Qian Liu, Zhiping Zhou, Hiroaki Misawa

    PLASMONICS   7 ( 2 )   377 - 381   2012年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    In this paper, we study the nanoscale-focusing effect in the far field for a spiral plasmonic lens with a concentric annular groove by using finite-difference time domain simulation. The simulation result demonstrates that a left-hand spiral plasmonic lens can concentrate an incident right-hand circular polarization light into a focal spot at the exit surface. And this spot can be focused into far field due to constructive interference of the scattered light by the annular groove. The focal length and the focal depth can be adjusted by changing the groove radius and number of grooves within a certain range. These properties make it possible to probe the signal of spiral plasmonic lens in far field by using conventional optical devices.

    DOI: 10.1007/s11468-011-9318-0

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  • Quantitative Measurement of the Near-Field Enhancement of Nanostructures by Two-Photon Polymerization 査読

    Tobias Geldhauser, Andreas Kolloch, Naoki Murazawa, Kosei Ueno, Johannes Boneberg, Paul Leiderer, Elke Scheer, Hiroaki Misawa

    LANGMUIR   28 ( 24 )   9041 - 9046   2012年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    The quantitative determination of the strength of the near-field enhancement in and around nanostructures is essential for optimizing and using these structures for applications. We combine the Gaussian intensity distribution of a laser profile and two-photon-polymerization of SU-8 to a suitable tool for the quantitative experimental measurement of the near-field enhancement of a nanostructure. Our results give a feedback to the results obtained by finite-difference rime-domain (FDTD) simulations. The structures under investigation are gold nanotriangles on a glass substrate with 85 nm side length and a thickness of 40 nm. We compare the threshold fluence for polymerization for areas of the Gaussian intensity profile with and without the near-field enhancement of the nanostructures. The experimentally obtained value of the near-field intensity enhancement is 600 140, independent of the laser power, irradiation time, and spot size. The FDTD simulation shows a pointlike maximum of 2600 at the tip. In a more extended area with an approximate size close to the smallest polymerized structure of 25 nm in diameter, we find a value between 800 and 600. Using our novel approach, we determine the threshold fluence for polymerization of the commercially available photopolymerizable resin SU-8 by a femtosecond laser working at a wavelength of 795 nm and a repetition rate of 82 MHz to be 0.25 J/cm(2) almost independent of the irradiation time and the laser power used. This finding is important for future applications of the method because it enables one to use varying laser systems.

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  • Enhancement of a Two-Photon-Induced Reaction in Solution Using Light-Harvesting Gold Nanodimer Structures 査読

    Botao Wu, Kosei Ueno, Yukie Yokota, Kai Sun, Heping Zeng, Hiroaki Misawa

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   3 ( 11 )   1443 - 1447   2012年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We performed a quantitative analysis of plasmon-assisted two-photon photochromic reactions on light-harvesting gold nanodimer structures. Our strategy for the quantitative analysis of two-photon-induced photochemical reactions on gold nanostructures is using not only a confined photochemical reaction chamber but also a solution system. The strong intensification of near-field light at the nanogap positions on gold nanodimer pairs promoted two-photon absorption by a closed-form diarylethene derivative, resulting in highly efficient photochromic conversion to the open-form structure.

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  • Near-Infrared Plasmon-Assisted Water Oxidation 査読

    Yoshiaki Nishijima, Kosei Ueno, Yuki Kotake, Kei Murakoshi, Haruo Inoue, Hiroaki Misawa

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   3 ( 10 )   1248 - 1252   2012年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We report the stoichiometric evolution of oxygen via water oxidation by irradiating a plasmon-enhanced photocurrent generation system with near-infrared light (lambda: 1000 am), in which gold nanostructures were arrayed on the surface of TiO2 electrode. It is considered that multiple electron holes generated by plasmon-induced charge excitation led to the effective recovery of water oxidation after the electron transfer from gold to TiO2. The proposed system containing a gold nanostructured TiO2 electrode may be a promising artificial photosynthetic system using near-infrared light.

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  • Effect of the distance between adherent mesenchymal stem cell and the focus of irradiation of femtosecond laser on cell replication capacity 査読

    Jun Sakai, Daniel Roldan, Kosei Ueno, Hiroaki Misawa, Yoichiroh Hosokawa, Takanori Iino, Shigeyuki Wakitani, Mutsumi Takagi

    CYTOTECHNOLOGY   64 ( 3 )   323 - 329   2012年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    The effect of femtosecond laser irradiation on adherent mesenchymal stem cell was investigated with the aim to develop a novel noninvasive cell purification system. A single mesenchymal stem cell was irradiated with a femtosecond laser on the center of the cell using several energy values and the cell lost its replication capacity with one time irradiation with an energy of 2.0 mu J. Besides at a neighbor point in the major axis, when irradiated in the minor axis at a distance shorter than 10 mu m, the cell stopped its replication capacity. The accumulation effect of cell damage caused by multiple laser shots at a neighbor point in the minor axis was correlated with the critical distance at which the cell lost its replication capacity. Finally, a novel equation of laser cell damage as a function of laser pulse energy and laser shot number is proposed.

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  • Fabrication of periodical structure and shape-induced modulating spectroscopy of Au nanoparticles 査読

    Gang Bi, Wei Xiong, Li Wang, Kosei Ueno, Hiroaki Misawa, Jian-rong Qiu

    OPTICS COMMUNICATIONS   285 ( 9 )   2472 - 2477   2012年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    This paper presents optical property of the periodical bowties structure of Au nanoparticles on glass substrate fabricated by high-resolution electron beam lithography. Numerical calculation is used to examine the shape-induced surface plasmon enhancement and extinction spectroscopy by using Finite-Difference Time Domain algorithm and Lorentz model of surface plasmon. The calculated extinction spectra of the periodical nanoparticles are consistent with the experimental results. The influence of the geometrical shape on the spectral properties of bowtie nanoparticles is discussed. This investigation may help one to design plasmonic sub-wavelength devices with desired spectral properties. (C) 2012 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.optcom.2012.01.032

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  • Photonic Crystal Nanolaser Biosensors 査読

    Kita, Shota, Otsuka, Shota, Hachuda, Shoji, Endo, Tatsuro, Imai, Yasunori, Nishijima, Yoshiaki, Misawa, Hiroaki, Baba, Toshihiko

    IEICE TRANSACTIONS ON ELECTRONICS   E95C ( 2 )   188 - 198   2012年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

    High-performance and low-cost sensors are critical devices for high-throughput analyses of bio-samples in medical diagnoses and life sciences. In this paper, we demonstrate photonic crystal nanolaser sensor, which detects the adsorption of biomolecules from the lasing wavelength shift. It is a promising device, which balances a high sensitivity, high resolution, small size, easy integration, simple setup and low cost. In particular with a nanoslot structure, it achieves a super-sensitivity in protein sensing whose detection limit is three orders of magnitude lower than that of standard surface-plasmon-resonance sensors. Our investigations indicate that the nanoslot acts as a protein condenser powered by the optical gradient force, which arises from the strong localization of laser mode in the nanoslot.

    DOI: 10.1587/transele.E95.C.188

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  • In situ investigation of the shrinkage of photopolymerized micro/nanostructures: the effect of the drying process 査読

    Quan Sun, Kosei Ueno, Hiroaki Misawa

    OPTICS LETTERS   37 ( 4 )   710 - 712   2012年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    We report on experimental study of the shrinkage of photopolymerized micro/nanostructures fabricated by femto-second direct laser writing in organic-inorganic resists. Blueshift of the stop-band positions of fabricated photonic crystals during the drying process, which follows the development and rinsing stages, indicates that the drying process plays an important role in the formation of the shrinkage. It is further confirmed that the shrinkage almost completely occurs during the drying process by in situ optical monitoring the structures. These findings will help to better understand, control, and even positively utilize the shrinkage in the applications of the photopolymerization-based direct laser writing technique. (C) 2012 Optical Society of America

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  • Surface plasmon-assisted nanolithography with nanometric accuracy 査読

    K. Ueno, H. Misawa

    LASER APPLICATIONS IN MICROELECTRONIC AND OPTOELECTRONIC MANUFACTURING (LAMOM) XVII   8243   2012年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    Advanced lithography systems, such as ArF immersion lithography, have achieved a 32 nm node(1,2) and are already used in electronic device development. However, the advanced lithography systems are not suitable for fabricating nanostructures, such as rectangular cuboids, triangular prisms, chains, and nanogaps. These nanostructures are being used for various applications that include plasmonic solar cells(3-5) and photonic crystal lasers. (6, 7) In this proceeding, we report an innovative lithography system appropriate for fabricating such nano-patterns with nanometric accuracy based on plasmon-assisted photolithography. The key technology is the two-photon photochemical reaction of a photoresist induced by plasmonic near-field light and propagating light in a photoresist film. This propagating light is a radiation mode from a higher order of localized surface plasmon resonances scattered by metallic nanostructures. The system does not induce nano-pattern deformation at the time of mask release. This system presents a simple alternative for producing nano-patterns instead of using nanoimprinting.

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  • Real-time imaging of acoustic rectification 査読

    S. Danworaphong, T. A. Kelf, O. Matsuda, M. Tomoda, Y. Tanaka, N. Nishiguchi, O. B. Wright, Y. Nishijima, K. Ueno, S. Juodkazis, H. Misawa

    APPLIED PHYSICS LETTERS   99 ( 20 )   201910   2011年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    We image gigahertz surface acoustic waves normally incident on a microscopic linear array of triangular holes-a generic "acoustic diode" geometry-with a real-time ultrafast optical technique. Spatiotemporal Fourier transforms reveal wave diffraction orders in k-space. Squared amplitude reflection and transmission coefficients for incidence on both sides of the array are evaluated and compared with numerical simulations. We thereby directly demonstrate acoustic rectification with an asymmetric structure. (C) 2011 American Institute of Physics. [doi:10.1063/1.3662930]

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  • Plasmon-induced local photocurrent changes in GaAs photovoltaic cells modified with gold nanospheres: A near-field imaging study 査読

    Yosuke Harada, Kohei Imura, Hiromi Okamoto, Yoshiaki Nishijima, Kosei Ueno, Hiroaki Misawa

    JOURNAL OF APPLIED PHYSICS   110 ( 10 )   104306   2011年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    Modification of photovoltaic devices with metallic nanoparticles is expected to be one of the key methods for development of high performance devices as a future energy source. To clarify the mechanism of photocurrent changes induced by surface plasmon resonances of metal nanoparticles, we measured near-field photocurrent excitation images for a GaAs photodiode modified with gold nanospheres (diameter 100 nm) with a spatial resolution higher than 100 nm. The relationship between the photovoltaic efficiency and the plasmons of the gold nanospheres was investigated through the measurements of incident wavelength and polarization dependence of the near-field photocurrent images. Isolated nanospheres deposited on the GaAs active surface caused local photocurrent suppressions at the plasmon resonance wavelengths. In the case of assemblies (dimers and trimers) of the spheres, a remarkable decrease of photocurrent at the gap site between the spheres was observed. From the results, it turned out that the enhanced optical fields created via the plasmons on the metal nanostructures do not improve the photovoltaic efficiency and that forward scattering of photons by the gold nanoparticles is considered to be more important than the enhanced field effect at the particles for the GaAs photovoltaic device studied. (C) 2011 American Institute of Physics. [doi:10.1063/1.3662114]

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  • A simultaneous space sampling method for DNA fraction collection using a comb structure in microfluidic devices 査読

    Zheyu Li, Kai Sun, Misato Sunayama, Ryoko Araki, Kosei Ueno, Masumi Abe, Hiroaki Misawa

    ELECTROPHORESIS   32 ( 23 )   3392 - 3398   2011年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-BLACKWELL  

    Fraction collection of selected components from a complex mixture plays a critical role in biomedical research, environmental analysis, and biotechnology. Here, we introduce a novel electrophoretic chip device based on a signal processing theorem that allows simultaneous space sampling for fractionation of ssDNA target fragments. Ten parallel extraction channels, which covered 1.5-mm-long sampling ranges, were used to facilitate the capturing of fast-moving fragments. Furthermore, the space sampling extraction made it possible to acquire pure collection, even from partly overlapping fragments that had been insufficiently separated after a short electrophoretic run. Fragments of 180, 181, and 182 bases were simultaneously collected, and then the recovered DNA was PCR amplified and assessed by CE analysis. The 181-base target was shown to be isolated in a 70-mm-long separation length within 10?min, in contrast to the &gt;50?min required for the 300-mm-long separation channel in our previous study. This method provides effective combination of time and space, which is a breakthrough in the traditional concept of fraction collection on a chip.

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  • Spectral properties of nanoengineered Ag/Au bilayer rods fabricated by electron beam lithography 査読

    Li Wang, Wei Xiong, Yoshiaki Nishijima, Yukie Yokota, Kosei Ueno, Hiroaki Misawa, Jianrong Qiu, Gang Bi

    APPLIED OPTICS   50 ( 28 )   5600 - 5605   2011年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    Ag/Au bimetallic nanoparticles possess the combinatory advantages of Au and Ag nanoparticles and can also be utilized to tune the properties of localized surface plasmon resonance. Ag/Au bilayer nanorods were prepared by electron beam lithography, and their spectral properties were investigated. Compared with Ag monolayer nanorods, Ag/Au bilayer nanorods show broader localized surface plasmon resonance bands, and the longitudinal mode and transverse mode localized surface plasmon bands show blueshift and redshift, respectively. The maximum near-field intensity of the longitudinal mode of the Ag/Au nanorod is less than half that of the Ag/Au nanorod without gold layer. Shape-induced modification of Ag/Au bilayer nanorods on their spectral properties was also discussed. (C) 2011 Optical Society of America

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  • Spectral Properties of Nanoengineered Ag/Au Bilayer Rods Fabricated by Electron Beam Lithography 査読

    L. Wang, W. Xiong, Y. Nishijima, Y. Yokota, K. Ueno, H. Misawa, J. R. Qiu, G. Bi

    Appl. Opt.   50 ( 28 )   5600   2011年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Fabrication of a Au/Si nanocomposite structure by nanosecond pulsed laser irradiation 査読

    Yutaka Yoshida, Seiichi Watanabe, Yoshiaki Nishijima, Kosei Ueno, Hiroaki Misawa, Takahiko Kato

    NANOTECHNOLOGY   22 ( 37 )   375607-1-7   2011年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    A gold/silicon nanocomposite structure (NCS) was formed on a Si(100) surface by nanosecond pulsed laser irradiation. The Au/Si NCS contained both Au nanoparticles (NPs) and Au-Si alloy layers. We report that the use of laser irradiation to form Au NPs comprises two competing processes: a top-down effect involving decomposition into smaller NPs and a bottom-up effect involving self-assembly or self-organization into larger NPs. The formation of the periodic structure involved self-organization, i.e., the bottom-up effect, and was observed in situ using a pulsed-laser-equipped high-voltage electron microscope. The NCS formed by laser irradiation can be controlled by adjusting the laser energy density and the number of laser pulses.

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  • Femtosecond and picosecond near-field ablation of gold nanotriangles: nanostructuring and nanomelting 査読

    A. Kolloch, T. Geldhauser, K. Ueno, H. Misawa, J. Boneberg, A. Plech, P. Leiderer

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   104 ( 3 )   793 - 799   2011年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    We report on recent insights into the interaction between ultra-fast laser pulses and plasmonic nanoparticles. We discuss femtosecond near-field ablation as a simple but versatile tool for the nanoscale modification of surfaces and the high-resolution measurement of a nanostructure's near field. Two model systems are presented, illustrating the complexity of near-field distributions. Furthermore, finite difference time domain calculations in combination with absorption spectra provide a deeper insight into the factors influencing the near-field distribution. For the first time, an almost perfect agreement between the measured ablation pattern and experiment has been reached for gold triangles with a side length around 500 nm. Additionally, the results from picosecond laser irradiated plasmonic structures display a new regime of nanoscale laser material processing. We present first results showing nanometre confined melting induced by laser pulses.

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  • Spatial polarization sensitivity of single Au bowtie nanostructures 査読

    E. Wu, Yingzhi Chi, Botao Wu, Kangwei Xia, Yukie Yokota, Kosei Ueno, Hiroaki Misawa, Heping Zeng

    JOURNAL OF LUMINESCENCE   131 ( 9 )   1971 - 1974   2011年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Metallic bowtie nanostructures as plasmonic nanoantennas can create highly enhanced local fields when resonating with the incident light. With Au bowtie nanostructures fabricated by lithography method, we experimentally observed that the photoluminescence (PL) spatial profile from a single Au bowtie nanoantenna was strongly dependent on the excitation light polarization. While varying the incident light polarization, the spatial distribution of the PL intensity in the nanogap of an Au bowtie changed as predicted by the simulation results on the electromagnetic field enhancement distribution. The polarization feature of the PL intensity relative to the polarization direction of incident excitation light was also discussed. The study may find application in the design of polarization sensitive plasmonic sensors. (C) 2011 Elsevier B.V. All rights reserved.

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  • Modifying Plasmonic Spectral Properties of Engineered Silver Nanoblocks by Using Titanium Coating 査読

    Li Wang, Wei Xiong, Yoshiaki Nishijima, Yukie Yokota, Kosei Ueno, Hiroaki Misawa, Gang Bi, Jianrong Qiu

    IEEE PHOTONICS TECHNOLOGY LETTERS   23 ( 17 )   1216 - 1218   2011年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    Plasmonic spectral properties of silver nanoblocks fabricated by electron beam lithography are investigated. The extinction spectra of silver nanoblocks showed a red shift, broadening, and damping with the passage of storage time. In contrast, silver nanoblocks with titanium coating on the top did not show apparent spectral change even after storage for two months. Morphological change of the silver nanoblocks was characterized by scanning electron microscope. The present work clearly demonstrates that coating titanium on the top of the silver nanostructures is an effective way to prevent them from chemical corrosion and stabilize their plasmonic spectral properties.

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  • Super-sensitivity in label-free protein sensing using a nanoslot nanolaser 査読

    Kita, Shota, Hachuda, Shoji, Otsuka, Shota, Endo, Tatsuro, Imai, Yasunori, Nishijima, Yoshiaki, Misawa, Hiroaki, Baba, Toshihiko

    OPTICS EXPRESS   19 ( 18 )   17683 - 17690   2011年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    Microphotonic sensors have been actively studied with increasing demands for label-free biosensing in medical diagnoses and life sciences. For high-throughput and low-cost sensing, a high sensitivity is crucial for eliminating the pre-concentration process, while a simple setup of sensors is also desirable. This paper demonstrates a super-sensitivity for protein, which satisfies these requirements. The key device is a photonic crystal nanolaser, in particular with a nanoslot. Even using a simple setup, the nanolaser achieves an extraordinary-low detection limit for BSA protein, i.e. 255 fM on an average, which cannot be explained by its bulk index sensitivity. The specific adsorption of the protein is observed only around the nanoslot with strong laser intensity. This suggests that the super-sensitivity arises from the effective trapping of protein in the nanoslot. (C) 2011 Optical Society of America

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  • Homogeneous nano-patterning using plasmon-assisted photolithography 査読

    Kosei Ueno, Satoaki Takabatake, Ko Onishi, Hiroko Itoh, Yoshiaki Nishijima, Hiroaki Misawa

    APPLIED PHYSICS LETTERS   99 ( 1 )   011107   2011年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    We report an innovative lithography system appropriate for fabricating sharp-edged nanodot patterns with nanoscale accuracy using plasmon-assisted photolithography. The key technology is two-photon photochemical reactions of a photoresist induced by plasmonic near-field light and the scattering component of the light in a photoresist film. The scattering component of the light is a radiation mode from higher order localized surface plasmon resonances scattered by metallic nanostructures. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3606505]

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  • Preface 査読

    Hiroaki Misawa

    Journal of Photochemistry and Photobiology A: Chemistry   221 ( 2-3 )   129   2011年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.jphotochem.2011.06.004

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  • Photochemical reaction fields with strong coupling between a photon and a molecule 査読

    Kosei Ueno, Hiroaki Misawa

    Journal of Photochemistry and Photobiology A: Chemistry   221 ( 2-3 )   130 - 137   2011年6月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    To achieve a future low-carbon society, the effective utilization of photons is essential for the development of technologies based on photochemistry, such as photocatalysis and dye-sensitized solar cells, which have the potential to produce clean energy as well as preserve the environment. Here, we propose that gold nanostructures exhibiting localized surface plasmon (LSP) resonance are promising sites for photochemical reaction fields that increase the interaction between a photon and molecule. These interactions are based on electromagnetic field enhancement effects that are induced by LSP excitations and their localization. In this review, recent studies on the strong coupling field between a photon and molecule for photochemical reactions are discussed. As an outstanding example, this concept was applied to the plasmonic, photoelectric conversion of visible to near-infrared wavelengths using electrodes in which gold nanoblocks were elaborately arrayed on the surface of a single TiO2 crystal. The most important characteristic of this photoelectric conversion is that the photocurrent was stable for more than 200 h without adding the donors, which suggests the possibility that water molecules can act as donors that provide electrons to the d-band holes assisted by the LSP excitation. Therefore, this system has the potential for use in artificial photosynthesis systems with irradiation from near-infrared light. © 2011 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jphotochem.2011.04.014

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  • Plasmon coupling and coherent acoustic phonon dynamics of periodic gold pair nanocuboids by near-IR transient absorption spectroscopy 査読

    Li Wang, Yoshiaki Nishijima, Kosei Ueno, Hiroaki Misawa, Naoto Tamai

    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY   221 ( 2-3 )   164 - 168   2011年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE SA  

    Gold pair nanocuboids (size: 150 nm x 150 nm x 20 nm) with different nanogaps ranging from 0 to 10.6 nm were prepared by the electron-beam lithography. Effect of plasmon coupling on coherent acoustic phonon dynamics of gold pair nanocuboids was examined as a function of nanogaps by near-IR transient absorption spectroscopy at 400-nm excitation. The similar oscillation periods of coherent acoustic phonon vibration (88 +/- 1 ps) were observed for all the gold pair nanocubiods irrespective of the nanogaps, which was analyzed by the oscillation of bleaching peaks of SPR bands and the transient absorption dynamics. The coherent acoustic phonon vibration of gold nanocuboids was only influenced by the nanostructure itself, even though SPR band was much influenced due to the dipole coupling between the adjacent Au nanocuboids. In addition, it was revealed that the electron-phonon coupling (similar to 0.7 ps) was followed by the initial size change of gold nanocuboid with the time scale that was a little slower (similar to 1.7 ps) than the electron-phonon coupling. (C) 2011 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jphotochem.2011.02.023

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  • Protein crystallization induced by strong photons-molecules coupling fields photochemical reaction 査読

    Susumu Haruta, Hiroaki Misawa, Kosei Ueno, Yukie Yokota, Hiroki Uehara, Hiroshi Hiratsuka, Hiroaki Horiuchi, Tetsuo Okutsu

    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY   221 ( 2-3 )   268 - 272   2011年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE SA  

    Photochemically induced protein crystallization byprotein&apos;s multiphoton excitation based on enhanced field of localized surface plasmon resonance (LSPR) of gold nanostructures was investigated. As strong photons-molecules coupling fields, gold nanostructures composed of nanoblocks and gold nanocolloid were used. With gold nanostructures, we could observe enzyme activity decrease by light irradiation that protein does not absorb. Surface observation of gold nanostructure by DFM (non-contact dynamic force microscope) shows that proteins were aggregated at around the nanoblock due to photochemical reaction by enhanced field. Crystallization probability depends on the excitation photon fluence, which indicates 3 photons absorption process occurred. (C) 2011 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jphotochem.2011.03.012

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  • Photochemical reaction fields with strong coupling between a photon and a molecule 査読

    Kosei Ueno, Hiroaki Misawa

    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY   221 ( 2-3 )   130 - 137   2011年6月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE SA  

    To achieve a future low-carbon society, the effective utilization of photons is essential for the development of technologies based on photochemistry, such as photocatalysis and dye-sensitized solar cells, which have the potential to produce clean energy as well as preserve the environment. Here, we propose that gold nanostructures exhibiting localized surface plasmon (LSP) resonance are promising sites for photochemical reaction fields that increase the interaction between a photon and molecule. These interactions are based on electromagnetic field enhancement effects that are induced by LSP excitations and their localization. In this review, recent studies on the strong coupling field between a photon and molecule for photochemical reactions are discussed. As an outstanding example, this concept was applied to the plasmonic, photoelectric conversion of visible to near-infrared wavelengths using electrodes in which gold nanoblocks were elaborately arrayed on the surface of a single TiO2 crystal. The most important characteristic of this photoelectric conversion is that the photocurrent was stable for more than 200 h without adding the donors, which suggests the possibility that water molecules can act as donors that provide electrons to the d-band holes assisted by the LSP excitation. Therefore, this system has the potential for use in artificial photosynthesis systems with irradiation from near-infrared light. (C) 2011 Elsevier B.V. All rights reserved.

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  • Visualization of Near-Field Enhancements of Gold Triangles by Nonlinear Photopolymerization 査読

    Tobias Geldhauser, Shintarou Ikegaya, Andreas Kolloch, Naoki Murazawa, Kosei Ueno, Johannes Boneberg, Paul Leiderer, Elke Scheer, Hiroaki Misawa

    PLASMONICS   6 ( 2 )   207 - 212   2011年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    We report in this paper the near-field distribution in the case of gold triangle arrays by means of two-photon polymerization for a dipole and a quadrupole plasmon mode. In order to link the finite difference in the time domain (FDTD) simulations of the triangle array and the experimental results, extinction spectra for both cases in air and SU-8 environments are shown. In case of the 40-nm thick gold triangles with 85-nm side-length, we show that the calculated and experimentally obtained near-field for the excited dipole mode has the same distribution along the polarization of the exciting laser beam. In case of bigger triangles of 540-nm side-length a quadrupole mode is excited, which leads to a rotation of the near-field distribution by 90A degrees referred to the polarization of the beam. This effect is also shown in the FDTD simulations.

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  • Spectral properties and mechanism of instability of nanoengineered silver blocks 査読

    Li Wang, Wei Xiong, Yoshiaki Nishijima, Yukie Yokota, Kosei Ueno, Hiroaki Misawa, Gang Bi, Jian-rong Qiu

    OPTICS EXPRESS   19 ( 11 )   10640 - 10646   2011年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    The instability of silver nanoblocks under atmospheric conditions is investigated. The localized surface plasmon resonance band of the silver nanoblocks shows a red shift, broadening, and damping with increasing storage time under atmospheric conditions. The change in spectral properties of silver nanoblocks is considered to be due to sulfidation of silver and structural breakage of silver nanoblock based on scanning electron microscope observation and numerical simulation. The effect of aspect ratio of silver nanoblocks on the change in spectral properties of the nanoengineered silver blocks is also discussed. (C) 2011 Optical Society of America

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  • S. Gao, K. Ueno, and H. Misawa 査読

    Plasmonic Antenna, Effects on, Photochemical Reactions

    Accounts of chemical research   44 ( 4 )   251 - 260   2011年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Direct imaging of nanogap-mode plasmon-resonant fields 査読

    Yoshito Tanaka, Hiroyasu Ishiguro, Hideki Fujiwara, Yukie Yokota, Kosei Ueno, Hiroaki Misawa, Keiji Sasaki

    OPTICS EXPRESS   19 ( 8 )   7726 - 7733   2011年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    We perform direct local-field imaging of a plasmon-resonant gold nanoparticle pair separated by a gap of several nanometers using a scattering-type near-field optical microscope with a sharp silicon tip of atomic force microscope. The sharp tip allows the access for the nanogap and the high spatial resolution. Our results provide experimental evidence that the nanogap structure produces an optical spot with the size of a single nanometer (&lt; 10 nm). This is not only of fundamental importance in the field of nanophotonics, but also provide significant information for the development of plasmonic devices with the nanogap structures. (C) 2011 Optical Society of America

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  • Anomalous light transmission from plasmonic-capped nanoapertures 査読

    Kohei Imura, Kosei Ueno, Hiroaki Misawa, Hiromi Okamoto

    Nano Letters   11 ( 3 )   960 - 965   2011年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We report an anomalous light transmission phenomenon for a nanoaperture on an opaque screen when the aperture is covered with an opaque cap. In conventional optics, light transmission must decrease when the aperture is capped. However, we found that light transmission is enhanced when the nanodisk is in close proximity to the aperture at a wavelength close to the plasmon resonance. This effect even occurs when the disk is larger than the aperture. © 2011 American Chemical Society.

    DOI: 10.1021/nl103408h

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  • Anomalous Light Transmission from Plasmonic-Capped Nanoapertures 査読

    Kohei Imura, Kosei Ueno, Hiroaki Misawa, Hiromi Okamoto

    NANO LETTERS   11 ( 3 )   960 - 965   2011年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We report an anomalous light transmission phenomenon for a nanoaperture on an opaque screen when the aperture is covered with an opaque cap. In conventional optics, light transmission must decrease when the aperture is capped. However, we found that light transmission is enhanced when the nanodisk is in close proximity to the aperture at a wavelength dose to the plasmon resonance. This effect even occurs when the disk is larger than the aperture.

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  • On-chip fraction collection for multiple selected ssDNA fragments using isolated extraction channels 査読

    Zheyu Li, Kai Sun, Misato Sunayama, Yasutaka Matsuo, Vygantas Mizeikis, Ryoko Araki, Kosei Ueno, Masumi Abe, Hiroaki Misawa

    JOURNAL OF CHROMATOGRAPHY A   1218 ( 7 )   997 - 1003   2011年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    High efficiency and high-purity fraction collection is highly sought in analysis of fragments-of-interest from selective polymerase chain reaction (PCR) products generated by High Coverage Gene Expression Profiling (HiCEP) methods. Here we demonstrate a new electrophoretic chip device enabling automatic high-efficient fractionation of multiple ssDNA target fragments during a run of separation. We used thoroughly isolated extraction channels for each selected target to reduce the risk of cross-contamination between targets due to cross-talk of extraction channels. Fragments of 35, 108 and 138 b, were successfully isolated, then the recovery was PCR-amplified and assessed by capillary electrophoresis (CE) analysis. Total impurity level of the targets due to unwanted fragments of 0.7%, 2% and 6% respectively, was estimated. Difficulties in collecting multiple target factions are due to band diffusion and DNA adsorption to the walls for the fragments in the separation channel, which is generated by transferring the DNA target fraction from the extraction section to the target reservoir. Therefore, we have carefully measured band broadening and analyzed its influence on the separation resolution due to the delay. (C) 2010 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.chroma.2010.12.089

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  • Highly Controlled Surface-Enhanced Raman Scattering Chips Using Nanoengineered Gold Blocks 査読

    Yukie Yokota, Kosei Ueno, Hiroaki Misawa

    SMALL   7 ( 2 )   252 - 258   2011年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    Well defined gold nanostructures of various sizes are fabricated on glass substrates using high-resolution electron-beam lithography/lift-off techniques and detailed surface-enhanced Raman scattering (SERS) properties of crystal violet molecules are studied in order to elucidate electromagnetic (EM) field enhancement effects on the fabricated structures. SERS measurements are performed with high reproducibility using in situ Raman microspectroscopy in aqueous solution. An analysis based on EM theory is performed using field-enhancement factors obtained from finite-difference time-domain (FDTD) simulations and the analysis reproduces experimental results very well. It is noteworthy, furthermore, that the proposed analytic method of EM effects on SERS allows the estimate of the ideal local temperature of gold nanostructures by canceling out the difference in EM field factors at Stokes and anti-Stokes Raman scattering wavelengths. Thus, these experimental results demonstrate that quantitative analysis based on EM theory can be obtained using highly controlled gold nanostructures for SERS measurements with high reproducibility, a result that is promising for the construction of a SERS analysis chip. Although no SERS chip reported so far has been usable for quantitative analysis, this study opens the door for construction of a quantitative SERS chip.

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  • Hybrid-State Dynamics of Gold Nanorods/Dye J-Aggregates under Strong Coupling 査読

    Ya-Wei Hao, Hai-Yu Wang, Ying Jiang, Qi-Dai Chen, Kosei Ueno, Wen-Quan Wang, Hiroaki Misawa, Hong-Bo Sun

    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION   50 ( 34 )   7824 - 7828   2011年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-BLACKWELL  

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  • Plasmon-Enhanced Water Oxidation on Gold Nanostructured TiO2 Single Crystal Substrates 査読

    Misawa Hiroaki, Nishijima Yoshiaki, Ueno Kosei, Murakoshi Kei, Inoue Haruo

    Meeting Abstracts   ( 36 )   1295   2011年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Trapping of protein in nanoslot nanolaser sensor 査読

    Shota Kita, Shota Otsuka, Tatsuro Endo, Yoshiaki Nishijima, Hiroaki Misawa, Toshihiko Baba

    15th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2011, MicroTAS 2011   2 ( 3 )   1275-1277   2011年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Controlling plasmonic spectral properties of engineered silver nanorods by using titanium coating 査読

    Wang Li, Xiong Wei, Nishijima Y, Yokota Y, Ueno K, Misawa H, Bi G, Qiu JR

    IEEE Photon. Technol. Lett.   2011年

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  • Polarization Dependence for Enhancement of Near-Infrared Fluorescence Intensity by Local Surface Plasmon Resonance from Arranged Gold Nanoblocks 査読

    Fuyuki Ito, Ryuichi Ohta, Yukie Yokota, Kosei Ueno, Hiroaki Misawa, Toshihiko Nagamura

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   538   265 - 271   2011年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:TAYLOR & FRANCIS LTD  

    The polarization dependence of excitation light for fluorescence enhancement of near-infrared dyes immobilized in hydrophobic DNA thin film on glass substrates with regularly arranged Au nanoblocks was investigated. The enhancement factor for S-polarized excitation was about 1.2 to 1.5 times as large as that for P-polarized excitation. P-polarized light contributed to the excitation of plasmon band both of horizontal and vertical direction of Au nanoblocks. The vertical direction corresponds to the short axis for height direction which has the absorption in visible region did not contribute the excitation of IR780. When the absorption band of Au array and the fluorescence band of IR780 were overlapped, the fluorescence enhancement did not depend on the polarization of excitation light. It is suggested that the fluorescence quenching originates from the energy transfer from the excited state of IR780 to Au nanoblocks or the increased deactivation of excited dye molecules induced by resonance with Au nanoblocks.

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  • Essential nanogap effects on surface-enhanced Raman scattering signals from closely spaced gold nanoparticles 査読

    Yukie Yokota, Kosei Ueno, Hiroaki Misawa

    CHEMICAL COMMUNICATIONS   47 ( 12 )   3505 - 3507   2011年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    We have demonstrated the essential nanogap effects on surface-enhanced Raman scattering (SERS) signals obtained from two diagonally aligned gold nanoparticles with several nanometre separations, which were precisely fabricated on a glass substrate. This is the first proof of principle for extracting the light localization effects on SERS due to the formation of nanogaps from experimentally observed SERS signals.

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  • Near-infrared Fluorescence Enhancement by Regularly Arranged Gold Nanoblocks 査読

    Fuyuki Ito, Ryuichi Ohta, Yukie Yokota, Kosei Ueno, Hiroaki Misawa, Toshihiko Nagamura

    CHEMISTRY LETTERS   39 ( 11 )   1218 - 1219   2010年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    Fluorescence intensity of near Infrared dyes immobilized in hydrophobic DNA thin film spin-coated on glass substrates with regularly arranged gold (Au) nanoblocks was about 2 5 times larger than that without Au nanoblocks, strongly suggesting the fluorescence intensity was enhanced by increased electric field intensity of excitation light due to local plasmon resonance of Au nanoblocks

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  • Pulse duration dependent nonlinear propagation of a focused femtosecond laser pulse in fused silica 査読

    Quan Sun, Hidenori Asahi, Yoshiaki Nishijima, Naoki Murazawa, Kosei Ueno, Hiroaki Misawa

    OPTICS EXPRESS   18 ( 24 )   24495 - 24503   2010年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    The nonlinear propagation of a single focused femtosecond laser pulse in fused silica has been investigated both experimentally and by numerical simulations. In particular, the filamentation behavior was systematically studied by varying pulse duration. At low pulse energy, the peak plasma density inside the filament first increases to a maximum value with increasing pulse duration and then begins to decrease. At relatively high pulse energy, denser plasma can be induced around the geometrical focus with a certain longer pulse duration, where the peak power is already below the self-focusing critical power and no filament is formed. This pulse duration dependent behavior can be explained by different ionization mechanisms. (c) 2010 Optical Society of America

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  • Flexible Nanowiring of Metal on Nonplanar Substrates by Femtosecond-Laser-Induced Electroless Plating 査読

    Bin-Bin Xu, Hong Xia, Li-Gang Niu, Yong-Lai Zhang, Kai Sun, Qi-Dai Chen, Ying Xu, Zhi-Qiu Lv, Zhi-Hong Li, Hiroaki Misawa, Hong-Bo Sun

    SMALL   6 ( 16 )   1762 - 1766   2010年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

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  • Plasmon-Assisted Photocurrent Generation from Visible to Near-Infrared Wavelength Using a Au-Nanorods/TiO2 Electrode 査読

    Yoshiaki Nishijima, Kosei Ueno, Yukie Yokota, Kei Murakoshi, Hiroaki Misawa

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   1 ( 13 )   2031 - 2036   2010年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Nanoparticles of noble metals exhibit localized surface plasmons (LSPs) associated with the enhancement of an electromagnetic field due to its localization in nanometric domains at the surface of nanoparticles. We demonstrate the plasmonic photoelectric conversion from visible to near-infrared wavelength without deteriorating photoelectric conversion by using electrodes in which gold nanorods are elaborately arrayed on the surface of a TiO2 single crystal.

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  • Fabrication of Frequency-Selective Surface Structures by Femtosecond Laser Ablation of Gold Films 査読

    Vygantas Mizeikis, Saulius Juodkazis, Kai Sun, Hiroaki Misawa

    JOURNAL OF LASER MICRO NANOENGINEERING   5 ( 2 )   115 - 120   2010年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN LASER PROCESSING SOC  

    Simple frequency-selective surface (FSS) structures consisting of two-dimensional (2D) triangular lattices of circular apertures with an aperture diameter of about 0.6-0.8 mu m and a lattice period of 1.0 and 2.0 mu m were fabricated by femtosecond laser ablation of thin gold films deposited on glass substrates. The fabricated samples were found to exhibit spectral transmission bands at infrared wavelengths, and significant surface plasmonic (SP) local enhancement of the near-field near the metal's surface according to experimental transmission measurements and theoretical simulation by Finite-Difference Time-Domain (FDTD) technique. These results indicate versatility of femtosecond laser ablation technique for rapid prototyping of metallic FSS and plasmonic structures. DOI:10.2961/jlmn.2010.02.0003

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  • Nano-Patterning of a TiO2-Organic Hybrid Material Assisted by a Localized Surface Plasmon 査読

    Hiroyo Segawa, Kosei Ueno, Yukie Yokota, Hiroaki Misawa, Tetsuji Yano, Shuichi Shibata

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY   93 ( 6 )   1634 - 1638   2010年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-BLACKWELL  

    Nanopatterns of a TiO2-organic hybrid material have been fabricated with the use of a localized surface plasmon (LSP). The TiO2-organic hybrid material was prepared by the sol-gel method and was coated on a glass substrate with gold nanoblocks. After the hybrid films were irradiated with a femtosecond laser, the unreacted parts were removed, leaving the TiO2-organic hybrid materials around the nanoblocks. In the nanopatterns of the TiO2-organic hybrid materials, the pi - pi* transition absorption band of the chelate compound formed between Ti-alkoxide and beta-diketone was excited by the two-photon absorption induced by the LSP of gold nanoblocks, and the chelate compound was decomposed and dissolved in alcohol. It was confirmed that the hybrid material changed to anatase upon sintering above 450 degrees C.

    DOI: 10.1111/j.1551-2916.2010.03645.x

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  • Influence of laser microfabrication on silicon electrochemical behavior in HF solution 査読

    Kestutis Juodkazis, Jurga Juodkazyte, Putinas Kalinauskas, Titas Gertus, Edgaras Jelmakas, Hiroaki Misawa, Saulius Juodkazis

    JOURNAL OF SOLID STATE ELECTROCHEMISTRY   14 ( 5 )   797 - 802   2010年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Influence of direct laser writing with femtosecond pulses on electrochemical etching of n-type low conductivity (&gt; 1,000 Omega cm) silicon is demonstrated. It has been shown that thermal 1-A mu m-thick SiO(2) layer on silicon surface can be used as a protective layer in the electrochemical etching process. It has been found that laser ablation changes not only the surface morphology and structure of silicon samples but also the character of their anodic etching in aqueous solution of hydrofluoric acid. Formation of microvoids and caverns of irregular shape has been observed at the laser-ablated sites. It is proposed that the change of silicon conductivity from n- to p-type takes place at the laser fabricated regions. Processes of Si anodic oxidation and electrochemical etching are discussed.

    DOI: 10.1007/s10008-009-0852-z

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  • Erratum: Vibrations of microspheres probed with ultrashort optical pulses (Optics Letters (2009) 34 (3740)) 査読

    T. Dehoux, T. A. Kelf, M. Tomoda, O. Matsuda, O. B. Wright, K. Ueno, Y. Nishijima, S. Juodkazis, H. Misawa, V. Tournat, V. E. Gusev

    Optics Letters   35 ( 7 )   940   2010年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OSA Publishing  

    DOI: 10.1364/OL.35.000940

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  • Influence of localized surface plasmon resonance on shape changes of nanostructures: Investigation using metal nanoblocks in halide solutions 査読

    Takeshi Tsuji, Kosei Ueno, Yukie Yokota, Masaharu Tsuji, Hiroaki Misawa

    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY   212 ( 1 )   20 - 26   2010年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE SA  

    Photoinduced shape changes of metal nanostructures in halide solutions were investigated using gold and silver nanoblocks (NBs) patterned on a glass substrate, instead of nanoparticles dispersed in solution. It was found that size reduction of the NBs by halide etching was enhanced by photoirradiation. Furthermore, it was revealed that the halide etching efficiency corresponded to the intensity of the electric field induced by localized surface plasmon resonance (LSPR) of the NBs. The enhancement of halide etching by LSPR was explained on the basis of electron transfer reactions from metal NBs. Throughout this study, it was demonstrated that metal NBs fabricated on a substrate constitute a powerful system to investigate photoinduced shape changes of nanostructures, because of their defined shape, position, and configuration. (C) 2010 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jphotochem.2010.03.007

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  • Freestanding and movable photonic microstructures fabricated by photopolymerization with femtosecond laser pulses 査読

    Quan Sun, Saulius Juodkazis, Naoki Murazawa, Vygantas Mizeikis, Hiroaki Misawa

    JOURNAL OF MICROMECHANICS AND MICROENGINEERING   20 ( 3 )   035004   2010年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We present a method to fabricate freestanding and movable photonic microstructures by photopolymerization in a zirconium-based sol-gel hybrid resist with femtosecond laser three-dimensional (3D) direct writing. The freestanding microstructures exhibit much less distortion than the conventional structures attached to substrates, especially when made at close to the photopolymerization threshold. A few percent shrinkage which exists rescales the structure and it can lead to the shift of the photonic stop band toward shorter wavelengths. Fabrication of freestanding and freely movable (in micro-fluidic environment) 3D microstructures realizes a simple approach to quantitatively study the shrinkage of photopolymers and to improve the resolution. 3D-movable micro-optical elements with designed photonic properties and micro-devices have potential in opto-fluidics and opto-micro-mechanical applications based on laser trapping and manipulation.

    DOI: 10.1088/0960-1317/20/3/035004

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  • Modification of refractive index by a single femtosecond pulse confined inside a bulk of a photorefractive crystal 査読

    Eugene G. Gamaly, Saulius Juodkazis, Vygantas Mizeikis, Hiroaki Misawa, Andrei V. Rode, Wieslaw Krolikowski

    PHYSICAL REVIEW B   81 ( 5 )   054113   2010年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We demonstrate that the interaction of intense femtosecond pulse with photorefractive crystal at conditions close to the optical-breakdown threshold differs drastically from that of long pulse and cw illumination. Our theoretical estimations show that the high number density of excited electrons modifies the dielectric function leading to the transient negative change in the refractive index, Delta n/n(0)similar to-10(-2) that vanishes on nanosecond time scale. Moreover, the high-frequency laser field, two orders of magnitude larger than the field of spontaneous polarization, prevents the stationary charge distribution during the pulse. The diffusion and recombination of charge carriers continues over a nanosecond time scale, after the end of the pulse. The main driving force for the current after the pulse is the field of spontaneous polarization in the ferroelectric medium: the current terminates when the field of charge separation balances this field. We show here that the stationary modification of refractive index according to this model is then independent of the polarization of the pump light beam, in agreement with experiments, and saturates at Delta n approximate to 10(-3) in semiquantitative fit to the experimental data.

    DOI: 10.1103/PhysRevB.81.054113

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  • Nanogap-Assisted Surface Plasmon Nanolithography 査読

    Kosei Ueno, Satoaki Takabatake, Yoshiaki Nishijima, Vygantas Mizeikis, Yukie Yokota, Hiroaki Misawa

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   1 ( 3 )   657 - 662   2010年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Nanoparticles of noble metals exhibit localized surface plasmons (LSP) associated with enhancement of the electromagnetic field due to its localization in nanometric domains at the surface of nanoparticles. Especially, nanogapmetallic structures show strong enhancement of the electromagnetic field at the nanogap position. This can be achieved up to 10(5) times larger than the incident light field. We have explored the possibility to use the localized field for nanogap-assisted surface plasmon nanolithography. For the purpose, monidisperse arrays consisting of pairs of rectangular gold nanoblocks separated by nanogaps were fabricated on glass substrates using electron beam lithography and lift-off techniques. Nanoblock structures were used as photomasks for contact exposure of thinfilms of positive photoresist on glass substrates. Thus, ordered clusters of nanoparticles separated by nanogaps can provide a stable and versatile platform for further development of optical subwavelength nanolithography. To the best of our knowledge, this is the first proof-of-principle demonstration of such a technique.

    DOI: 10.1021/jz9002923

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  • Redox Cycling Effect on the Surface-enhanced Raman Scattering Signal of Crystal Violet Molecules at Nanostructured Interdigitated Array Electrodes 査読

    Md Monirul Islam, Kosei Ueno, Hiroaki Misawa

    ANALYTICAL SCIENCES   26 ( 1 )   19 - 24   2010年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    Nanostructured interdigitated array (IDA) electrodes with different inter-electrode spacing were demonstrated to improve the detection sensitivity of short-lived electroactive species and to follow interfacial dynamics by their surface-enhanced Raman scattering (SERS) functionality. Nanostructured IDA electrodes fabricated using electron beam lithography were used for an electrochemical SERS study of irreversible electroactive species, crystal violet (CV), in an aqueous KCl solution in single and generation-collection (GC) mode experiments. The GC mode enabled us to amplify the SERS intensity. An inter-electrode spacing dependent study found the maximum number of redox cycling, collection efficiency and amplification of the SERS intensity. Its SERS function disclosed the potential-dependent dynamics of CV molecules at the electrode surface, which was not observed in the redox current. Miniaturized nanostructured IDA electrodes are of great importance for developing lab on chip devices, and are useful for analyzing dynamical features within small space/volume domains, which require small amounts and/or concentration of analytes.

    DOI: 10.2116/analsci.26.19

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  • Development of Interdigitated Array Electrodes with Surface-enhanced Raman Scattering Functionality 査読

    Md Monirul Islam, Kosei Ueno, Saulius Juodkazis, Yukie Yokota, Hiroaki Misawa

    ANALYTICAL SCIENCES   26 ( 1 )   13 - 18   2010年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    Interdigitated array electrodes with surface-enhanced Raman scattering (SERS) functionality for in situ qualitative and quantitative analysis of electroactive species are demonstrated. Gold nanostructured interdigitated array electrodes (NIDAEs) were fabricated by electron beam lithography, and used for an electrochemical SERS study of K(3)[Fe(CN(6))] in aqueous KClO(4) solution in single and generation-collection modes. The generation-collection mode experiment showed amplification of the SERS band intensity for adsorbed ferricyanide ions at the negative end of the applied potential, while in single mode it was reduced to near zero. This new finding reveals that NIDAEs offer a new opportunity for analytical science by improving analytical sensitivity and detection ability of electroactive species. The electric fields accumulating at nanogaps are promising for manipulating linear and nonlinear optical phenomena. In addition, miniaturized NIDAEs are of great importance for developing lab-on-a-chip devices, and are useful for measurements within small space/volume domains, requiring only small amounts and/or concentrations of analytes.

    DOI: 10.2116/analsci.26.13

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  • Fabrication of micro- and nano-structures in thin metallic films by femtosecond laser ablation 査読

    Vygantas Mizeikis, Saulius Juodkazis, Kai Sun, Hiroaki Misawa

    ADVANCED FABRICATION TECHNOLOGIES FOR MICRO/NANO OPTICS AND PHOTONICS III   7591   2010年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    We report maskless microfabrication of periodic structures in thin metallic films by femtosecond laser ablation. Two-dimensional (2D) triangular arrays of circular apertures with diameter of about 0.6 - 0.8 mu m and a lattice period of 1.0 and 2.0 mu m were fabricated by single-and multiple laser pulse ablation of 35 nm thick gold films sputtered on glass substrates. Optical transmission spectra of the fabricated samples exhibit transmission bands at infrared wavelengths. Theoretical modeling of the optical properties by Finite-Difference Time-Domain (FDTD) technique indicates that these bands are associated with localized and propagating surface plasmon (SP) modes. FDTD simulations also indicate substantial resonant enhancement of the near-field intensity at the metal's surface. Laser ablation of thin metallic films is therefore a promising route for fast prototyping of planar metallic micro-and nano-structures applicable as frequency-selective surfaces (FSS) and SP substrates.

    DOI: 10.1117/12.843074

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  • Femtosecond laser photopolymerization of photonic and free-movable microstructures in sol-gel hybrid resist 査読

    Quan Sun, Saulius Juodkazis, Naoki Murazawa, Vygantas Mizeikis, Hiroaki Misawa

    Proceedings of SPIE - The International Society for Optical Engineering   7591   75910K   2010年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE  

    We present the fabrication of microstructures for photonic and micro-/opto-fluidic applications using femtosecond laser 3D direct writing technique in zirconium-based sol-gel hybrid resist. The advantages and mechanism of photo-polymerization of this new material under fs-pulsed laser exposure are discussed. We suggest and achieve a novel method to fabricate free-standing and movable photonic microstructures, which exhibit much less distortion than the conventional structures attached to substrates, especially when made at close to the photopolymerization threshold. Fabrication of free-movable structures allows us to quantitatively study the shrinkage of photoresist and to improve the resolution. It also contributes to tuning the stop band position of photonic crystals to shorter wavelength. Furthermore, the demonstrated freely-movable property makes it possible to laser trap and manipulate photonic microstructures and have potential application in optofluidics and bio-applications. © 2010 Copyright SPIE - The International Society for Optical Engineering.

    DOI: 10.1117/12.840657

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  • Effect of drying process on photon-polymerized microstructures in resists

    Quan Sun, Hidenori Asahi, Naoki Murazawa, Kosei Ueno, Hiroaki Misawa

    2010 OSA-IEEE-COS Advances in Optoelectronics and Micro/Nano-Optics, AOM 2010   2010年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    We present the fabrication of photonic microstructures using femtosecond laser direct writing technique in resist. The effect of drying process on photo-polymerized microstructures is investigated. We find that shrinkage mostly arises during the drying process.

    DOI: 10.1109/AOM.2010.5713579

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  • High sensitivity biosensing using nano-slot nanolaser 査読

    Shota Kita, Shoji Hachuda, Toshihiko Baba, Tatsuro Endo, Yoshiaki Nishijima, Hiroaki Misawa

    Proceedings of IEEE Sensors   2303 - 2306   2010年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IEEE  

    We have developed photonic crystal nanolaser and applied it to sensing liquids and bio-molecules. In this study, a nano-slot structure is introduced into the nanolaser, which strengthens the mode localization and improves the sensitivity, stability, and resolution as a sensor. As a result, a very low detection limit of 5.1 pg/ml has been achieved for BSA protein. It will be applicable to high-throughput label-free biosensing, while a mechanism of such low detection limit with the nano-slot is of great interest to investigate. ©2010 IEEE.

    DOI: 10.1109/ICSENS.2010.5690745

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  • Vibrations of microspheres probed with ultrashort optical pulses 査読

    T. Dehoux, T. A. Kelf, M. Tomoda, O. Matsuda, O. B. Wright, K. Ueno, Y. Nishijima, S. Juodkazis, H. Misawa, V. Tournat, V. E. Gusev

    OPTICS LETTERS   34 ( 23 )   3740 - 3742   2009年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    We use ultrashort optical pulses to excite and detect vibrations of single silica spheres with a diameter of 5 mu m placed at the surface of an acoustically mismatched substrate. In addition to the photoelastic detection of picosecond longitudinal acoustic pulses propagating inside the bulk, we detect gigahertz acoustic resonances of the sphere through probe beam defocusing. The mode frequencies are in close accord with those calculated from the elastic vibrations of a free sphere. We also record a resonant enhancement in the amplitude of specific modes of two touching spheres. (C) 2009 Optical Society of America

    DOI: 10.1364/OL.34.003740

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  • High-fidelity fractionation of ssDNA fragments differing in size by one-base on a spiral-channel electrophoretic chip 査読

    Kai Sun, Nobuko Suzuki, Zheyu Li, Ryoko Araki, Kosei Ueno, Saulius Juodkazis, Masumi Abe, Sumihare Noji, Hiroaki Misawa

    ELECTROPHORESIS   30 ( 24 )   4277 - 4284   2009年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    For the fractionation of fragments of interest from selective PCR products generated by high coverage gene expression profiling (HiCEP) analysis, high-resolution with the ability to discriminate and fractionate fragments differing by one base (base pair) in size is highly required. We report here on a new 4-inch diameter spiral-channel chip device for automatic high-fidelity fractionation. Overlapping DNA fragments of 180, 181 and 182 bases, with only one-base difference in size, were successfully fractionated. The collected fragments were PCR amplified, and then evaluated by size checking analysis, DNA sequencing, and homolog search. The high-resolution fractionation has been achieved because of the combined contributions of (i) the high-resolution separation using a 30 cm long spiral channel, (ii) a blocking technique to avoid contamination from unselected fragments during CE, and (iii) precise micro-scale target extraction. Contaminations due to unselected fractions have been greatly decreased to a negligible level by optimization of the extraction position and extraction time corresponding to the targeted segment only. This technique can be adapted to a wide range of applications, such as protein or cell collections where requirements for the high purity are more important than the amount of recovered fractionated material.

    DOI: 10.1002/elps.200900455

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  • Formation of amorphous sapphire by a femtosecond laser pulse induced micro-explosion 査読

    Vygantas Mizeikis, Shigeru Kimura, Nikolay V. Surovtsev, Vygandas Jarutis, Akira Saito, Hiroaki Misawa, Saulius Juodkazis

    APPLIED SURFACE SCIENCE   255 ( 24 )   9745 - 9749   2009年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We report on structural characterization of void-structures created by a micro-explosion at the locus of a tightly focused femtosecond laser pulse inside the crystalline phase of Al(2)O(3) (R3c space group). The transmission electron microscopy (TEM), micro-X-ray diffraction (XRD) analysis, and Raman scattering revealed a presence of strongly structurally modified amorphous regions around the void-structures. We discuss issues of achieving the required resolution for structural characterization and assignment of newly formed phases of nano-crystallites by TEM, XRD, and Raman scattering from micro-volumes of modified materials enclosed inside the bulk of the host phase. (C) 2009 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.apsusc.2009.04.063

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  • Optical and ultrasonic monitoring of femtosecond laser filamentation in fused silica 査読

    Vygantas Mizeikis, Saulius Juodkazis, Tadas Balciunas, Sergey I. Kudryashov, Vladimir D. Zvorykin, Andrei A. Ionin, Hiroaki Misawa

    APPLIED SURFACE SCIENCE   255 ( 24 )   9721 - 9723   2009年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Millimeter-long filaments and accompanying luminous plasma and defect channels created in fused silica (FS) by single focused femtosecond laser pulses with supercritical powers were probed in situ using optical imaging and contact ultrasonic techniques. Above the threshold pulse energy E(opt) = 5 mu J corresponding to a few megawatt power levels pulses collapse due to self-focusing, producing channels filled by electron-hole plasma and luminescent defects, and exhibits predominantly compressive pressure transients. Analysis of the optical and ultrasonic response versus the laser pulse energy suggests that filamentary pulse propagation in the channels occurs with considerable dissipation of about similar to 10 cm (1). The predominant ionization mechanism is most likely associated with avalanche ionization, while the main mechanism of optical absorption is free-carrier absorption via inverse Bremsstrahlung interaction with the polar lattice. (C) 2009 Elsevier B.V. All rights reserved.

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  • Three-dimensional microfabrication of materials by femtosecond lasers for photonics applications 査読

    Saulius Juodkazis, Vygantas Mizeikis, Hiroaki Misawa

    JOURNAL OF APPLIED PHYSICS   106 ( 5 )   051101   2009年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    Femtosecond laser fabrication of three-dimensional structures for photonics applications is reviewed. Fabrication of photonic crystal structures by direct laser writing and holographic recording by multiple beam interference techniques are discussed. The physical mechanisms associated with structure formation and postfabrication are described. The advantages and limitations of various femtosecond laser microfabrication techniques for the preparation of photonic crystals and elements of microelectromechanical and micro-optofluidic systems are discussed.

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  • Optical Vortices from Liquid Crystal Droplets 査読

    Etienne Brasselet, Naoki Murazawa, Hiroaki Misawa, Saulius Juodkazis

    PHYSICAL REVIEW LETTERS   103 ( 10 )   103903   2009年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We report on the generation of mono- and polychromatic optical phase singularities from micron-sized birefringent droplets. This is done experimentally by using liquid crystal droplets whose three dimensional architecture of the optical axis is controlled within the bulk by surfactant agents. Because of its microscopic size these optical vortex generators are optically trapped and manipulated at will, thus realizing a robust self-aligned micro-optical device for orbital angular momentum conversion. Experimental observations are supported by a simple model of optical spin-orbit coupling in uniaxial dielectrics that emphasizes the prominent role of the transverse optical anisotropy with respect to the beam propagation direction.

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  • Nano-textured metallic surfaces for optical sensing and detection applications 査読

    Yukie Yokota, Kosei Ueno, Saulius Juodkazis, Vygantas Mizeikis, Naoki Murazawa, Hiroaki Misawa, Haruya Kasa, Kenji Kintaka, Junji Nishii

    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY   207 ( 1 )   126 - 134   2009年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE SA  

    This work describes fabrication of three-dimensionally nano-textured silicon surface structures metalized by thin gold films,and their application for optical sensing and detection of solute molecules utilizing surface-enhanced Raman scattering (SERS) effect. Two types of sensitive surfaces were prepared by different techniques. The first of them was a checkerboard pattern of 3D nanoblocks defined in compact areas on the surface of a silicon wafer using highly accurate electron-beam lithography (EBL) technique, and fabricated by dry reactive-ion etching (RIE) technique with subsequent metalization of the surface by gold sputtering. The second type of sensitive surface consisted of a square array of nano-apertures. defined on a large area of the silicon surface by a less accurate but simpler ultraviolet holographic lithography, and subsequently fabricated in a sequence of dry and wet etching as well as gold sputtering steps. The fabricated structures were found to exhibit significant near-field enhancement, as evidenced by strong SERS signal from the sensors immersed in aqueous pyridine solutions with concentrations as low as 10(-9) M due to the presence of well-defined 3D periodic texture of the structure. (C) 2008 Elsevier BY. All rights reserved.

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  • Near-IR vibrational dynamics of periodic gold single and pair nanocuboids 査読

    Li Wang, Yoshiaki Nishijima, Kosei Ueno, Hiroaki Misawa, Naoto Tamai

    APPLIED PHYSICS LETTERS   95 ( 5 )   053116   2009年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    We examined vibrational dynamics of periodic gold single and pair nanocuboids with 9 nm separation at 400 nm excitation by near-IR transient absorption spectroscopy. The similar oscillation periods of coherent phonon vibration (77 +/- 1 ps) were observed for both nanocuboids while the damping of the pair was faster than that of the single. From the analysis of bleaching peak shift and finite-difference time-domain calculation, the lattice change in coherent phonon vibration was estimated to be +/- 1% for a quasiextensional and +/- 3% for an quasibreathing modes of a single nanocuboid.

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  • Optical transmission and laser structuring of silicon membranes 査読

    Saulius Juodkazis, Yasufumi Nishi, Hiroaki Misawa, Vygantas Mizeikis, Olivier Schecker, Reimar Waitz, Paul Leiderer, Elke Scheer

    OPTICS EXPRESS   17 ( 17 )   15308 - 15317   2009年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    The optical linear and nonlinear properties of similar to 340-nm-thick Si membranes were investigated. The investigation included both experiments in which the reflection and transmission from the membranes were measured, and finite differences time domain simulations. The linear optical transmission of the Si membranes can be controlled by changing the thickness of a thermally grown oxide on the membrane. Illumination of the membranes with high levels of irradiation leads to optical modifications that are consistent with the formation of amorphous silicon and dielectric breakdown. When irradiated under conditions where dielectric breakdown occurs, the membranes can be ablated in a well-controlled manner. Laser micro-structuring of the membranes by ablation was carried out to make micrometer-sized holes by focused fs-pulses. Ns-pulses were also used to fabricate arrays of holes by proximity-ablation of a closely-packed pattern of colloidal particles. (C) 2009 Optical Society of America

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  • Preface to the hiroshi masuhara festschrift: Exploration with lasers into New Areas of molecular photoscience 査読

    Paul F. Barbara, Johan Hofkens, Hiroaki Misawa, Kei Murakoshi, Tsuyoshi Asahi, Hiroshi Miyasaka

    Journal of Physical Chemistry C   113 ( 27 )   11425 - 11427   2009年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Nanoparticle-Enhanced Photopolymerization 査読

    Kosei Ueno, Saulius Juodkazis, Toshiyuki Shibuya, Vygantas Mizeikis, Yukie Yokota, Hiroaki Misawa

    JOURNAL OF PHYSICAL CHEMISTRY C   113 ( 27 )   11720 - 11724   2009年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Photopolymerization of commercial photoresist SU-8 assisted by plasmonic near-field enhancement in nanogaps separating gold nanoblocks was investigated. Photopolymerization rates enhanced by orders of magnitude were found in gold nanoblock structures with nanogaps narrower than 10 nm. The mechanisms responsible for local and nonlocal nonlinear photopolymerization of SU-8 are discussed.

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  • Is the nano-explosion really microscopic? 査読

    Saulius Juodkazis, Hiroaki Misawa, Eugene G. Gamaly, Barry Luther-Davies, Ludovic Hallo, Philippe Nicolai, Vladimir T. Tikhonchuk

    JOURNAL OF NON-CRYSTALLINE SOLIDS   355 ( 18-21 )   1160 - 1162   2009年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    It is demonstrated that the processes leading to nano-void formation under single-pulse tight focusing in dielectrics are described by the same laws used to describe macroscopic explosions but with energies 10(21) times lower and space and time scales reduced by 10(7). (C) 2009 Elsevier B.V. All rights reserved.

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  • Optical and ultrasonic signatures of femtosecond pulse filamentation in fused silica 査読

    Vygantas Mizeikis, Saulius Juodkazis, Tadas Balciunas, Hiroaki Misawa, Sergey I. Kudryashov, Vladimir D. Zvorykin, Andrei A. Ionin

    JOURNAL OF APPLIED PHYSICS   105 ( 12 )   123106   2009年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    Millimeter-long filaments and accompanying luminous plasma and defect channels created in fused silica by single, moderately focused femtosecond laser pulses with supercritical powers were probed in situ using optical imaging and contact ultrasonic techniques. Above the threshold pulse energy E-opt = 5 mu J corresponding to a few megawatt power, the pulses collapse due to self-focusing and the nonlinear focus moves upstream with increasing pulse energy. Behind the focus, elongated, gradually narrowing awl-shaped channels of electron-hole plasma and luminescent defects are produced. In the channels, whose dimensions generally depend on the pulse energy, supercontinuum emission propagating downstream the channels occurs, although its observation requires elevated pulse energies above 25 mu J in order to compensate energy dissipation in the channels. Ultrasonic side-view imaging of the channels, conducted from a few millimeters distance, reveals predominantly compressive pressure transients. The compressive signals are observed above the same threshold pulse energy E-opt, and their amplitude increases linearly with the laser pulse energy, simultaneously exhibiting significant temporal broadening of the corresponding pulsewidths, reflecting square root dependence of the channel length and sublinear (proportional to E-3/4) dependence of the source pressure on the pulse energy. Altogether, these optical and ultrasonic studies demonstrate filamentary pulse propagation with considerable dissipation (similar to 10 cm(-1)) in the awl-shaped subcritical plasma channels rich with generated point defects and optical damage sites. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3148249]

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  • Suppression of ripples on ablated Ni surface via a polarization grating 査読

    Hideo Iwase, Satoshi Kokubo, Saulius Juodkazis, Hiroaki Misawa

    OPTICS EXPRESS   17 ( 6 )   4388 - 4396   2009年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    Gratings were recorded on the surface of nickel by ablation without formation of ripples using an interference of two p-polarized femtosecond laser beams at a pi/4 angle of incidence. The mechanism of ripples' suppression is explained by formation of a polarization grating and by ablation at the locations where the polarization is normal to the Ni surface. The aspect ratio of the ablated grooves was similar to 3 with the period similar to 570 nm at the central wavelength of irradiation of 800 nm. This method is applicable for laser structuring of different materials and a recorded grating structure can be scaled with the irradiation wavelength. (C) 2009 Optical Society of America

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  • Lasing with well-defined cavity modes in dye-infiltrated silica inverse opals 査読

    Yoshiaki Nishijima, Kosei Ueno, Saulius Juodkazis, Vygantas Mizeikis, Hideki Fujiwara, Keiji Sasaki, Hiroaki Misawa

    OPTICS EXPRESS   17 ( 4 )   2976 - 2983   2009年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    Lasing in dye solution-embedded inverse silica opal structures was investigated. The opal films were prepared by sedimentation of polystyrene microspheres on a cover glass. The polystyrene structures were inverted using sol-gel infiltration of silica and subsequent removal of polystyrene. Photoluminescence of rhodamine ( rhodamine B, 6G and sulfo-rhodamine 101) dye solutions embedded into the inverse silica opal structures exhibited clear signatures of the lasing via a distributed feedback (DFB) and gain modulation. The refractive index contrast between the dye and the inverse opal was small enough (similar to 0.03%) for the formation of refractive index coupling between the lasing modes. The lasing spectrum exhibited a highly regular periodic structure of modal peaks, rather than the chaotic superposition of peaks reported in previous studies. Lasing modes having a spectral width of about 0.25 nm and a free spectral range of about 0.75 nm appeared at the position of the maximum gain ( the maximum fluorescence of the dye). (c) 2009 Optical Society of America

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  • Spatially Selective Nonlinear Photopolymerization Induced by the Near-Field of Surface Plasmons Localized on Rectangular Gold Nanorods 査読

    Naoki Murazawa, Kosei Ueno, Vygantas Mizeikis, Saulius Juodkazis, Hiroaki Misawa

    JOURNAL OF PHYSICAL CHEMISTRY C   113 ( 4 )   1147 - 1149   2009年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Qualitative resemblance between photopolymerization patterns induced in a commercial photoresist SU-8 by optical near-field of surface plasmons localized on rectangular gold nanorods was observed. This finding indicates the possibility of a fast qualitative near-field imaging by embedding metallic nanoparticle structures into photopolymerizeable media and examining the shapes of polymerized regions using high-resolution electron-scanning or atomic force microscopies following the optical exposure.

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  • Segregation of Molecules in Lipid Bilayer Spreading through Metal Nanogates 査読

    Hideki Nabika, Naozumi Iijima, Baku Takimoto, Kosei Ueno, Hiroaki Misawa, Kei Murakoshi

    ANALYTICAL CHEMISTRY   81 ( 2 )   699 - 704   2009年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    A new methodology for nanoscopic molecular filtering was developed using a substrate with a periodic array of metallic nanogates with various widths between 75 and 500 nm. A self-spreading lipid bilayer was employed as the molecular transport and filtering medium. Dye-labeled molecules doped in the self-spreading lipid bilayer were filtered after the spreading less than a few tens of micrometers on the nanogate array. Quantitative analysis of the spreading dynamics suggests that the filtering effect originates from the formation of the chemical potential barrier at the nanogate region, which is believed to be due to structural change such as compression imposed on the spreading lipid bilayer at the gate. A highly localized chemical potential barrier affects the ability of the doped dye-labeled molecules to penetrate the gate. The use of the self-spreading lipid bilayer allows molecular transportation without the use of any external field such as an electric field as is used in electrophoresis. The present system could be applied micro- and nanoscopic device technologies as it provides a completely nonbiased filtering methodology.

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  • Three-dimensional femtosecond laser fabrication 査読

    S. Juodkazis, V. Mizeikis, Y. Nishijima, W. Ebina, H. Misawa, M. Kondo, V. Švrček

    ECS Transactions   16 ( 41 )   57 - 63   2009年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    We report on the incorporation of silicon nanocrystals (nc-Si) into the photo-polymer resist SU8 by direct laser writing using femtosecond laser pulses and on the holographic formation of nano-/micro-textured surfaces by interference of several beams forming patterns with wide range of spatial frequencies. These approaches open possibility for a three-dimensional (3D) architectures of micro-structures potentially useful for active optical and fluidic micro-devices. © The Electrochemical Society.

    DOI: 10.1149/1.3104710

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  • 3P1-18

    Tomoda Motonobu, Matsueda Shinnosuke, Wright Oliver B, Matsuda Osamu, Nishijima Yoshiaki, Ueno Kosei, Saulius Juodkazis, Misawa Hiroaki

    Proceedings of Symposium on Ultrasonic Electronics   2009年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Ultrafast laser induced microexplosion: A new strategy to synthesise super-dense nanomaterials 査読

    Saulius Juodkazis, Hiroaki Misawa, G. Eugene Gamaly, V. Andrei Rode

    CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference   2009年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    DOI: 10.1109/CLEOE-EQEC.2009.5192211

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  • Femtosecond laser interaction with photo-refractive crystals: High frequency field and internal field contributions to the refractive index changes 査読

    S. Juodkazis, E. G. Gamaly, V. Mizeikis, H. Misawa, A. V. Rode, W. Z. Krolikowski, K. Kitamura

    CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference   2009年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    DOI: 10.1109/CLEOE-EQEC.2009.5196280

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  • Metalo-dielectric 3D photonic crystals prepared by metalization of opticaly microfabricated polymeric templates 査読

    Vygantas Mizeikis, Rima Tarozaite, Saulius Juodkazis, Hiroaki Misawa

    ADVANCED FABRICATION TECHNOLOGIES FOR MICRO/NANO OPTICS AND PHOTONICS II   7205   2009年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    Metalo-dielectric photonic crystals (MDPC) were fabricated by the combination of direct laser writing technique, which was used to prepare initial dielectric templates, and by subsequent metalization of the templates using electroless coating technique. The obtained MDPC structures have adequate structural quality, and exhibit spectral signatures of photonic bands consistent with theoretical expectations. The fabrication process is simple but reliable, and can deliver MDPC structures suitable for operation in the infrared and terahertz spectral ranges.

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  • Monitoring of microplasma formation and filamentation of tightly focused femtosecond laser pulses in dielectrics 査読

    Eugenijus Gaizauskas, Vygantas Mizeikis, Hiroaki Misawa, Sergey I. Kudryashov, Vladimir D. Zvorykin, Andrei A. Ionin, Saulius Juodkazis

    ULTRAFAST PHENOMENA IN SEMICONDUCTORS AND NANOSTRUCTURE MATERIALS XIII   7214   2009年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    Generation of free-carrier plasma and filamentation of the ultra-short laser pulse were investigated and modeled. Experimental results of filamentation are supported by numerical model which takes into account accumulation of refractive index modifications due to multi-pulse exposure. A contact acoustic monitoring technique was employed to perform spatially-resolved in situ detection of micro-plasma formation and filamentation of focused femtosecond laser pulses with critical and sub-critical powers in glass. The recorded acoustic signals reveal free-carrier generation mechanisms associated with the formation of plasma and filamentation of the propagating laser pulses. Optical opacity of the plasma region, which sets in at the irradiance of a few kJ/cm(3) (close to the dielectric breakdown threshold) using pulse focusing optics with numerical aperture NA = 0.75, reveals its critical character, and allows the estimation of acoustic pressure in the similar to GPa range. The pressure depended on the irradiance as P similar to I-0.59. In the case of loose focusing (NA = 0.035) filamentation of fs-pulses occurred at sub-critical plasma density with P similar to I. Detection and interpretation of these acoustic signatures thus enable real-time in situ monitoring of optical ionization, pulse filamentation in bulk dielectrics under the irradiation by femtosecond laser pulses.

    DOI: 10.1117/12.808856

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  • Light-Induced Nonlinear Rotations of Nematic Liquid Crystal Droplets Trapped in Laser Tweezers 査読

    Etienne Brasselet, Tadas Balciunas, Naoki Murazawa, Saulius Juodkazis, Hiroaki Misawa

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   512   1989 - 1997   2009年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:TAYLOR & FRANCIS LTD  

    We report on optically induced rotations of nematic liquid crystal droplets. We show experimentally that bipolar nematic liquid crystal droplets trapped in laser tweezers having circular polarization can exhibit nonlinear rotational motion, unlike optically trapped solid birefringent micro-plates. Such nonlinear rotations are retrieved by analyzing the polarization dynamics analysis of the light beam after it has passed through the droplet. The occurrence of complex dynamics is only found for large enough trapping power and droplet diameter. The analogy with optically induced nonlinear rotations in nematic liquid crystal films is briefly discussed.

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  • Hard X-ray generation using femtosecond irradiation of PbO glass 査読

    Koji Hatanaka, Ken-ichiro Yomogihata, Hiroshi Ono, Kei Nagafuchi, Hiroshi Fukumura, Michiko Fukushima, Tomohiro Hashimoto, Saulius Juodkazis, Hiroaki Misawa

    JOURNAL OF NON-CRYSTALLINE SOLIDS   354 ( 52-54 )   5485 - 5490   2008年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have generated hard X-rays by front- and back-side femtosecond laser irradiation of PbO-rich glass. The actual Pb content of glasses was corroborated by Pb M-line emission intensities with an uncertainty of less than 20%. The elements K and As at concentrations of a few mol% were detected. X-ray generation by back-side irradiation helped to avoid an air breakdown; however, self-focusing and filamentation limited the achievable light intensity and effectiveness of X-ray generation. Characteristics and mechanisms of X-ray generation from the front- and back-side of glasses are discussed. (C) 2008 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jnoncrysol.2008.09.013

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  • Femtosecond laser-assisted formation of channels in sapphire using KOH solution 査読

    Saulius Juodkazis, Yasufumi Nishi, Hiroaki Misawa

    PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS   2 ( 6 )   275 - 277   2008年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    We report on wet etching of photomodified regions in crystalline sapphire using KOH solution. Tightly focused femtosecond laser pulses (150 fs at 800 nm wavelength) were used to create void structures enclosed in an amorphised sapphire shell inside the bulk of a crystalline host. The diameter of the amorphous regions can be controlled by pulse energy and was typically 0.5-1.5 mu m. The etching rate depends on the distance between adjacent irradiation spots, pulse energy, concentration of etchant and ultrasonic agitation.

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  • Laser processing of sapphire by strongly focused femtosecond pulses 査読

    Saulius Juodkazis, Hiroaki Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   93 ( 4 )   857 - 861   2008年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    The high-temperature annealing (1500 degrees C for 15 min) of the shock-amorphized and compressed sapphire around the voids rendered the amorphous sapphire insoluble in aqueous solution of hydrofluoric acid. There were no observable back relaxation and reflow of the compressed amorphous phase. The overlapping of femtosecond pulses by &gt; 70% of the focal diameter also made the photomodified regions insoluble in aqueous solution of hydrofluoric acid. Femtosecond laser cutting of hard dielectric materials is discussed.

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  • Electrophoretic chip for fractionation of selective DNA fragment 査読

    Kai Sun, Nobuko Suzuki, Zheyu Li, Ryoko Araki, Kosei Ueno, Saulius Juodkazis, Masumi Abe, Sumihare Noji, Hiroaki Misawa

    ELECTROPHORESIS   29 ( 19 )   3959 - 3963   2008年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-BLACKWELL  

    A microchannel chip has been used to fractionate selected segments from an electrophoretic flow of separated fragments. A sample, which covers the size from 35 to 670 bp, was initially separated using an 8.8-cm-long channel at the electric field strength of 100 V/cm. The target fragment of 318 bp was selected and extracted from the separation channel. High-resolution fractionation was achieved by introducing new procedures for blocking, extraction, and segment transfer. Fractionation quality with and without blocking were compared using a 310 Genetic Analyzer (Applied Biosystems). The results show that no contamination was found in the sample, which was fractionated with blocking; however, a contamination by short segments was found in the sample, which was fractionated without blocking. Furthermore, fractionation by the chip was found to be of higher fidelity than that by the polyacrylamide slab gel, which displayed a small overlapped peak after the target peak. Compared with the traditional method, our chips enable faster and high-fidelity fractionation, thus providing a new toot for bioanalysis and other applications.

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  • Laser induced memory bits in photorefractive LiNbO3 and LiTaO3 査読

    Saulius Juodkazis, Vygantas Mizeikis, Markas Sudzius, Hiroaki Misawa, Kenji Kitamura, Shunji Takekawa, Eugene G. Gamaly, Wieslaw Z. Krolikowski, Andrei V. Rode

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   93 ( 1 )   129 - 133   2008年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    We study experimentally the formation of refractive index voxels (volume elements) in photorefractive LiNbO3 and LiTaO3 crystals illuminated with high irradiance femtosecond laser pulses. We used 150 fs pulses at 800 nm wavelength (energy 6-50 nJ) tightly focused inside the crystals in a single shot regime. This resulted in a formation of a micrometer size region of elevated refractive index, which may be used as memory bits in information storage/retrieval application. The maximum refractive index change of 5x10(-4) was recorded in undoped LiNbO3 at an average light intensity of similar to TW/cm(2) that is close to the breakdown threshold. A simple setup for photorefractive recording and in situ monitoring of the refractive index changes has been proposed.

    DOI: 10.1007/s00339-008-4641-9

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  • Tunable single-mode photonic lasing from zirconia inverse opal photonic crystals 査読

    Yoshiaki Nishijima, Keisei Ueno, Saulius Juodkazis, Vygantas Mizeikis, Hiroaki Misawa, Mitsuru Maeda, Masashi Minaki

    OPTICS EXPRESS   16 ( 18 )   13676 - 13684   2008年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    Lasing from zirconia inverse opal photonic crystal structures infiltrated by solutions of rhodamine dyes was found to exhibit single-mode lasing peaks with spectral width less than 1 nm and quality factor in excess of 4000. The lasing occurs within the approximate range of high-reflectance spectral region associated with photonic stop band along &lt; 111 &gt; crystallographic direction, but its wavelength is not fixed to the corresponding Bragg wavelength of the periodic structure, and depends on the spectral position of the gain band. This lasing regime can be useful for realizing tunable single-mode photonic crystal lasers. (c) 2008 Optical Society of America.

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  • Chirp effect in hard X-ray generation from liquid target when irradiated by femtosecond pulses 査読

    Koji Hatanaka, Takahito Ida, Hiroshi Ono, Shin-ichi Matsushima, Hiroshi Fukumura, Saulius Juodkazis, Hiroaki Misawa

    OPTICS EXPRESS   16 ( 17 )   12650 - 12657   2008年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    The chirp effect on a X-ray emission intensity from a CsCl aqueous solution jet irradiated by femtosecond pulses was systematically studied. The p-polarized chirped pulses were more efficient as compared with the shortest pulses determined by the spectral bandwidth. The negatively-chirped pulses of approximately 240 fs duration produced up to 10 times larger X-ray intensity as compared with the transform-limited 160 fs pulses. The angular dependence of X-ray generation can be explained by the resonant absorption. Numerical simulations of electron density evolution due to the avalanche and multi-photon absorption supports qualitatively well the experimental observations. (c) 2008 Optical Society of America.

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  • Nano-structured materials in plasmonics and photonics 査読

    Kosei Ueno, Yukie Yokota, Saulius Juodkazis, Vygantas Mizeikis, Hiroaki Misawa

    CURRENT NANOSCIENCE   4 ( 3 )   232 - 235   2008年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:BENTHAM SCIENCE PUBL LTD  

    We investigate functional capabilities of large arrays of gold and silver nanorods as elements of plasmonic devices. The samples were fabricated by electron beam lithography and lift-off techniques on glass substrates. The areas patterned by the nanorods or other nanoparticles can be large, with dimensions of up to about one centimeter. Structural and optical characterization has allowed confirmation of a high homogeneity of the fabricated ensembles of nanorods, and a high sensitivity of their longitudinal extinction bands to the variations of the nanorod length and the refractive index of the environment. Applications of nanorods as refractive-index sensors is discussed.

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  • Templating and replication of spiral photonic crystals for silicon photonics (Invited paper) 査読

    Kock Khuen Seet, Vygantas Mizeikis, Kenta Kannari, Saulius Juodkazis, Hiroaki Misawa, Nicolas Tetreault, Sajeev John

    IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS   14 ( 4 )   1064 - 1073   2008年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    This paper describes femtosecond laser lithography of 3-D photonic crystal templates in commercial photoresist SU-8 and replication of these templates with silicon. Using this approach, silicon-based photonic crystals having 3-D square spiral architecture and exhibiting photonic stop gaps near the 2.5-mu m wavelength were fabricated. Possibilities to use a multiple-beam interference technique for two-photon absorption templating of photonic crystals are explored.

    DOI: 10.1109/JSTQE.2008.922909

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  • Correlation between cell morphology and aggrecan gene expression level during differentiation from mesenchymal stem cells to chondrocytes 査読

    Mutsumi Takagi, Takayuki Kitabayashi, Satoru Koizumi, Haruka Hirose, Shin-ichi Kondo, Masashi Fujiwara, Kosei Ueno, Misawa Hiroaki, Yoichiroh Hosokawa, Hiroshi Masuhara, Shigeyuki Wakitani

    BIOTECHNOLOGY LETTERS   30 ( 7 )   1189 - 1195   2008年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    A morphological parameter of polygonal index was defined as the ratio of cell adhesion area versus the square of the major cell axis, and cells that had an adhesion area larger than 4000 mu m(2) and a polygonal index larger than 0.3 were considered large polygonal cells. Cell morphology tended to change from fibroblast-like to polygonal and the percentage of the large polygonal cells increased almost in proportion to aggrecan mRNA expression level during the differentiation culture of mesenchymal stem cells (MSCs) to chondrocytes. Approximately 80% of the large polygonal cells were negative for MSC marker (CD90, CD166) expression and the aggrecan mRNA expression level of the large polygonal cells was markedly higher than that of cells with other morphologies.

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  • Nanoparticle plasmon-assisted two-photon polymerization induced by incoherent excitation source 査読

    Kosei Ueno, Saulius Juodkazis, Toshiyuki Shibuya, Yukie Yokota, Vygantas Mizeikis, Keiji Sasaki, Hiroaki Misawa

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   130 ( 22 )   6928 - +   2008年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We demonstrate the possibility to achieve optical triggering of photochemical reactions via two-photon absorption using incoherent light sources. This is accomplished by the use of arrays of gold nanoparticles, specially tailored with high precision to obtain high near-field intensity enhancement.

    DOI: 10.1021/ja801262r

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  • Three-dimensional write-read-erase memory bits by femtosecond laser pulses in photorefractive LiNbO3 crystals 査読

    Eugene G. Gamaly, Saulius Juodkazis, Vygantas Mizeikis, Hiroaki Misawa, Andrei V. Rode, Wieslaw Z. Krolikowski, Kenji Kitamura

    CURRENT APPLIED PHYSICS   8 ( 3-4 )   416 - 419   2008年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We report on a three-dimensional single-shot optical recording by 150 fs pulses at 800 nm wavelength in Fe-doped and stoichiometric undoped LiNbO3. The highest refractive index modulation of similar to 10(-3) per single pulse has been achieved at close to the dielectric breakdown irradiance of similar to TW/cm(2), and was found to be independent of polarization of the writing beam. The quasi-permanent and rewritable bits have been demonstrated in Fe-doped LiNbO3. Recording in undoped stoichiometric LiNbO3 was of transient nature with full optical contrast recovery on a 0.1-1 s scale. The observed refractive index modulation is explainable by the photovoltaic effect in LiNbO3. (c) 2007 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.cap.2007.10.072

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  • Formation of nano-voids in transparent dielectrics by femtosecond lasers 査読

    Eugene G. Gamaly, Saullus Juodkazis, Hiroaki Misawa, Barry Luther-Davies, Andrei V. Rode, Ludovic Hallo, Philippe Nicolai, Vladimir T. Tikhonchuk

    CURRENT APPLIED PHYSICS   8 ( 3-4 )   412 - 415   2008年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Formation of three-dimensional (3D) patterns of 0.2-0.5 mu m diameter voids inside a transparent solid has been demonstrated. The nano-voids could be created with a spacing similar to 2 mu m thus suggesting the possibility of permanent 3D optical memory with density similar to 100 Gbit/cm(3). Extremely high pressures of similar to 10 TPa and temperatures up to 10(5) K can be produced by a single sub-picosecond laser pulse tightly focused inside transparent dielectrics. Analysis of the size of the void and the shock affected zone as a function of the deposited energy shows that the experimental results can be explicitly understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Therefore, the size of the void can be controlled and predicted by proper focusing conditions and laser parameters. (c) 2007 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.cap.2007.10.071

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  • Statics and dynamics of radial nematic liquid-crystal droplets manipulated by laser tweezers 査読

    Etienne Brasselet, Naoki Murazawa, Saulius Juodkazis, Hiroaki Misawa

    Physical Review E - Statistical, Nonlinear, and Soft Matter Physics   77 ( 4 )   041704   2008年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Laser manipulation of trapped radial 4′ -n-pentyl-4-cyanobiphenyl (5CB) nematic liquid-crystal droplets induced by molecular reordering is presented. We show experimentally that optical tweezers having linear, elliptical, or circular polarization can break the radial symmetry of the initial molecular organization inside a radial nematic droplet. Static distorted or twisted deformation modes and steady or unsteady nonlinear rotational dynamics are observed. Statics results are analyzed in terms of light-induced radial or left-right symmetry breaking effects associated with optical reorientation. The dynamical observations are compared with simulations from a slab analog model, for which orientational processes driven by optical nonlinearities can be accurately described. This study confirms that light-induced bulk reordering is an essential ingredient towards the understanding of the behavior of radial nematic liquid-crystal droplets in laser tweezers, as suggested by previous studies. © 2008 The American Physical Society.

    DOI: 10.1103/PhysRevE.77.041704

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  • Coupled laser molecular trapping, cluster assembly, and deposition fed by laser-induced Marangoni convection 査読

    Oleg A. Louchev, Saulius Juodkazis, Naoki Murazawa, Satoshi Wada, Hiroaki Misawa

    OPTICS EXPRESS   16 ( 8 )   5673 - 5680   2008年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    A coupled mechanism for molecular aggregation in a thin water solution film by laser-tweezers is suggested based on (i) simulation of light intensity distribution and (ii) order of magnitude analysis of heat and mass transport induced by Marangoni convection. The analysis suggests that the laser induced temperature distribution develops within 1 ms and Marangoni convection flow commences within 0.01-1 s, which increases by 1-2 orders of magnitude the mass transfer of dissolved molecules into the laser focus where they are trapped and aggregate by attractive van der Waals forces. This mechanism, considered for the particular case of polymer assembly, suggests that it can also be successfully applied for assembling other types of clusters and molecular aggregates from solutions. (C) 2008 Optical Society of America.

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  • Acoustic monitoring of microplasma formation and filamentation of tightly focused femtosecond laser pulses in silica glass 査読

    Sergey I. Kudryashov, Vladimir D. Zvorykin, Andrei A. Ionin, Vygantas Mizeikis, Saulius Juodkazis, Hiroaki Misawa

    APPLIED PHYSICS LETTERS   92 ( 10 )   101916   2008年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    Contact acoustic technique has been employed to perform spatially resolved in situ detection of microplasma formation and filamentation of tightly focused femtosecond laser pulses with supercritical pulse powers in bulk dielectrics, via corresponding acoustic emission. Investigation of acoustic generation mechanisms related to the plasma formation and filamentation effects reveals the critical character of the opaque microplasma and provides estimates of its gigapascal-level pressures and energy densities of a few kJ/cm(3). The acoustic measurement enables real-time in situ monitoring and revealing of basic mechanisms of ionization and filamentation in bulk dielectrics. (C) 2008 American Institute of Physics.

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  • Three-dimensional high-aspect-ratio recording in resist 査読

    Toshiaki Kondo, Saullus Juodkazis, Vygantas Mizeikis, Hiroaki Misawa

    JOURNAL OF NON-CRYSTALLINE SOLIDS   354 ( 12-13 )   1194 - 1197   2008年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We demonstrate a method of capillary force reduction during wet processing of three-dimensional structures photo-polymerized in resist by femtosecond pulses. A rinse in water was added as the final step of wet processing for recovery of free-standing photo-polymerized structures with feature sizes of similar to 100 nm. The hydrophobicity of resist was utilized for reduction of the capillary drainage force. We show a possibility of holographical recording of a three-dimensional woodpile structure, which has a good permeability and can be fabricated by the proposed modified wet processing. (c) 2007 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jnoncrysol.2006.11.048

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  • Clusters of closely spaced gold nanoparticles as a source of two-photon photoluminescence at visible wavelengths 査読

    Kosei Ueno, Saulius Juodkazis, Vygantas Mizeikis, Keiji Sasaki, Hiroaki Misawa

    ADVANCED MATERIALS   20 ( 1 )   26 - +   2008年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    Gold nanostructures consisting of nanoblocks separated by a few nanometer-wide gaps were fabricated, and found to exhibit strong photoluminescence due to enhancement of the optical near-field localized in the nanogaps. The fabricated structures demonstrate a nanostructured metallic material capable of efficient photoluminescence, whose efficiency can be adjusted by tailoring the nanogap width.

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  • Three-Dimensional Structuring of Resists and Resins by Direct Laser Writing and Holographic Recording 査読

    Saulius Juodkazis, Vygantas Mizeikis, Hiroaki Misawa

    PHOTORESPONSIVE POLYMERS I   213   157 - 206   2008年

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    記述言語:英語   掲載種別:論文集(書籍)内論文   出版者・発行元:SPRINGER-VERLAG BERLIN  

    Optical techniques for three-dimensional micro- and nanostructuring of transparent and photo-sensitive materials are reviewed with emphasis on methods of manipulation of the optical field, such as beam focusing, the use of ultrashort pulses, and plasmonic and near-field effects. The linear and nonlinear optical response of materials to classical optical fields as well as exploitation of the advantages of quantum lithography are discussed.

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  • Two-photon excitation of dye-doped liquid crystal by a CW-laser irradiation 査読

    Naoki Murazawa, Saulius Juodkazis, Hiroaki Misawa, Kenji Kamada

    Molecular Crystals and Liquid Crystals   489   310 - 319   2008年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We report on excitation of photoluminescence via two-photon absorption (2PA) in dye-doped liquid crystal droplets using tightly focused cw-laser illumination at 1064nm wavelength. The photoluminescence of the 2PA dye C40H54N2O2 (MBAPB) dispersed inside the 7CB liquid crystal host increases as square of the laser tweezers' irradiance. The 2PA cross-section of MBAPB was measured by femtosecond Z-scan method. The polarization and temperature dependence of the photoluminescence corroborated the presence on the dye's molecular alignment inside the nonpolar liquid crystal host. The molecular alignment via the host-dye interaction can be used for the laser manipulation of micro-objects (e.g., doped liquid crystal droplets) in micro-fluidic/mechanical applications.

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  • Reversible photomodification of LiNbO3 and LiTAO(3) by femtosecond laser pulses 査読

    Vygantas Mizeikis, Saulius Juodkazis, Markas Sudzius, Hiroaki Misawa, Eugene G. J. Gamaly, Andrei V. Rode, Wieslaw Z. Krolikowski, Kenji Kitamura

    PHOTONICS: DESIGN, TECHNOLOGY, AND PACKAGING III   6801   2008年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    We present experimental and theoretical study of refractive index modification induced by femtosecond laser pulses in photorefractive crystals. The single pulses with central wavelength of 800 nm, pulse duration of 150 fs, and energy in the range of 6-130 nJ, tightly focused into the bulk of Fe-doped LiNbO3 and stoichiometric LiTaO3 crystals induce refractive index change of up to about 10(-3) within the volume of about (2.0 x 2.0 x 8.0) mu m(3). The photomodification is independent of the polarization orientation with respect to the crystalline c-axis. The recorded region can be erased optically by a defocused low-intensity single pulse of the same laser. Recording and erasure can be repeated at the same position many times without loss of quality. These findings demonstrate the basic functionality of the ultrafast three-dimensional all-optical rewritable memory. Theoretically they are interpreted by taking into account electron photogeneration and recombination as well as formation of a space-charge field. The presented analysis indicates dominant role of photovoltaic effect for our experimental conditions, and suggests methods for controlling various parameters of the photomodified regions.

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  • Inhibition of multipolar plasmon excitation in periodic chains of gold nanoblocks 査読

    Kosei Ueno, Saulius Juodkazis, Vygantas Mizeikis, Dai Ohnishi, Keiji Sasaki, Hiroaki Misawa

    OPTICS EXPRESS   15 ( 25 )   16527 - 16539   2007年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    Periodically corrugated chains of gold nanoblocks, fabricated with high precision by electron-beam lithography and lift-off techniques, were found to exhibit optical signatures of particle plasmon states in which relative contribution of longitudinal multipolar plasmons is significantly lower than that in equivalent rectangular gold nanorods. Plasmonic response of periodic chains is dominated by dipolar plasmon modes, which in the absence of multipolar exciations are seen as background-free and spectrally well-resolved extinction peaks at infrared (IR) wavelengths. This observation may help improve spectral parameters of IR plasmonic sub-wavelength antennae. Comparative studies of plasmon damping and dephasing in corrugated chains of nanoblocks and smooth rectangular nanorods are also presented. (C) 2007 Optical Society of America.

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  • Mechanical properties and tuning of three-dimensional polymeric photonic crystals 査読

    Saulius Juodkazis, Vygantas Mizeikis, Kock Khuen Seet, Hiroaki Misawa, Ulrike G. K. Wegst

    91 ( 24 )   241904-241904-3   2007年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Inverse silica opal photonic crystals for optical sensing applications 査読

    Y. Nishijima, K. Ueno, S. Juodkazis, V. Mizeikis, H. Misawa, T. Tanimura, K. Maeda

    OPTICS EXPRESS   15 ( 20 )   12979 - 12988   2007年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    This work reports fabrication of inverse silica opal photonic crystal structures from direct polystyrene micro sphere opals using low-temperature sol-gel infiltration of silica, and examines performance of these photonic crystals as environmental refractive index sensors. Sensitivity of the spectral position and optical attenuation of photonic stop gaps is found to allow detection of the index changes by the amount of similar to 10(-3). The high value of sensitivity, which is comparable with those of other optical sensing techniques, along with simplicity of the optical detection setup required for sensing, and the low-temperature, energy-efficient fabrication process make inverse silica opals attractive systems for optical sensing applications. (c) 2007 Optical Society of America.

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  • Laser trapping of deformable objects 査読

    Naoki Murazawa, Saulius Juodkazis, Hiroaki Misawa, Hiroshi Wakatsuki

    OPTICS EXPRESS   15 ( 20 )   13310 - 13317   2007年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    We report the trapping and manipulation of bubbles in viscous glass melts through the use of a laser. This phenomenon is observed in bubbles tens of micrometers in diameter under illumination by low numerical aperture ( NA = 0.55). Once the bubble was centered on the optical axis, it was trapped and followed a lateral relocation of the laser beam. This phenomenon is explained by modifications of the bubble's shape induced by axial heating and a decrease in surface tension. It is shown that formation of a concave dimple on the bubble's front surface explains the observed laser trapping and manipulation. This mechanism of laser trapping is expected to take place in other deformable materials and can also be used to remove bubbles from melts or liquids. For this technique to be effective, the alteration of the bubble's shape should be faster than its expulsion out of the laser's point of focus. (C) 2007 Optical Society of America.

    DOI: 10.1364/OE.15.013310

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  • Azimuthal correlation of photon pairs generated in spontaneous parametric down-conversion 査読

    Vygandas Jarutis, Saulius Juodkazis, Vygantas Mizeikis, Hiroaki Misawa

    PHYSICAL REVIEW A   76 ( 4 )   043845   2007年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    Correlations between the entire conical spatial modes of signal and idler beams in a type II spontaneous parametric down-conversion (SPDC) under ultrashort pulse pumping are examined experimentally and theoretically. Statistical properties and theoretical analysis of "path-entangled" states formed using these beams suggest that the quantum state of SPDC photon pairs cannot be represented by a pure ensemble of identically prepared pairs.

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  • Enhanced two-photon absorption of chromophores confined in two-dimensional nanospace 査読

    Kenji Kamada, Yoshihiko Tanamura, Kosei Ueno, Koji Ohta, Hiroaki Misawa

    JOURNAL OF PHYSICAL CHEMISTRY C   111 ( 30 )   11193 - 11198   2007年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We report the enhancement of molecular two-photon absorption (2PA) of a dicationic 2PA chromophore (MPPBT) by confining it in a two-dimensional (2D) nanospace formed in nanolayered silicate clay by the cation exchange method in a water-dimethyl sulfoxide mixture. The 2PA property of the MPPBT/silicate nanocomposite prepared from the mixture by casting is characterized by the femtosecond open-aperture Z-scan method. We found that the 2PA cross-section of the chromophore in the nanocomposite is enhanced by a few times that of the dimethylsulfoxide solution at all wavelengths employed. This enhancement is accompanied by a bathochromic shift of the 2PA peak. The origin of this enhancement is discussed in terms of low dimensionality, suppressed internal twisting motion of the chromophore in the 2D confined space, and ionic interactions with the silicate surfaces.

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  • Void formation in glasses 査読

    Tomohiro Hashimoto, Saulius Juodkazis, Hiroaki Misawa

    NEW JOURNAL OF PHYSICS   9   253   2007年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Void formation as a result of a single tightly focused femtosecond pulse irradiation has been systematically studied in commercial optical-grade glasses of different composition. Correlations between the composition, mass density, glass transition temperature and Young modulus of glass with the void formation threshold have been revealed. The pulse energy necessary to form a void was found reciprocal to the amount of glass-forming oxide in the case of silicate, phosphate and borate glasses. The larger is the bond strength ( the cohesion energy per bond) of the glass-forming oxide, the lower is the threshold energy of the pulse, at which the void is formed after a single pulse irradiation.

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  • Fabrication and properties of metalo-dielectric photonic crystal structures for infrared spectral region 査読

    Vygantas Mizeikis, Saulius Juodkazis, Rima Tarozaite, Jurga Juodkazyte, Kestutis Juodkazis, Hiroaki Misawa

    OPTICS EXPRESS   15 ( 13 )   8454 - 8464   2007年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    We report structural and optical properties of three-dimensional periodic metallic woodpile structures obtained by direct laser writing in dielectric photoresist SU-8 and subsequent electroless coating by a thin Ni film. Signatures of photonic stop gaps were observed in optical reflection spectra of the structures at infrared wavelengths. This study demonstrates that the combination of DLWand chemical infiltration of metals is attractive as a simple and cost-efficient method for the fabrication of metalo-dielectric photonic crystals. (C) 2007 Optical Society of America

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  • Electrophoretic chip for high-fidelity fractionation of double-stranded DNA 査読

    Kai Sun, Zheyu Li, Kosei Ueno, Saulius Juodkazis, Sumihare Noji, Hiroaki Misawa

    ELECTROPHORESIS   28 ( 10 )   1572 - 1578   2007年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    We report the high fidelity on-chip fractionation of selected segrnents, from an electrophoretic flow of separated fragments. dsDNA fragments (10- 330 base pairs were initially separated using a 6.5 cm long channel with an electric field strength of 150 V/cm. As an example of the fractionation process, a target fragment of 20 bp was selected and extracted from the separation channel. The extraction was confirmed and evaluated by fluorescence imaging. High resolution and extraction fidelity were achieved by introducing new. procedures or (i) extraction channel-blocking and (ii) segment transfer with cleaning. These procedures are necessary for the development of a practical, fully automated multitarget fractionation electrophoretic chip. A kind of itCb image processing method was introduced to monitor, control, and evaluate the procedure of fractionation. The resolution limits of the separation and extraction are discussed.

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  • In-bulk and surface structuring of sapphire by femtosecond pulses 査読

    Saulius Juodkazis, Koichi Nishimura, Hiroaki Misawa

    APPLIED SURFACE SCIENCE   253 ( 15 )   6539 - 6544   2007年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The actual space-time dependent intensity distribution of a tightly focused (numerical aperture NA = 1.35) Gaussian femtosecond pulse is modeled inside dielectric material. Such focusing is typically used for recording with sub-wavelength resolution inside dielectrics. The multi-pulse structuring inside the bulk and on the surface of sapphire are demonstrated. Formation of nano-cracks and nano-crystals is revealed inside the crystalline sapphire. Ripple formation on the surface is discussed in terms of the efficacy map calculated by theory given in ref. [J.E. Sipe, IF Young, J.S. Preston, H.M. van Driel, Laser-induced periodic surface structure. I. Theory, Phys. Rev. B 27 (2) (1983) 1141-1154.]. (C) 2007 Published by Elsevier B.V.

    DOI: 10.1016/j.apsusc.2007.01.097

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  • Laser irradiation induced disintegration of a bubble in a glass melt 査読

    S. Juodkazis, N. Murazawa, H. Wakatsuki, H. Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   87 ( 1 )   41 - 45   2007年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    We report on removal of micrometer-sized bubbles from molten glass by a 1064 nm wavelength cw-laser radiation focused using an objective lens of numerical aperture 0.55. The heating of a bubble and surrounding glass by tightly focused laser beam had reduced surface tension and caused disintegration of the bubble. Disintegration occurred at typically 1850 +/- 50 50 degrees C. Emission of a heated gas inside the bubble was used to determine the local temperature. Temporal evolution of the bubble disintegration was imaged by a CCD camera. Physics of the interaction between a focused laser beam and bubble is discussed.

    DOI: 10.1007/s00339-006-3848-x

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  • Spectral sensitivity of uniform arrays of gold nanorods to dielectric environment 査読

    Kosei Ueno, Saulius Juodkazis, Masahiro Mino, Vygantas Mizeikis, Hiroaki Misawa

    JOURNAL OF PHYSICAL CHEMISTRY C   111 ( 11 )   4180 - 4184   2007年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Uniform, ordered arrays of gold nanorods on glass substrates were fabricated with high accuracy using electron beam lithography and lift-off techniques. These structures exhibit longitudinal mode of localized surface plasmon (LSP) resonance with spectral position highly sensitive to the refractive index of local dielectric environment of the nanorods. The LSP resonance was found to red-shift nearly linearly, both with refractive index and aspect ratio of the nanorods, to the extent that enables optical detection of the refractive index changes of the order of 10(-2). The entire spectral range of the detection can be defined by tailoring size and aspect ratio of the nanorods during the fabrication and typically falls into the optical communications region. These structures are therefore promising as optical sensors enabling simple and efficient monitoring of chemical and biological processes.

    DOI: 10.1021/jp068243m

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  • Structural characterization of shock-affected sapphire 査読

    M. Mazilu, S. Juodkazis, T. Ebisui, S. Matsuo, H. Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   86 ( 2 )   197 - 200   2007年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    The presence of dislocations has been revealed by numerical processing of high-resolution transmission electron microscopy images from the regions affected by a shock wave propagation. The shock wave was triggered by a single 220 fs duration pulse of 30 nJ at an 800 nm wavelength inside sapphire at approximately 10 mu m depth. The shock-amorphised sapphire has a distinct boundary with the crystalline phase, which is not wet etchable even at a dislocation density of similar or equal to 8 x 10(12) cm(-2).

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  • Formation of nano-fibers and micro-spheres by femtosecond laser ablation of chalcogenide glass 査読

    O. A. Louchev, S. Juodkazis, H. Misawa, K. Kitamura

    INTERNATIONAL CONFERENCE ON LASERS, APPLICATIONS, AND TECHNOLOGIES 2007: LASER-ASSISTED MICRO- AND NANOTECHNOLOGIES   6732   2007年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    Formation of nano-fibers ranging from 30 to 300 nm in diameter and exceeding the length of one millimeter was observed during explosive ablation of As2S3 glass by femtosecond pulses at high fluence (&gt; 5 J/cm(2)) irradiation of the 800 nm wavelength, 160 fs duration pulses in air. However, the spheres of up to several microns in diameter are found to form competing with nano-fiber formation and significantly deteriorating their morphology. The formation of these pheres is explained by the free energy minimization of explosively ablating liquid jets combined with the onset and evolution of the thermo-capillary forces at the local perturbations of the geometry and temperature. Performed thermal analysis suggests that the good nano-fiber morphology can be preserved by increasing the air pressure or ablation in water which shortens the characteristic cooling and solidification time of the liquid jets, and inhibits the development of the small geometrical perturbations into the large spheres.

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  • Multi-megabar pressure and super-dense materials created by laser-induced micro-explosion inside of transparent solid 査読

    Saulius Juodkazis, Hiroaki Misawa, Eugene G. Gamaly, Barry Luther-Davies, Andrei V. Rode, Ludovic Hallo, Phillipe Nicolai, Vladimir T. Tikhonchuk

    SHOCK COMPRESSION OF CONDENSED MATTER - 2007, PTS 1 AND 2   955   1041 - +   2007年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    Extremely high pressure (similar to 10 TPa) and temperature (5 X 10(5) K) have been produced using a single laser pulse (similar to 100 nJ, 800 nm, 200 fs) focused inside transparent dielectrics. The laser pulse of intensity over 0.1 PW/cm(2) converts a material within the absorption volume of similar to 0.15 mu m(3) into plasma in a few fenitoseconds. A pressure of similar to 10 TPa, far exceeding the strength of any material builds up to the end of the pulse generating strong shock and rarefaction waves. This results in the formation of a nano-void surrounded by a shell of shock-compressed material. In sapphire, the compressed shell revealed that it has a density 1.14 times of the initial one and increased chemical reactivity. The unique conditions: extreme pressure and temperature at record high heating and cooling rates become available in a well-controlled laboratory environment.

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  • Three-dimensional laser microfabrication of metals, semiconductors, and dielectrics 査読

    Saulius Juodkazis, Koichi Nishimura, Hiroki Okuno, Yusuke Tabuchi, Shigeki Matsuo, Satoru Tanaka, Hiroaki Misawa

    INTERNATIONAL CONFERENCE ON LASERS, APPLICATIONS, AND TECHNOLOGIES 2007: LASER-ASSISTED MICRO- AND NANOTECHNOLOGIES   6732   67320B/1-10   2007年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    We demonstrate three - dimensional (3D) structuring of materials by femtosecond laser irradiation. The self-organized ordered formation of ripples by a laser raster-scanning on the surface of 4H-SiC is demonstrated. This method is scalable up to areas with sum-millimeter cross-sections. The role of ripple-like structures in the case of the surface and in-bulk micro-structuring of different materials is discussed. The field enhancement effects at the nano-structured surfaces and their role in ripple formation are estimated.

    DOI: 10.1117/12.751889

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  • Femtosecond laser structuring of As2S3 glass for erasable and permanent optical memory 査読

    Saulius Juodkazis, Andrei V. Rode, Toshiaki Kondo, Hiroaki Misawa, Marek Samoc, Barry Luther-Davies

    MATERIALS AND PROCESSES FOR NONVOLATILE MEMORIES II   997   357 - +   2007年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:MATERIALS RESEARCH SOC  

    The nonlinear absorption coefficient of As2S3 glass has been measured to be 2.0 cm/GW for femtosecond pulses at 800 nm. Femtosecond laser structuring via two photon absorption in bulk As2S3 glass by erasable and permanent photo-darkening is demonstrated using both holographic and direct multi-beam laser writing.

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  • Three-dimensional Laser Structuring of Materials at Tight Focusing 査読

    S. Juodkazis, K. Nishimura, H. Misawa

    Chinese Opt. Lett.   5   S198 - S200   2007年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Optical characterization of plasmonic metallic nanostructures fabricated by high-resolution lithography 査読

    Yukie Yokota, Kosei Ueno, Vygantas Mizeikis, Saulius Juodkazis, Keiji Sasaki, Hiroaki Misawa

    JOURNAL OF NANOPHOTONICS   1   011594/1-15   2007年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS  

    Highly homogeneous arrays of Ag, Au and Cu nanorods were fabricated on glass substrates using electron-beam lithography and lift-off techniques. Optical properties of the fabricated structures related to localized surface plasmons (LSP), and their dependencies on the nanorod size were studied experimentally by optical extinction spectroscopy. Spectral tuning of LSP resonant scattering bands in a wide spectral range, from visible to near-infrared wavelengths, can be accomplished by tailoring of the nanorod dimensions, aspect ratios, and heights. The observed results qualitatively agree with Gans theory and numerical modeling by finite-difference time-domain technique.

    DOI: 10.1117/1.2832749

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  • Simulation of Light Interaction with Metallic Nanoparticles 査読

    Saulius Juodkazis, Hiroaki Misawa, Egidijus Vanagas, Mingwei Li

    JOURNAL OF LASER MICRO NANOENGINEERING   1 ( 3 )   253 - 257   2006年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN LASER PROCESSING SOC  

    A high-precision 3D structuring of dielectrics by sub-1 ps pulses is possible by dielectric breakdown and opens an unique possibility to create a high temperature electrons inside material under processing. The 3D nano/micro-structuring by dielectric breakdown is numerically simulated by 3D finite-differences time domain (FDTD) calculations where the plasma is simulated by a nano-sphere of metal (gold). The effect of anisotropic light scattering in the plane of incident polarization has been qualitatively explained by light inteaction with ionized (metalic) focal volume. It is shown that the experimentaly achieved densification of materials after irradiation by tightly focused sub-1 ps pulses is consistent with formation of new high-pressure phases.

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  • Spectrally-resolved atomic-scale length variations of gold nanorods 査読

    Kosei Ueno, Saulius Juodkazis, Vygantas Mizeikis, Keiji Sasaki, Hiroaki Misawa

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   128 ( 44 )   14226 - 14227   2006年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    DOI: 10.1021/ja0645786

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  • Raman microspectroscopy/imaging study on phase-vanishing processes of fluorous biphase systems in microchannel-microheater chips 査読

    Takeshi Araki, Kousei Ueno, Hiroaki Misawa, Noboru Kitamura

    ANALYTICAL SCIENCES   22 ( 10 )   1283 - 1289   2006年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC ANALYTICAL CHEMISTRY  

    Temperature-dependent phase-vanishing processes between perfluorohexane (FC-72) and n-heptane (C7H16, volume ratio of 1:1 and phase-vanishing temperature &gt;41 degrees C), were studied in a glass microchannel-microheater chip under solution-flow conditions. Without applying a voltage to the heater at 21 C, the two liquids in the microchannel were separated into two streams at a solution flow rate (v) of 0.975 cm/s, while the phase boundary between FC-72 and C7H16 vanished in the downstream side of the heater at V = 4.5 V. Then, we conducted Raman intensity imaging during the phase vanishing processes in the microchannel by monitoring the band at 756 (FC-72) or 1456 cm(-1) (C7H16). At V = 4.5 V and v = 0.975 cm/s, although no phase boundary between the two liquids in the microchannel was observed, the relevant Raman intensity images indicated the inhomogeneous nature of the solution, and distribution of C7H16 to the FC-72 phase along with solution flow was observed.

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  • Femtosecond laser ablation of chalcogenide glass: explosive formation of nano-fibres against thermo-capillary growth of micro-spheres 査読

    Saulius Juodkazis, Hiroaki Misawa, Oleg A. Louchev, Kenji Kitamura

    NANOTECHNOLOGY   17 ( 19 )   4802 - 4805   2006年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Formation of nano-fibres ranging from 30 to 300 nm in diameter and exceeding the length of one millimetre was observed during explosive ablation of As2S3 glass by femtosecond pulses at high fluence (&gt; 5 J cm(-2)) irradiation of the 800 nm wavelength, 160 fs duration pulses in air. Spheres of up to several microns in diameter were also found to form, competing with nano-fibre formation and significantly deteriorating their morphology. Theoretical analysis of thermo-capillary and heat exchange mechanisms of the fibre formation predicts conditions under which the good nano-fibre morphology can be preserved.

    DOI: 10.1088/0957-4484/17/19/003

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  • Fabrication of three-dimensional periodic microstructures in photoresist SU-8 by phase-controlled holographic lithography 査読

    Toshiaki Kondo, Saulius Juodkazis, Vygantas Mizeikis, Shigeki Matsuo, Hiroaki Misawa

    NEW JOURNAL OF PHYSICS   8 ( 250 )   2006年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Three-dimensional (3D) periodic dielectric structures were recorded in a commercial photoresist SU-8 by exposure to intensity patterns created by five interfering coherent femtosecond Ti : sapphire laser pulses. Periodic symmetry of these patterns was controlled by the choice of mutual convergence angles of the beams as well as their phases. The fabricated structures are mechanically and chemically stable, well-connected frameworks of SU-8 regions in air; the smallest dimensions of SU-8 features are in the sub-micrometre range. The structures exhibit a high degree of long-range order across areas as large as 1 mm in cross-section.

    DOI: 10.1088/1367-2630/8/10/250

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  • Laser manipulation of a smectic liquid-crystal droplet 査読

    N. Murazawa, S. Juodkazis, H. Misawa

    EUROPEAN PHYSICAL JOURNAL E   20 ( 4 )   435 - 439   2006年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    The laser trapping of a smectic-A liquid-crystal micro-droplet was spatially traced during its transient into the trapped position. The lateral and angular orientation of the droplet were determined and followed in time during the axial descent of the micro-droplet into the stationary trapped position using the analysis of polarization changes of the light passed through the droplet with temporal resolution of a video refresh rate of 30 ms. The spatial resolution of 0.1-1 mu m has been achieved for typical laser trapping powers of 2-600 mW. The axial profile of a laser trapping force (an ellipticity of the focal spot) has been determined. The laser trapping mechanism of smectic micro-droplets is discussed in terms of minimization of a light-droplet interaction.

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  • Three-dimensional recording by tightly focused femtosecond pulses in LiNbO3 査読

    Saulius Juodkazis, Markas Sudzius, Vygantas Mizeikis, Hiroaki Misawa, Eugene G. Gamaly, Youwen Liu, Oleg A. Louchev, Kenji Kitamura

    APPLIED PHYSICS LETTERS   89 ( 6 )   062903   2006年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    The authors report on a three-dimensional single-shot optical recording by 150 fs pulses at 800 nm wavelength in Fe doped LiNbO3. The rewritable bits (2(x)x2(y)x8(z) mu m(3)) are demonstrated. The highest refractive index modulation of similar to 10(-3) per single pulse has been formed by preferential photovoltaic effect at close to the dielectric breakdown irradiance of similar to TW/cm(2) and was independent of polarization (in respect to the c axis). The achievable refractive index modulation is evaluated and the recording mechanisms are discussed. (c) 2006 American Institute of Physics.

    DOI: 10.1063/1.2335364

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  • Holographic lithography of periodic two- and three-dimensional microstructures in photoresist SU-8 査読

    Toshiaki Kondo, Saulius Juodkazis, Vygantas Mizeikis, Hiroaki Misawa, Shigeki Matsuo

    OPTICS EXPRESS   14 ( 17 )   7943 - 7953   2006年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    Micro-fabrication of periodic structures was performed by holographic lithography technique in SU-8 photoresist using a simple and versatile experimental arrangement based on a diffractive beam-splitter. High-fidelity two-and three-dimensional microstructures fabricated with sub-micrometric resolution in large areas of approximately 1 mm diameter. The structures are potentially usable as elements of micro-fluidic systems (e. g., Brownian ratchets), and templates for photonic crystal devices (e. g., mirrors, collimators, superprisms).

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  • Photo-structuring of As2S3 glass by femtosecond irradiation 査読

    Saulius Juodkazis, Toshiaki Kondo, Hiroaki Misawa, Andrei Rode, Marek Samoc, Barry Luther-Davies

    OPTICS EXPRESS   14 ( 17 )   7751 - 7756   2006年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    The nonlinear absorption coefficient of As2S3 glass has been measured to be 2.0 cm/GW for femtosecond pulses at 800 nm. Femtosecond laser structuring via two photon absorption in bulk As2S3 glass by erasable and permanent photo-darkening is demonstrated using both holographic and direct multi-beam laser writing. (c) 2006 Optical Society of America.

    DOI: 10.1364/OE.14.007751

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  • Feature-size reduction of photopolymerized structures by femtosecond optical curing of SU-8 査読

    Kock Khuen Seet, Saulius Juodkazis, Vygandas Jarutis, Hiroaki Misawa

    APPLIED PHYSICS LETTERS   89 ( 2 )   024106-1 - 024106-3   2006年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    The universal scaling of a width of photopolymerized line on the exposure dose was observed in polymerization by direct laser writing using tightly focused femtosecond pulses in SU-8 resist. This scaling can be explained as the photopolymerization by a blackbody-type emission. A spectrally broad thermal emission of electrons heated up to temperatures approximately T-e similar to 10(3) K coincides with an IR-absorption band of SU-8 centered at the 2.9 mu m and had caused polymerization by a cumulative direct absorption. Three-dimensional photonic crystal templates with approximately twice reduced feature size were fabricated with stop band at the fiber communication wavelength of 1.3 mu m. (c) 2006 American Institute of Physics.

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  • Three-dimensional circular spiral photonic crystal structures recorded by femtosecond pulses 査読

    Kock Khuen Seet, Vygantas Mizeikis, Saulius Juodkazis, Hiroaki Misawa

    JOURNAL OF NON-CRYSTALLINE SOLIDS   352 ( 23-25 )   2390 - 2394   2006年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Photonic crystal structures having three-dimensional (3D) circular spiral architecture have large theoretical photonic band-gap but cannot be implemented by most of the existing microfabrication techniques. We have successfully used a highly versatile 3D microstructuring technique called femtosecond laser microfabrication to prepare templates of the circular spiral photonic crystals in a commercially available photoresist SU-8. The structures fabricated have good structural quality, are highly periodic and exhibit spectral signatures of photonic bands dispersion in the short infrared wavelength region. (c) 2006 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jnoncrysol.2006.02.079

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  • Femtosecond laser assisted etching of quartz: microstructuring from inside 査読

    S Matsuo, Y Tabuchi, T Okada, S Juodkazis, H Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   84 ( 1-2 )   99 - 102   2006年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    In quartz crystal substrates, microchannels were made by femtosecond laser assisted etching, i.e., irradiation of focused femtosecond laser pulses followed by wet etching. By the use of wet etching, the laser irradiated region was selectively etched out, and a microchannel was formed inside the quartz substrate. The laser irradiated region was found to be amorphous by transmission electron microscopy. Anisotropy in the etching rate inside the quartz was observed.

    DOI: 10.1007/s00339-006-3603-3

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  • (Some) Future Trends 査読

    Saulius Juodkazis, Hiroaki Misawa

    3D Laser Microfabrication: Principles and Applications   379 - 385   2006年6月

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    記述言語:英語   掲載種別:論文集(書籍)内論文   出版者・発行元:Wiley-VCH Verlag GmbH &amp; Co. KGaA  

    DOI: 10.1002/352760846X.ch13

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  • Laser-matter interaction in the bulk of a transparent solid: Confined microexplosion and void formation 査読

    EG Gamaly, S Juodkazis, K Nishimura, H Misawa, B Luther-Davies

    PHYSICAL REVIEW B   73 ( 21 )   214101   2006年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    We present here the experimental and theoretical studies of a single femtosecond laser pulse interaction inside a bulk of transparent media (sapphire, glass, polymer). This interaction leads to the drastic transformations in a solid resulting in a void formation inside a dielectric. The laser pulse energy is absorbed within a volume of approximately 0.15 mu m(3) creating a pressure and temperature comparable to that in the core of a strong multi-kilo-tons explosion. The material within this volume is rapidly atomized, ionized, and converted into a tiny super-hot dense cloud of expanding plasma that generates strong shock and rarefaction waves which result in the formation of a void, whose diameter is similar to 200 nm (for a 100 nJ pulse in sapphire). The way this structure forms can be understood from high-temperature plasma hydrodynamics. We demonstrate that unique states of matter characterized by temperatures similar to 10(5) K, heating rates up to the 10(18) K/s, and pressures more than 100 times the strength of any material were created using a standard table-top laser in well-controlled laboratory conditions. We discuss the properties of the laser-affected solid and possible routes of laser-affected material transformation to the final state long after the pulse end. These studies will find application for the design of new materials and three-dimensional optical memory devices, and for formation of photonic band-gap crystals.

    DOI: 10.1103/PhysRevB.73.214101

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  • Control over the crystalline state of sapphire 査読

    S Juodkazis, K Nishimura, H Misawa, T Ebisui, R Waki, S Matsuo, T Okada

    ADVANCED MATERIALS   18 ( 11 )   1361 - +   2006年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    Amorphous regions in sapphire with sub-micrometer 3D resolution have been produced at the focus of a single femtosecond laser pulse. Crystalline-to-amorphous and amorphous-to-polycrystalline transitions (crystalline and amorphous regions are marked C and A in the HRTEM image) are induced by single- and multi-pulse irradiation, respectively. The wet-etching selectivity for the amorphous phase is significantly greater than that for the crystalline phase in aqueous HF.

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  • Top-gathering pillar array of hybrid organic-inorganic material by means of self-organization 査読

    H. Segawa, S. Yamaguchi, Y. Yamazaki, T. Yano, S. Shibata, H. Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   83 ( 3 )   447 - 451   2006年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Two-dimensional (2D) pillar arrays with submicrometer to micrometer repetitions have been fabricated from hybrid organic-inorganic material by mask lithography or multi-beam interference lithography. The type of array structure depends on structural parameters such as the pillar height, diameter and distance between neighboring pillars. Two kinds of periodic arrays, 2D arrays and 'top-gathering' arrays, can be obtained by controlling the structural parameters. In the top-gathering arrays, the pillars are gathered at the top by means of self-organization, and 'top-gathering' units composed of four pillars can be formed.

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  • Three-dimensional Horizontal Circular Spiral Photonic Crystals with Stop Gaps below 1 μm 査読

    K. K. Seet, V. Mizeikis, S. Juodkazis, H. Misawa

    Appl. Phys. Lett.   88 ( 22 )   221101   2006年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Void recording in silica 査読

    T Hashimoto, S Juodkazis, H Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   83 ( 2 )   337 - 340   2006年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    We report on the formation of voids of 200-300 nm in diameter by single femtosecond pulses (800 nm/150 fs/ &lt; 100 nJ) inside silica glass. The mechanism of void formation can be understood in terms of dielectric breakdown and shock wave formation. The voids were recorded below the threshold of self-focusing. Diffraction efficiency of gratings recorded by arranging voids into a pattern of open core channels have shown an interesting tendency of an increasing efficiency for the first five diffraction orders. It is demonstrated by numerical simulation using the finite difference time domain (FDTD) algorithm that such anomalous diffraction is indeed caused by empty core channels surrounded by densified shells inside silica.

    DOI: 10.1007/s00339-006-3501-8

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  • Laser-induced microexplosion confined in a bulk of silica: Formation of nanovoids 査読

    S Juodkazis, H Misawa, T Hashimoto, EG Gamaly, B Luther-Davies

    APPLIED PHYSICS LETTERS   88 ( 20 )   201909   2006年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    We report on the nanovoid formation inside synthetic silica, viosil, by single femtosecond pulses of 30-100 nJ energy, 800 nm wavelength, and 180 fs duration. It is demonstrated that the void is formed as a result of shock and rarefaction waves at pulse power much lower than the threshold of self-focusing. The shock-compressed region around the nanovoid is demonstrated to have higher chemical reactivity. This was used to reveal the extent of the shock-compressed region by wet etching. Application potential of nanostructuring of dielectrics is discussed. (c) 2006 American Institute of Physics.

    DOI: 10.1063/1.2204847

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  • Laser-induced microexplosion confined in the bulk of a sapphire crystal: Evidence of multimegabar pressures 査読

    S Juodkazis, K Nishimura, S Tanaka, H Misawa, EG Gamaly, B Luther-Davies, L Hallo, P Nicolai, VT Tikhonchuk

    PHYSICAL REVIEW LETTERS   96 ( 16 )   166101   2006年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    Extremely high pressures (similar to 10 TPa) and temperatures (5x10(5) K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 10(14) W/cm(2) converting material within the absorbing volume of similar to 0.2 mu m(3) into plasma in a few fs. A pressure of similar to 10 TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 10(18) K/s can, thus, be studied in a well-controlled laboratory environment.

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  • Three-dimensional optical recording in tert-butoxycarbonyl-protected quinizarin methacrylate polymers 査読

    T Mizuno, Y Tanamura, K Yamasaki, H Misawa

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   45 ( 3A )   1640 - 1647   2006年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC APPLIED PHYSICS  

    We report photoacid-induced nonerasable recording in tert-butoxycarbonyl-protected quinizarin methacrylate polymers for three-dimensional optical memory. 1 m/s-speed recording was achieved using an 800nm femtosecond laser at an 80MHz-repetition rate, without a postexposure bake after laser irradiation. Three-layer recording indicates that no optical damage during recording enables modulation of the Compact Disc type memory. The linewidth of recorded marks of 0.4 mu m indicates a 49 Gbits/cm(2) areal density when the numerical aperture is 1.35.

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  • Laser manipulation based on a light-induced molecular reordering 査読

    N Murazawa, S Juodkazis, H Misawa

    OPTICS EXPRESS   14 ( 6 )   2481 - 2486   2006年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    We report on a novel principle of actuation of micrometer-sized liquid crystal droplets. It is based on a light-induced reordering of liquid crystal molecules inside the droplets. Polariscope imaging allowed to evaluate the birefringence change inside the micro-droplets. Directional actuation of the trapped droplet was achieved by cycling laser power with the direction defined by the polarization of the tweezing beam. Micro-actuation resulted from optically-induced birefringence; i.e., a nonlinear optical effect was utilized for mechanical manipulation of the micro-droplet. This principle of actuation can be used to induce molecular flows in sub-micrometer volumes. (c) 2006 Optical Society of America.

    DOI: 10.1364/OE.14.002481

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  • Spiral three-dimensional photonic crystals for telecommunications spectral range 査読

    KK Seet, Mizeikis, V, S Juodkazis, H Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   82 ( 4 )   683 - 688   2006年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Three-dimensional photonic crystals consisting of periodic arrays of spiral columns were fabricated in a commercially available photoresist (SU-8) by a direct laser writing technique. Tailoring the pre- and post-processing conditions for the photoresist has enabled the recording of extended, self-supporting periodic structures with sub-diffraction resolution. Pronounced photonic stop gaps were observed at wavelengths between 1.5 and 1.8 mu m, close to the telecommunications region. These structures can be used as accurate and robust templates for subsequent infiltration by materials with higher refractive index.

    DOI: 10.1007/s00339-005-3459-y

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  • Viscosity measurement using a rotating laser-trapped microsphere of liquid crystal 査読

    N Murazawa, S Juodkazis, Jarutis, V, Y Tanamura, H Misawa

    EUROPHYSICS LETTERS   73 ( 5 )   800 - 805   2006年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:EDP SCIENCES S A  

    We demonstrate that the viscosity measurement by a spinning laser-trapped liquid-crystal microsphere depends on the surface tension and hydrophobicity of sphere's material. A reduction of the viscous drag was observed for the hydrophobic E44 liquid-crystal droplets even at low surface tension, while a reduced surface tension caused an increased drag in the case of 5CB microspheres. The importance of the non-slipping boundary condition and light propagation throughout the laser-trapped microsphere in the viscosity measurements by a spinning microsphere (Bishop A. I. et al., Phys. Rev. Lett., 92 (2004) 198104) is discussed.

    DOI: 10.1209/epl/i2005-10457-7

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  • Rheology measurement at liquid-crystal water interface using laser tweezers 査読

    N Murazawa, S Juodkazis, Y Tanamura, H Misawa

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   45 ( 2A )   977 - 982   2006年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INST PURE APPLIED PHYSICS  

    We demonstrated that viscosity measurement using a spinning laser-trapped microsphere depends on the hydrophobicity or hydrophylicity of a spherical material. Reduction in viscous drag was observed in hydrophobic liquid crystal droplets. Rheology on a liquid crystal surface with D2O was demonstrated by spinning and stopping a laser tweezed droplet. The importance of nonslipping boundary conditions in viscosity measurements is discussed.

    DOI: 10.1143/JJAP.45.977

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  • Optical third harmonic generation during femtosecond pulse diffraction in a Bragg grating 査読

    S Juodkazis, E Gaizauskas, Jarutis, V, J Reif, S Matsuo, H Misawa

    JOURNAL OF PHYSICS D-APPLIED PHYSICS   39 ( 1 )   50 - 53   2006年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We report on a novel phenomenon occurring when ultrashort laser pulses are diffracted in a Bragg grating recorded in a photo-thermo-refractive glass: two intense beams at the third harmonic of the incident laser frequency appear between the direct and the diffracted laser beams. A high conversion efficiency of about 0.04% at an incident intensity of 5 x 10(11) W cm(-2) in a 1 mm thick grating is attributed to self-phase matching for the third harmonic generation via Cherenkov radiation from the interfering third order polarization of the incident and diffracted beams. It is assumed that this is a general phenomenon for diffraction in a volume grating.

    DOI: 10.1088/0022-3727/39/1/009

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  • Discrete damage traces from filamentation of Gauss-Bessel pulses 査読

    E Gaizauskas, E Vanagas, Jarutis, V, S Juodkazis, Mizeikis, V, H Misawa

    OPTICS LETTERS   31 ( 1 )   80 - 82   2006年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    Filamentation of Bessel-Gauss pulses propagating in borosilicate glass is found to produce damage lines extending over hundreds of micrometers and consisting of discrete, equidistant damage spots. These discrete damage traces are explained by self-regeneration of Gauss-Bessel beams during propagation and are potentially applicable in laser microfabrication of transparent materials. (c) 2006 Optical Society of America.

    DOI: 10.1364/OL.31.000080

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  • Femtosecond laser microfabrication of 3D photonic structures 査読

    Kock Khuen Seet, Toshiaki Kondo, Vygantas Mizeikis, Vygandas Jarutis, Saulius Juodkazis, Hiroaki Misawa

    Proceedings of SPIE - The International Society for Optical Engineering   6161   2006年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    The physical principles underlying the three-dimensional (3D) laser microstructuring technique are outlined, its applications for the fabrication of 3D photonic crystals are described. Structures recorded by direct laser writing and holographic recording techniques in SU-8 photoresist are presented along with their structural and optical characterization.

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  • Laser manipulation and characterization of liquid crystal droplets 査読

    Naoki Murazawa, Saulius Juodkazis, Hiroaki Misawa

    OPTICAL TRAPPING AND OPTICAL MICROMANIPULATION III   6326   1 - 9   2006年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    We demonstrate laser manipulation of different nematic and smectic liquid crystal droplets in heavy water. Peculiarities of laser trapping and manipulation depending on the molecular structure of liquid crystal are discussed. Possibility of molecular reordering inside the tweezed droplet is demonstrated. This phenomenon can be used to induce the birefringence and to manipulate droplets, which have a small birefringence, e.g., a radial droplet of negligible birefringence can be turned into a birefringent one at high laser trapping power. This is a demonstration of the optical nonlinear effect being responsible for a micro-mechanical phenomenon such as spinning of the droplet in a circularly polarized laser tweezers. Three-photon absorption of MBAPB dye at 1064 nm wavelength is demonstrated inside the liquid crystal droplet at comparatively low similar to 60 MW/cm(2) intensity.

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  • Three-dimensional laser microfabrication 査読

    Saulius Juodkazis, Hiroaki Misawa

    FEMTOSECOND PHENOMENA AND NONLINEAR OPTICS III   6400   1 - 8   2006年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    The mechanism of three-dimensional (3D) laser micro-structuring of dielectrics (resists, polymers, glasses, and crystals) by the direct laser writing is discussed. Overview of a light-matter interaction of a tightly-focused femtosecond pulse with dielectrics is presented. The void formation is demonstrated inside silica glass by a single picosecond pulse. Peculiarities of tight focusing and an axial superposition of two co-propagating pulses at the focus are revealed by numerical simulations. Potential of the fabricated 3D patterns in micro-photonics, micro-fluidics, and sensor applications is discussed.

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  • Studies of femtosecond pulse filamentation in glasses 査読

    S Juodkazis, Mizeikis, V, E Gaizauskas, E Vanagas, Jarutis, V, H Misawa

    INTERNATIONAL CONFERENCE ON LASERS, APPLICATIONS, AND TECHNOLOGIES 2005: HIGH-POWER LASERS AND APPLICATIONS   6053   2006年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    Self-focusing and filamentation of nearly-Gaussian femtosecond laser pulses propagating in photosensitive silicate glass was investigated. The filamentation was visualized by the precipitation of NaF nano-crystallites along the beam pass after post-exposure treatment of photosensitive glass, which provides a direct proof that ionization of silicate matrix takes place along the filament propagation lines. Theoretical model of the multi-filamentation based on the propagation of a Gaussian beam with elliptical transverse intensity profile modulated by a spatial noise in a medium with multi-photon absorption is proposed.
    Self-action of the ferntosecond Gaussian-Bessel pulses in borosilicate glass was observed at high fluence. This model reproduces qualitatively the dotted damage lines observed after the beam propagation in borosilicate glass.

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  • Thermal effects in three-dimensional recording by femto/nano-second pulses 査読

    Sauhus Juodkazis, Mingwei Li, Dmitry Kotin, Igor Maksimov, Egidijus Vanagas, Hiroaki Misawa

    ULTRAFAST PHENOMENA IN SEMICONDUCTORS AND NANOSTRUCTURE MATERIALS X   6118   2006年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    Thermal effects are unavoidable in laser material processing and are present, to some extent, even in the case when ultra-short (sub-picosecond) pulsed irradiation is used. We discuss here the matters of high-precision energy delivery into micrometer-sized volumes for three-dimensional (3D) laser microfabrication. Precise account of the absorbed energy, pulse duration, and focal spot size allows to optimize laser processing parameters. As an example, a 3D micro-structuring of silica with better than 15 mu m resolution is demonstrated by pulses of 11 ns duration and 266 nm wavelength (for a focusing by a low numerical aperture NA = 0.029 lens). The two photon absorption coefficient of silica, beta similar or equal to 60 +/- 10 cm/GW, at 266 nm has been determined.
    The thermal black-body type emission of non-equilibrated electrons is discussed as a possible light source for 3D modification and structuring of photo-sensitive and photo-polymerizable materials. It is also demonstrated that optical properties of ionized dielectrics can be used to determine the temperature.

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  • Fabrication of periodic Arrays of top-gathering Titania-organic hybrid pillars derived from multi-beam laser interference 査読

    Hiroyo Segawa, Hiroaki Misawa, Tetsuji Yano, Shuichi Shibata

    PHOTON PROCESSING IN MICROELECTRONIC AND PHOTONICS V   6106   2006年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    Multi-beam laser interference (MLI) lithography is known to be one of the fabrication techniques of photonic crystals. In MLI lithography laser beams are interfered on a scale of the wavelength of light and are irradiated to photosensitive films. We have paid attention to photosensitive TiO2-organic hybrid film, which has high refractive index. TiO2-organic hybrid periodic pillar patterns were fabricated by MLI lithography. The TiO2) hybrid film, which was prepared from Ti-alkoxide and beta-diketone by the sol-gel method, was exposed to the interference pattern of femtosecond pulses at 800 run wavelength. After laser irradiation, the unirradated portion was removed by the development and rinse. Two-dimensional periodic standing alone pillars and 2 x 2 and 3 x 3 top-gathering pillars, which were gathered at the top by means of self-organization were formed by changing conditions such as laser irradiation time and film thickness. The pillar patterns depended upon the rinse liquid, the diameter, and the height of pillars. The top-gathering pillars are applicable for diffractive optics.

    DOI: 10.1117/12.647213

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  • Reduction of capillary force for high-aspect ratio nanofabrication 査読

    T Kondo, S Juodkazis, H Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   81 ( 8 )   1583 - 1586   2005年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    The wet processing of SU8 resist was modified in order to achieve a high-aspect ratio patterning with feature size of 100 nm. A final rinse in water, which makes a large contact angle on the resist (less wetting) was added to the procedure. This allowed considerable reduction of the capillary force, which is responsible for pattern distortions in three-dimensional (3D) lithography. 3D recording of high-aspect ratio (f(ar)=18) structures by holographic exposure using femtosecond pulses in SU8 resist was achieved using this modified development procedure. The thickness of the free-standing planes was approximately 100 nm. High fidelity of this recording method was confirmed by a Moire pattern transfer into a developed SU8 pattern. In terms of focusing, the 100 nm feature size comprised 1/13-th of the diffraction limit. This modified development is applicable for wet processing when super-critical drying cannot be used.

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  • Three-dimensional optical memory in a photoacid-induced recording medium 査読

    T Mizuno, K Yamasaki, H Misawa

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   44 ( 9A )   6593 - 6595   2005年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN SOC APPLIED PHYSICS  

    We report a photoacid-induced write-once read-many recording medium based on poly(methyl methacrylate) for three dimensional (3D) optical memory, Three-layered recording was achieved using only an 800 nm-femtosecond oscillator with a 82-MHz-repetition rate without structural damage. Bits of arbitrary length used in the present modulation method of Compact Disc type memory can be recorded by photo-modification in the medium. The results suggest that the medium is an attractive candidate to solve the technical problems of 3D recording, in which micro-structural integrity of medium is altered.

    DOI: 10.1143/JJAP.44.6593

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  • Analysis of stress induced by a three-dimensional recording in glass 査読

    E Vanagas, JY Ye, M Li, M Miwa, S Juodkazis, H Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   81 ( 4 )   725 - 727   2005年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Stress/strain around the line recorded inside borosilicate glass was investigated by polarization microscopy. Thermal accumulation effects were observed during in-bulk recording. The relevance of the phenomena for laser scribing and dicing applications is discussed.

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  • Comparison of the classical rate and the Einstein coefficient for spontaneous emission in a light-absorbing cavity 査読

    VV Datsyuk, S Juodkazis, H Misawa

    PHYSICAL REVIEW A   72 ( 2 )   025803   2005年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    The rate of spontaneous electromagnetic emission in a cavity is the normalized output radiation rate in the classical electrodynamics and the Einstein A coefficient in a quantum theory. We reveal the difference and similarity between the quantum and classical rates by calculations of the relative output power of the resonant spontaneous electric-dipole emission as a function of light absorption in a high-Q cavity. We show that the relative resonant output power is equal to the relative width of a morphology-dependent resonance in the spectral dependence of the Einstein A coefficient. The validity of the theory is demonstrated by numerical verification of an experimental result on a microsphere.

    DOI: 10.1103/PhysRevA.72.025803

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  • Characterization of bipolar and radial nematic liquid crystal droplets using laser-tweezers 査読

    N Murazawa, S Juodkazis, H Misawa

    JOURNAL OF PHYSICS D-APPLIED PHYSICS   38 ( 16 )   2923 - 2927   2005年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Bipolar and radial droplets of 4-pentyl-4'-cyanobiphenyl were manipulated using circularly polarized laser-tweezers. Light-induced birefringence arising from orientational nonlinearity was observed and measured for the radial droplets. The highest laser trapping power used 0.5 W induced a birefringence of 0.02 and hence the spinning of the droplets was observed.

    DOI: 10.1088/0022-3727/38/16/027

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  • Optical properties of nanoengineered gold blocks 査読

    K Ueno, Mizeikis, V, S Juodkazis, K Sasaki, H Misawa

    OPTICS LETTERS   30 ( 16 )   2158 - 2160   2005年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    We report on control over the extinction spectrum of tetragonal gold nanoblocks by changing their lateral aspect ratio. Nanoblocks were patterned on a glass substrate by electron-beam lithography and were 40-400 mn in lateral dimensions and spanned from 1 to 9 in aspect ratio. This allowed us to tune the localized surface plasmon bands from 700 nm to 1.5 mu m (longitudinal mode) and from 700 to 550 mu m (transverse mode). Unprecedented polarization selectivity of the transverse and longitudinal plasmon bands was achieved via alignment and 3D control of the dimensions of the nanoblocks. (c) 2005 Optical Society of America.

    DOI: 10.1364/OL.30.002158

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  • Properties of a laser based on evanescent-wave amplification 査読

    VV Datsuyk, S Juodkazis, H Misawa

    JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS   22 ( 7 )   1471 - 1478   2005年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    The criteria for lasing in a dielectric sphere surrounded by an active medium are given. They are presented in simple analytical form and confirmed by numeric calculations of the amplitudes of the morphology-dependent resonances in spontaneous emission spectra. The determined lasing threshold of this novel-type laser is compared with that of a conventional spherical laser with an optically active internal layer. The diverse advantages of a laser based on the gain of the evanescent part of a whispering-gallery mode are discussed. (c) 2005 Optical Society of America.

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  • Three-dimensional optical memory using a human fingernail 査読

    A Takita, H Yamamoto, Y Hayasaki, N Nishida, H Misawa

    OPTICS EXPRESS   13 ( 12 )   4560 - 4567   2005年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    We realized optical data storage in a human fingernail. A structural change is recorded by irradiating a focused femtosecond laser pulse and is read out with fluorescent observation by making use of an increased fluorescence intensity. The shape of the structural changes drastically depends on the irradiated pulse energy. The fluorescence spectrum of the structure coincided with the auto-fluorescence spectra of a fingernail and a heated fingernail. It is suggested that the increased fluorescence is most likely caused by a local denaturation of the keratin protein by the femtosecond laser pulse irradiation. We demonstrate that the increased fluorescence effect is useful for reading out three-dimensionally recorded data. (C) 2005 Optical Society of America.

    DOI: 10.1364/OPEX.13.004560

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  • Two-photon lithography of nanorods in SU-8 photoresist 査読

    S Juodkazis, Mizeikis, V, KK Seet, M Miwa, H Misawa

    NANOTECHNOLOGY   16 ( 6 )   846 - 849   2005年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Studies on two-photon lithography in negative SU-8 photoresist demonstrate the possibility of obtaining mechanically stable, stress-free, extended nanorods having lateral sizes of about 30 nm (corresponding to lambda/25 resolution). The high resolution achievable with the given combination of materials and fabrication techniques demonstrates its potential for the fabrication of large-scale nanostructures, such as photonic crystals with photonic stop gaps at visible wavelengths.

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  • Control of the molecular alignment inside liquid-crystal droplets by use of laser tweezers 査読

    N Murazawa, S Juodkazis, S Matsuo, H Misawa

    SMALL   1 ( 6 )   656 - 661   2005年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    Here, we demonstrate how the light-induced birefringence due to the dipole molecular realignment and anisotropic polarizability of a nematic liquid crystal inside a droplet changes the droplet's radial (and thus optically isotropic) structure into a birefringent one. This intensity-dependent change of birefringence can be understood in terms of the anisotropic polarizability and orientational optical nonlinear effect. Birefringence induced by laser tweezers changes the momentum of the passing light. In turn, for the circularly polarized tweezers, this change generates an angular momentum change large enough to spin micrometer-sized droplets. For the linearly polarized tweezers, the molecular ordering generates momentum, which laterally displaces the droplet. It is shown that the optical nonlinearity can be "large" enough to have mechanical (ponderomotive) implications, that is, it allows control of the movement and position of micro-objects with submicrometer resolution. The optically induced molecular alignment controlled by the polarization and power of the laser tweezers allows one to actuate, rotate, and translate objects which are up to 10(3)-10(4) times larger than the constituent molecules themselves.

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  • Three-dimensional spiral-architecture photonic crystals obtained by direct laser writing 査読

    KK Seet, Mizeikis, V, S Matsuo, S Juodkazis, H Misawa

    ADVANCED MATERIALS   17 ( 5 )   541 - +   2005年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

    A recently elaborated novel class of spiral-architecture photonic crystals, which has promising photonic bandgap properties, is realized by direct laser writing in SU-8 (see Figure). Such self-supporting structures show signatures of photonic stopgaps at infrared wavelengths, and can serve as accurate templates for infiltration of higher-refractive-index materials.

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  • Visualization of DNA hybridization on gold thin film by utilizing the resistance effect of DNA monolayer 査読

    T Masuda, A Yamaguchi, M Hayashida, F Asari-Oi, S Matsuo, H Misawa

    SENSORS AND ACTUATORS B-CHEMICAL   105 ( 2 )   556 - 561   2005年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE SA  

    We propose a novel detection method for a duplex formation of DNA on a solid substrate. In this method, DNA monolayers are prepared on a gold thin film, and then the substrate is treated by an etching process. Since the DNA monolayer can act as a resist layer, the thickness of the gold film in the regions covered by DNA monolayers is larger than that in the region without the monolayer. Furthermore, the difference in the resistance effect of ss- and ds-DNA monolayers induces the difference in the thickness of the gold thin film after the etching. The resistance effect of the ss-probe DNA monolayer increases as a result of the formation of a duplex with the target DNA. The sequence-specific hybridization adsorption of the target DNA can be detected visually by measuring the light transmittance of the gold film, or with the naked eye. Using this method, we succeeded in detecting two base pair mismatches in a 30-base pair nucleotide. (c) 2004 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.snb.2004.06.015

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  • Fabrication and electrochemical characterization of interdigitated nanoelectrode arrays 査読

    K Ueno, M Hayashida, JY Ye, H Misawa

    ELECTROCHEMISTRY COMMUNICATIONS   7 ( 2 )   161 - 165   2005年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE INC  

    Interdigitated nanoelectrode arrays with controlled electrode bandwidth and gap geometries ranging from 30 nm to 1 mum were fabricated on glass substrates by a planar process involving high resolution electron beam lithography and lift-off, and their characteristic electrochemical responses to an aqueous ferrocene derivative solution were examined using fundamental electrochemical techniques. Despite the comparatively large electrode area of electrode arrays containing 10 bands to a single band electrode, quasi-steady-state currents with high current density were obtained at a slow potential sweep rate in cyclic voltammograms of ferrocene derivative since the lateral dimension of the nanoelectrode arrays was considerably less than the scale of the diffusion layer of redox species. Additionally, it was demonstrated that the electrode thickness influenced limiting currents of voltammograms in the case of nanoelectrode arrays. In generation-collection mode experiments, furthermore, a collection efficiency as high as similar to99% was attained by 100 nm wide electrode arrays with a gap dimension of 30 nm. (C) 2004 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.elecom.2004.12.002

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  • Femtosecond laser microfabrication of periodic structures using a microlens array 査読

    S Matsuo, S Juodkazis, H Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   80 ( 4 )   683 - 685   2005年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    A microlens array (MLA) was applied for femtosecond laser microfabrication. Two-dimensional periodic patterns that corresponded to the arrangement of lenses in the MLA were recorded by ablation on a glass surface. The two-dimensional periodic patterns were recorded by a single exposure without scanning of the laser beam or the sample, and worked as a grating. Optical resizing of the patterns and high efficiency of fabrication are demonstrated and discussed.

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  • Ultrabright femtosecond source of biphotons based on a spatial mode inverter 査読

    Jarutis, V, S Juodkazis, Mizeikis, V, K Sasaki, H Misawa

    OPTICS LETTERS   30 ( 3 )   317 - 319   2005年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    A method of enhancing the efficiency of entangled biphoton sources based on a type II femtosecond spontaneous parametric downconversion (SPDC) process is proposed and implemented experimentally. Enhancement is obtained by mode inversion of one of the SPDC output beams, which allows the beams to overlap completely, thus maximizing the number of SPDC photon pairs with optimum spatiotemporal overlap. By use of this method, biphoton count rates as high as 16 kHz from a single 0.5-mm-long beta-barium borate crystal pumped by second-harmonic radiation from a Ti:sapphire laser were obtained. (C) 2005 Optical Society of America.

    DOI: 10.1364/OL.30.000317

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  • Two-photon laser lithography of photonic microstructures in photoresist SU-8 査読

    Mizeikis, V, KK Seet, S Juodkazis, Jarutis, V, H Misawa

    2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS   1037 - 1038   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IEEE  

    High quality three-dimensional micro-and nano-structures were fabricated in photoresist SU-8 by two-photon laser lithography. Extended periodic microstructures with so-called woodpile architecture are demonstrated to have good quality and exhibit fundamental and higher-order photonic stop-gaps in the infrared wavelength range of 2.0-8.0 mu m. These SU-8 structures can be used as photonic crystal templates suitable for infiltration by high refractive index materials. To illustrate the resolution limit of SU-8 material, we also demonstrate fabrication of SU-8 nanorods with ultrahigh resolution of about 30 nm.

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  • High sensitivity and large dynamic range surface plasmon resonance sensing for DNA hybridization using Au-nanoparticle-attached probe DNA 査読

    M Hayashida, A Yamaguchi, H Misawa

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   44 ( 50-52 )   L1544 - L1546   2005年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INST PURE APPLIED PHYSICS  

    In this study, we demonstrate the use of surface plasmon interaction between Au nanoparticles (GPs) and a Au thin film for enhancement of surface plasmon resonance (SPR) spectroscopy sensing for DNA hybridization. In situ DNA hybridization with a Au-nanoparticle-attached probe DNA (DNA-GP) monolayer is monitored by SPR spectroscopy, and the results reveal that the DNA-GP allows detection of unlabeled target DNA with the large dynamic range of 1 pM to 10 mu M.

    DOI: 10.1143/JJAP.44.L1544

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  • Photonic crystal templates obtained by two-photon laser lithography in photoresist SU-8 査読

    Mizeikis, V, KK Seet, S Juodkazis, Jarutis, V, H Misawa

    Ultrafast Lasers for Materials Science   850   149 - 154   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:MATERIALS RESEARCH SOCIETY  

    High quality templates of three-dimensional photonic crystals were fabricated in photoresist SU-8 using femtosecond laser lithography. The templates have woodpile and spiral architectures, which are widely expected to yield spectrally wide and robust photonic band gaps. Their opt characterization reveals fundamental and higher-order photonic stop-gaps in the infrared wavelength range of 2.0-8.0 mu m. These templates are mechanically stable, nearly free of shrinkage-related deformations, and can be used for subsequent infiltration by optically active or high refractive index materials.

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  • Control of period of titiania-organic hybrid pillar array derived from multi-beam laser interference technique 査読

    H Segawa, H Misawa

    2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS   978 - 979   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IEEE  

    Two-dimensional periodic pillar arrays have been produced from titania-organic hybrid film by multi-beam laser interference technique. The period of the arrays can be controlled by the laser energy and film thickness.

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  • Microrheology at the liquid-crystal water boundary 査読

    N Murazawa, S Juodkazis, Jarutis, V, Y Tanamura, H Misawa

    2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS   855 - 856   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IEEE  

    We demonstrate the viscosity measurement using laser-trapped liquid crystal droplet. The viscosity, determined experimentally depended on die diameter of the droplet and boundary conditions at the liquid crystal surface which was changed by adding surfactant.

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  • Three-dimensional spiral architecture photonic crystals obtained in a negative photoresist SU-8 by direct laser writing 査読

    KK Seet, Mizeikis, V, S Juodkazis, H Misawa

    2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS   1035 - 1036   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IEEE  

    Spiral architecture photonic crystals have been fabricated in a negative-tone photoresist SU-8 by direct laser writing. These photonic crystals are self-supporting and highly-periodic, and exhibit photonic attenuation in the range of 1.7 to 5.0 mu m..

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  • Two-photon excited fluorescence enhancement using nano-engineered gold particles 査読

    K Ueno, Mizeikis, V, S Juodkazis, K Sasaki, H Misawa

    2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS   857 - 858   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IEEE  

    Two-photon excited fluorescence of organic dye by embedding them with gold nanostructures fabricated on a glass substrate was enhanced on the basis of increasing electromagnetic field induced by nanogap configuration.

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  • Studies of femtosecond pulse filamentation in borosilicate glass 査読

    E Vanagas, E Gaizauskas, Mizeikis, V, Jarutis, V, S Juodkazis, H Misawa

    2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS   848 - 848   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IEEE  

    Light filament formation in borosilicate glass under femtosecond pulse irradiation was investigated. The main observations were successfully reproduced by numerical modeling.

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  • High efficiency femtosecond source of entangled photons 査読

    V. Jarutis, S. Juodkazis, V. Mizeikis, H. Misawa

    IQEC, International Quantum Electronics Conference Proceedings   2005   1008 - 1009   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    The method allowing enhance the eficiency of entangled photon sources based on Type II spontaneous parametric down conversion (SPDC) by means of mode inversion of one of the SPDC output beams is described. Overlap between the the entire signal in idler beams can be achieved using the mode inversion thus maximizing the SPDC photon pair yields. With this method, coincidence count rates as high as 60 kHz from a single 0.5 mm long bulk BBO crystal pumped by the second-harmonic radiation of a femtosecond Ti: Sapphire laser, were obtained.

    DOI: 10.1109/IQEC.2005.1561011

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  • Nanofabrication by direct laser writing and holography 査読

    Kock Khuen Seet, Vygandas Jarutis, Saulius Juodkazis, Hiroaki Misawa

    Proceedings of SPIE - The International Society for Optical Engineering   6050   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    The physical principles underlying a three-dimensional (3D) laser microstructuring technique are outlined, its applications for the fabrication of 3D (nano)micro-structured materials are presented. The direct laser writing and holographic recording in SU-8 photoresist are described. The limits of the lateral and axial light localization of a Gaussian pulse/beam at the focus are derived for the multi-photon absorption taking into account the threshold of photomodification. Prospective holographic patterns formed by interference of circularly and linearly polarized beams are discussed.

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  • Development of highly efficient two-photon absorption materials: Organic dye-inorganic nanolayered silicate hybrid systems 査読

    Y Tanamura, K Kamada, H Misawa

    2005 PACIFIC RIM CONFERENCE ON LASERS AND ELECTRO-OPTICS   859 - 860   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IEEE  

    We have developed highly efficient two-photon absorption (TPA) materials, which are consisted of organic TPA dye and inorganic nanolayered silicate (clay). Linear and nonlinear optical characterization for the TPA materials ware carried out.

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  • Processing structures on human fingernail surfaces using a focused near-infrared femtosecond laser pulse 査読

    Y Hayasaki, H Takagi, A Takita, H Yamamoto, N Nishida, H Misawa

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   43 ( 12 )   8089 - 8093   2004年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INST PURE APPLIED PHYSICS  

    We investigated the processing of a human fingernail surface using a tightly focused femtosecond laser pulse. The processed structure in the fingernail surface is strongly dependent on the focus position and irradiation energy of the single laser pulse. We observed a ring, a simple pit, a small pit with a surrounding uplift, an irregular jagged surface, and a swell containing a void, depending on the focus position. We also observed a sudden change in the size of the processed structure according to the irradiation pulse energy. From a linear theoretical estimation based on the diffraction of the laser beam, we found that the sudden change is primarily due to the diffraction pattern generated by the circular aperture of the objective lens. We also describe the processing features by comparing the structures processed in a fingernail with those processed in glass.

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  • Silicon-based Honeycomb Photonic Crystal Structures with Complete Photonic Band Gap at 1.5μmWavelength 査読

    S. Juodkazis, I. Maksimov, H. Misawa

    J. App. Phys.   96 ( 11 )   6934 - 6936   2004年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1063/1.1815045

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  • Thermal accumulation effect in three-dimensional recording by picosecond pulses 査読

    S Juodkazis, H Misawa, Maksimov, I

    APPLIED PHYSICS LETTERS   85 ( 22 )   5239 - 5241   2004年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    In-bulk recording without cracking in borosilicate glass by high repetition rate (80 MHz) 12 ps pulses at 355 nm wavelength is demonstrated and discussed. The theoretical model of a "hot-line" scan and thermal accumulation qualitatively well describes the experimental results. The analytical expression of a thermally induced stress was obtained. (C) 2004 American Institute of Physics.

    DOI: 10.1063/1.1829799

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  • Periodic structures of organic-titania hybrid materials recorded by multi-beam laser interference technique 査読

    H Segawa, J Tabuchi, K Yoshida, S Matsuo, H Misawa

    JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY   32 ( 1-3 )   287 - 291   2004年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Photosensitive organic-titania hybrid materials have been prepared from metal alkoxides and various organic ester compounds with C=C double bonds. The refractive index of the film increases with the decrease of the concentration of the organic ester compound, and the highest refractive index of 1.62 is obtained when 2-hydroxymethyl acrylate (HOA) is used as the organic ester and the molar ratio of HOA to Ti is 0.5. The material with the highest refractive index is exposed to femtosecond pulse using the multi-beam laser interference technique. After laser irradiation, the irradiated parts of the material are photopolymerized and periodic structures can be obtained by development of the unirradiated parts. In the case of laser irradiation of 120 mu J total energy for 5 min, the periodic structure obtained corresponds to 2D photonic crystal structure which is composed of two parts; the material with the highest refractive index and the air.

    DOI: 10.1007/s10971-004-5804-6

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  • Hole drilling in stainless steel and silicon by femtosecond pulses at low pressure 査読

    S Juodkazis, H Okuno, N Kujime, S Matsuo, H Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   79 ( 4-6 )   1555 - 1559   2004年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    We report on the ablation and hole drilling in stainless steel SUS304 and Si by femtosecond pulses (wavelength 800 nm; pulse duration &gt;80 fs) at the room and low (5 Torr) air pressure ambient. It was found that the quality of surface processing is improved at low pressure avoiding debris formation. The improvement is due to suppression of the conical emission, resulting from the air optical breakdown at a pre-surface area of sample. Debris-free processing of the movable Si-MEMS components is demonstrated. Techniques for the precise measurement of focal spot size and pulse duration are discussed.

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  • Formation of embedded patterns in glasses using femtosecond irradiation 査読

    S Juodkazis, K Yamasaki, Mizeikis, V, S Matsuo, H Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   79 ( 4-6 )   1549 - 1553   2004年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    Channel formation in glasses is demonstrated and discussed. Photosensitive glass (Foturan) was microstructured using femtosecond irradiation at 800 nm and 400 nm wavelengths, with subsequent thermal annealing, and HF etching of a lithium-silicate phase formed by exposure-annealing. It was found that there is a significant difference in the volume of lithium-silicate when the exposure was made with and without optical breakdown. Channels with a minimum cross section of approximately 10 mum were achieved.
    In silicate glasses, the optically induced dielectric breakdown was used for the recording of channel patterns. The highest wet etching rate in a HF based solution was observed when the irradiance corresponded to the 2.5-3.0 thresholds of dielectric breakdown and the adjacent pulses were overlapping by more than 50% of the diameter of the focussed beam. Under these conditions, the formation of a void inside the glass was confirmed by optical observation of single shot damage under a microscope. The mechanism of selective wet etching in silicate glasses is discussed in terms of the stress corrosion effect, which explains crack propagation in glasses via the reaction of stretched Si-O-Si bonds at the tip of a crack with water, resulting in SiOH formation. It is shown that intra-connection of voxels was the key factor to achieve etching of high aspect ratio patterns in silica glass.

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  • Three-dimensional woodpile photonic crystal templates for the infrared spectral range 査読

    Mizeikis, V, KK Seet, S Juodkazis, H Misawa

    OPTICS LETTERS   29 ( 17 )   2061 - 2063   2004年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OPTICAL SOC AMER  

    High-quality templates of three-dimensional woodpile photonic crystals are fabricated in photoresist SU-8 by use of femtosecond laser lithography. The samples have smooth surfaces, are mechanically stable, and are resistant to degradation under environmental and chemical influences. Fundamental and higher-order photonic stopgaps are identified in the wavelength range 2.0-8.0 mum. These templates can be used for subsequent infiltration by optically active or high-refractive-index materials. (C) 2004 Optical Society of America.

    DOI: 10.1364/OL.29.002061

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  • Controlled through-hole ablation of polymer microspheres 査読

    S Juodkazis, H Misawa

    JOURNAL OF MICROMECHANICS AND MICROENGINEERING   14 ( 8 )   1244 - 1248   2004年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We report on ablation of complex micro-patterns on/in polymethylmethacrylate (PMMA) microspheres of 2-7 mum diameter. By controlling the irradiation fluence, different ablation patterns can be reproduced: (i) the ablation of the opposite side to that irradiated, (ii) two-side ablation along the propagation of the beam and (iii) a through-hole ablation of the PMMA microsphere. Microspheres were laser trapped and held by tightly focused cw-illumination at 1064 nm while the ablation was carried out by a coaxial irradiation of a single laser pulse of 7 ns duration at 355 nm wavelength. Calculations of spatial intensity distribution of Mie light scattering by a laser-trapped microsphere corroborated the ablation patterns observed experimentally. Laser microfabrication of through-holes in microspheres is explained by the ablation-triggered shock waves. The ponderomotive action of the laser beam is discussed.

    DOI: 10.1088/0960-1317/14/8/018

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  • Fabrication of fine-pitch TiO2-organic hybrid dot arrays using multi-photon absorption of femtosecond pulses 査読

    H Segawa, S Matsuo, H Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   79 ( 3 )   407 - 409   2004年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

    TiO2-organic hybrid dot arrays were produced from TiO2-organic hybrid films by a multi-beam laser interference technique of ferntosecond laser pulses. The hybrid films were prepared from titanium alkoxide and beta-diketonate by the sol-gel method. Films were exposed to interference light from fermosecond pulses which have an intensity distribution over the pitch of the order of a micron. The chemical structures of the hybrid film were changed by multi-photon absorption from femtosecond pulses, and made chemical patterning possible after the development process. The precursor arrays of the TiO2-organic hybrid material were calcined at 450degreesC. TiO2-organic hybrid dot arrays with a refractive index of 2 were obtained.

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  • Optical characteristics of two-dimensional photonic crystals in anodic aluminum oxide films 査読

    Mizeikis, V, Mikulskas, I, R Tomasiunas, S Juodkazis, S Matsuo, H Misawa

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   43 ( 6A )   3643 - 3647   2004年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INST PURE APPLIED PHYSICS  

    The optical properties of two-dimensional photonic crystals (PhCs) in anodic aluminum oxide (AAO) films obtained using a simple and low-cost pre-patterning procedure are described. The prepatterning of the initial Al film surface was carried out by imprinting with an optical diffraction grating; the anodization of the prepatterned sample led to the formation of a good quality, large-area PhC with a triangular lattice of air holes (lattice period a = 0.48 mum, hole radius r = 0.2 mum) in an AAO film. The optical transmission spectra of the sample were measured at visible wavelengths in the range of 0.4-1.0 mum for various incidence angles and linear polarizations of the probing light. The detailed analysis of the transmission data indicates a photonic band gap in the 0.9-1.0 mum wavelength range for light waves linearly polarized in the direction perpendicular to the axes of PhC pores.

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  • Construction of DNA-Au nanoparticles multilayer and its application to detection of DNA hybridization 査読

    HC Liu, A Yamaguchi, M Hayashida, S Matsuo, H Misawa

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   43 ( 5A )   2767 - 2770   2004年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INST PURE APPLIED PHYSICS  

    We have developed a sensitive detection system for DNA hybridization containing DNA-Au nanoparticles (DNA-GPs) multilayer which leads to the enhancement of the detection sensitivity of surface plasmon resonance (SPR) signals. The SPR angular shift, which is the difference in the SPR angles before and after hybridization, becomes amplified with increasing number of layers of the DNA-GPs. A similar increase in SPR angular shift was obtained for the target DNA with low concentration. The reason for the enhancement is attributed to the interaction between Au nanoparticles and the Au film, as well as the increase in immobilized probe DNA content on the substrate.

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  • Three-dimensional microfabrication by femtosecond pulses in dielectrics 査読

    T Kondo, K Yamasaki, S Juodkazis, S Matsuo, Mizeikis, V, H Misawa

    THIN SOLID FILMS   453   550 - 556   2004年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE SA  

    We report femtosecond laser microfabrication in thin films of polymeric photoresists by (i) direct laser writing and (ii) holographic recording techniques. With (i) we have fabricated empty microchannels in polymethylmethacrylate; the channel width closely follows the intensity distribution in the focal spot of a high numerical aperture lens in accordance with scalar and vectorial Debye theory. With (ii) we have fabricated free-standing two-dimensional periodic structures in SU8 photoresist. The structures contain cylindrical pillars with noticeable ripple-like modulation of their diameter along their axes. This modulation results from the interference between the waves incident on the sample and back-reflected from the glass substrate or air, and is explained using an appropriate numerical modeling. (C) 2003 Elsevier B.V. All rights reserved.

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  • Intrinsic single- and multiple-pulse laser-induced damage in silicate glasses in the femtosecond-to-nanosecond region 査読

    O Efimov, S Juodkazis, H Misawa

    PHYSICAL REVIEW A   69 ( 4 )   042903   2004年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    We show that the threshold power density of the intrinsic laser-induced damage in borosilicate glass at similar to1 mum wavelength does not depend on pulse duration from 2x10(-13) to 3x10(-8) s and has the same value for both single- and multiple-pulse exposure of the sample. This indicates that the mechanism of the intrinsic damage in glasses involves a collective response of a certain volume in the dielectric as a whole, such as "dielectric-metal" phase transition, rather than a process of individual generation and accumulation of electrons, such as multiphoton, tunneling, or avalanche. Also, we demonstrate that under femtosecond exposure the threshold of the plasma formation in transparent glasses is considerably higher than the threshold of the residual change of medium parameters.

    DOI: 10.1103/PhysRevA.69.042903

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  • Glass cutting by femtosecond pulsed irradiation 査読

    E Vanagas, J Kawai, D Tuzhilin, Kudryashov, I, A Mizuyama, KG Nakamura, KI Kondo, SY Koshihara, M Takesada, K Matsuda, S Juodkazis, Jarutis, V, S Matsuo, H Misawa

    JOURNAL OF MICROLITHOGRAPHY MICROFABRICATION AND MICROSYSTEMS   3 ( 2 )   358 - 363   2004年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPIE-INT SOCIETY OPTICAL ENGINEERING  

    We report on quartz and glass cutting by a lateral scanning of femtosecond pulses (150 fs at 1 kHz repetition rate) of 800 nm wavelength at room and low pressure (5 Torr) air ambience. Pulses were focused by a low numerical aperture (NAless than or equal to0.1) objective lens. Optimization of fabrication conditions: pulse energy and scanning speed were carried out to achieve large-scale (millimeter-to-centimeter) cutting free of microcracks of submicron dimensions along the edges and walls of the cut. Cutting through out the samples of 0.1-0.5 mm thickness was successfully achieved without apparent heat affected zone. At low air pressure (5 Torr) ambience, redeposition of ablated material was considerably reduced. It is demonstrated that the damage on the rear surface was induced by the stress waves, which originated from the plasma ablation pressure pulse. The mechanism of femtosecond-laser cutting of transparent materials at high irradiance and the influence of stress waves generated by plasma plume are discussed. (C) 2004 Society of Photo-Optical Instrumentation Engineers.

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  • Optical bit recording in a human fingernail 査読

    A Takita, M Watanabe, H Yamamoto, S Matsuo, H Misawa, Y Hayasaki, N Nishida

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   43 ( 1 )   168 - 171   2004年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INST PURE APPLIED PHYSICS  

    Optical bit recording in a human fingernail is demonstrated by using a femtosecond laser processing technique. A bit is formed in a fingernail by irradiation of a focused femtosecond laser pulse. We have investigated the dependence of the irradiation pulse energy on the diameter and length of the formed bit. The bit diameter and length are theoretically explained based on a Gaussian beam irradiation model. Furthermore, the achievable recording density is estimated from the measured bit diameter and bit length. We have found that the pulse energy required to form a bit depends on the recording depth and the surface condition of the fingernail.

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  • Glass transition-assisted microstructuring in polystyrene 査読

    S Juodkazis, K Yamasaki, S Matsuo, H Misawa

    APPLIED PHYSICS LETTERS   84 ( 4 )   514 - 516   2004年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    We report on the use of a shape transition process to resize patterns prerecorded inside polystyrene film. The shape transition, which is shrinkage in two dimensions and expansion in the third (the volume is conserved), was brought about by annealing polystyrene above the glass transition temperature. This caused approximately twofold lateral shrinkage and fourfold axial stretching of the film, inside which micrometer-sized patterns had been recorded by femtosecond pulses. The transformation of these patterns corresponded to the macroscopic shape transformation of the film. The shape transition was also used to transform a diffraction grating. This allowed the transformation to be confirmed by the corresponding change in diffraction efficiency. The applicability of the shape transition process to nanofabrication is discussed. (C) 2004 American Institute of Physics.

    DOI: 10.1063/1.1641182

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  • Laser microfabrication of three-dimensional photonic crystal templates in polymers 査読

    Mizeikis, V, KK Seet, S Juodkazis, H Misawa

    FIFTH INTERNATIONAL SYMPOSIUM ON LASER PRECISION MICROFABRICATION   5662   95 - 100   2004年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    Three-dimensional woodpile photonic crystal structures were recorded in films of polymeric photoresists polymethylcrylate (PMMA) and SU-8 films by femtosecond laser microfabrication technique. The fabricated structures consist of periodic arrays of extended elliptical 'void-channels in PMMA, and of solid elliptical rods of cross-linked polymer in SU-8. Their lattice periods of several micrometers and typical sub-micrometric feature sizes allowed to confirm presence of pronounced photonic stop-bands at infrared wavelengths around 2.0-8.0 mum.

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  • A Transparent Microchannel Chip for Quantitative PCR 査読

    K. Sun, Z. Li, S. Matsuo, H. Misawa

    Transactions of the Materials Research Society of Japan   29 ( 1 )   339 - 342   2004年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Surface Plasmon Resonance Imaging Detection of DNA Hybridization Using Colloidal Au Attached Probe DNA 査読

    M. Hayashida, H. Liu, A. Yamaguchi, S. Matsuo, H. Misawa

    Transactions of the Materials Research Society of Japan   29 ( 1 )   335 - 337   2004年

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  • Laser Fabrication of Two-Dimensional Periodic Arrays of a TiO2-Organic Hybrid Material 査読

    H. Segawa, S. Matsuo, H.Misawa

    Proc. XX ICG   0-11-030   2004年

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  • T. Kondo, K.Yamasaki, S. Juodkazis, S. Matsuo, V.Mizeikis and H. Misawa 査読

    Three-Dimensional Microfabrication by Femtosecon, Pulses in Dielectrics

    Thin Solid Films   453   550 - 556   2004年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Three-dimensional recording and structuring of chalcogenide glasses by femtosecond pulses 査読

    S Juodkazis, T Kondo, A Rode, S Matsuo, H Misawa

    FIFTH INTERNATIONAL SYMPOSIUM ON LASER PRECISION MICROFABRICATION   5662   179 - 184   2004年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    We report on three-dimensional (3D) holographic recording in AS(2)S(3) glass using 800 nm wavelength, 150 fs duration pulses. Diffractive beam splitter was used to generate 2 - 5 beams which were then focused for recording by objective lens of numerical aperture NA = 0.75. The recorded 3D hologram was read out by diffraction of 632 nm HeNe laser beam confirming the expected pattern of holograms. The mechanism of photo-darkening and optical damaging of AS(2)S(3) glass and dielectrics in general is discussed. Two-photon absorption cross-section, sigma(2) = 74.6 x 10(-50) cm(4)/(S), was determined by transmission for pulses of 150 fs and 800 nm wavelength. Also, it is demonstrated that the optical damage threshold scales as the bandgap energy for the fluorides. Nano-/ rnicro-structuring of AS(2)S(3) glass by ablation in air will be also demonstrated. High fluence ( &gt; 5 J/cm(2)) irradiation of the 800 ran wavelength, 150 fs duration pulses was used to ablate AS(2)S(3) glass. Self-organized growth of the fibers, rods, and microsphere-type structures was observed. Composition of the nano-/micro-structured material was close to that of the source AS(2)S(3) glass (with up to 20% surplus of sulphur in nano-rods). Straight rods as thin as 20 nm in diameter and over 1 pm-long were obtained. Application potential of nano-/microstructured AS(2)S(3) glass is discussed.

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  • Two-directional TiNi shape memory alloy film 査読

    H Takagi, K Okano, S Juodkazis, S Matsuo, H Misawa

    ADVANCED ENGINEERING MATERIALS   5 ( 10 )   732 - 735   2003年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:WILEY-V C H VERLAG GMBH  

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  • Recording and reading of three-dimensional optical memory in glasses 査読

    S Juodkazis, AV Rode, EG Gamaly, S Matsuo, H Misawa

    APPLIED PHYSICS B-LASERS AND OPTICS   77 ( 2-3 )   361 - 368   2003年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER-VERLAG  

    We report on three-dimensional (3D) optical memory recording and reading in glass by femtosecond pulses. Optically induced dielectric breakdown of glass is a mechanism of recording. The formulae of dielectric breakdown presented are applicable, in principle, for any crystalline or amorphous dielectric material. Scaling dependences of the probabilities of multi-photon and impact ionization are given. The measured threshold of an in-bulk dielectric breakdown of silica was reproduced numerically by implementing the ionization potential of Si (8.15 eV) for calculations. Exact measures of focal spot size and pulse duration at the focus allowed us to evaluate the intensity of a pulse during recording of 3D optical memory bits with high accuracy. The readout of the 3D optical memory was carried out by the white-light continuum generated from the previously damaged sites (recorded memory bits). The mechanism of the readout was a four-photon parametric interaction.

    DOI: 10.1007/s00340-003-1224-5

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  • Silicon surface processing techniques for micro-systems fabrication 査読

    Mizeikis, V, S Juodkazis, JY Ye, A Rode, S Matsuo, H Misawa

    THIN SOLID FILMS   438   445 - 451   2003年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE SA  

    Micromachining of silicon surface and near-surface regions by electron-beam lithography (EBL) and reactive ion dry-etching (RIE), as well as by laser microfabrication techniques is described. Combination of EBL and RIE techniques is used to fabricate quasi two-dimensional (213) photonic crystal (PhC) structures with aspect ratios at approximately 15. Structural and optical properties of PhC samples with 2D honeycomb lattice are reported, and a complete photonic band gap at wavelengths approximately 2.16 mum is identified from the optical transmission data. Next, laser microfabrication of silicon by femtosecond laser pulses is reported. Processing of silicon under low air pressure conditions (similar or equal to5 Tort) is demonstrated to be essentially debris-free process, highly suitable for cutting and scribing of wafers as well for hole drilling. Removal of thin films from the silicon surface by a single-shot laser ablation using mask projection is also demonstrated. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0040-6090(03)00803-4

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  • Efficient microvalve driven by a Si-Ni bimorph 査読

    S Tomonari, H Yoshida, M Kamakura, K Yoshida, K Kawahito, M Saitoh, H Kawada, S Juodkazis, H Misawa

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   42 ( 7A )   4593 - 4597   2003年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INST PURE APPLIED PHYSICS  

    We report on a new type of high-throughput thermally driven microvalve fabricated by using micro-electromechanical system (MEMS) technology. A miniaturized Si-Ni bintorph actuator was incorporated into the valve structure. This allowed the realization of both larger force generation and a longer stroke (the actuation length) combined with shortened response time. Also, a low-voltage actuation (&lt; 3 V) and low-energy consumption (&lt;0.2 W) were achieved. The actual size of the fabricated valve is 7.3 x 5.8 x 1.2 mm(3). The flow rate of 0 to 500 cm(3)/min at an air pressure of 47 kPa with a low leakage rate of 0.03 cm(3)/min and good linearity of air pressure control were achieved. The principles of design and experimental results on flow rate control are presented and discussed.

    DOI: 10.1143/JJAP.42.4593

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  • Miniaturization of a thermally driven Ni vertical bar Si bimorph 査読

    S Tomonari, H Yoshida, M Kamakura, K Yoshida, K Kawahito, M Saitoh, H Kawada, S Juodkazis, H Misawa

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   42 ( 7A )   4464 - 4468   2003年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INST PURE APPLIED PHYSICS  

    We report on the development of a thermally isolated bimorph structure based on a Ni/Si pair. A 1-mm-long beam of the bimorph was thermally isolated by a polyimide comb from the rest of the Si structure. The Si and Ni layers of the bimorph were 20 put thick. This geometry enabled us to generate the bending displacement (the stroke) of the free end of the bimorph up to 100 mum at about 100degreesC With a generated force of about 15 mN. Electrical power consumption for the 100degreesC working point was lower than 0.2W and the response time was 0.5s. This design entitles further miniaturization of micro-electromechanical systems (MEMSs) such as commercial microvalve structures and sensors. The principles of design and experimental results of temperature distribution for the bimorph are presented and discussed.

    DOI: 10.1143/JJAP.42.4464

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  • On-demand micro droplets manipulation system using laser trapping 査読

    Y Tanaka, A Murakami, Y Kinouchi, H Misawa

    ELECTRONICS LETTERS   39 ( 13 )   1023 - 1024   2003年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEE-INST ELEC ENG  

    A three-dimensional (3-D) manipulation system for micro droplets generated on-demand is presented. This newly developed system using focused trapping laser beams is able to manipulate pico- to femtolitre (that is, micron-sized) droplets independently and directly. The capability of the system is demonstrated by aligning oil droplets in water. Dependence of the volume of generated droplets on some control parameters is also described.

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  • High-efficiency optical transfer of torque to a nematic liquid crystal droplet 査読

    S Juodkazis, S Matsuo, N Murazawa, Hasegawa, I, H Misawa

    APPLIED PHYSICS LETTERS   82 ( 26 )   4657 - 4659   2003年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    We report on the determination of the difference in the refractive index between the ordinary and extraordinary rays in droplets of nematic liquid crystal E-44 at the wavelength of laser trapping, 1064 nm. This difference was calculated by measuring the ellipticity of laser tweezers for the moment at which rotation of the trapped droplet starts. The precision of this determination of the refractive index difference is approximately 5x10(-3). Hydrophobic nematic liquid crystal E-44 formed 0.5-5-mum droplets when cast into D2O. The efficiency of the transfer of light torque to the liquid crystal droplets was determined to be 70% for the no-slip-boundary condition. (C) 2003 American Institute of Physics.

    DOI: 10.1063/1.1588366

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  • Formation of free-standing micropyramidal colloidal crystals grown on silicon substrate 査読

    S Matsuo, T Fujine, K Fukuda, S Juodkazis, H Misawa

    APPLIED PHYSICS LETTERS   82 ( 24 )   4283 - 4285   2003年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    The self-organization of microspheres is one of the simplest methods for fabricating three-dimensional (3D) photonic crystals (PhCs), but the 3D structure of such organized microspheres, colloidal crystals, is difficult to control. In this letter, we report a method for forming face-centered-cubic colloidal crystals into a pyramidal shape on an anisotropically etched silicon (100) and (110) substrate. The colloidal crystals were lifted from the substrate for observation after thermal bonding. Free-standing colloidal crystals with a well-defined "micropyramid" shape were obtained. This type of PhC formation is suitable for batch production as well as for handling a single pyramid. (C) 2003 American Institute of Physics.

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  • Surface nanostructuring of borosilicate glass by femtosecond nJ energy pulses 査読

    E Vanagas, Kudryashov, I, D Tuzhilin, S Juodkazis, S Matsuo, H Misawa

    APPLIED PHYSICS LETTERS   82 ( 17 )   2901 - 2903   2003年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    We report on a feature, that of hillock-shaped damage, formed on a glass surface by femtosecond pulses of t(p)=180 fs [full width at half maximum (FWHM) value] duration produced by a recording beam focus with energy of 5 nJ/pulse at 800 nm wavelength (the corresponding irradiance of about 7.6 TW/cm(2) was evaluated for a 0.68 mum FWHM spot size). Single hillocks of 40-50 nm height were recorded reproducibly in single-pulse irradiation. Surface nanopatterning over a large, curved area (over 200 mum(2)) can be achieved by implementing a confocal surface curvature tracking method that utilizes the reflection of a supplementary cw-laser beam. The ablation pattern achieved by this method is consistent with that of a Coulomb explosion. (C) 2003 American Institute of Physics.

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  • Multiphoton fabrication of periodic structures by multibeam interference of femtosecond pulses 査読

    T Kondo, S Matsuo, S Juodkazis, Mizeikis, V, H Misawa

    APPLIED PHYSICS LETTERS   82 ( 17 )   2758 - 2760   2003年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    Femtosecond laser pulses are useful for laser microfabrication through multiphoton absorption. However, it is difficult to create interference of femtosecond pulses for the fabrication of periodic structures. In this letter, we report the fabrication of two-dimensional periodic structures by means of multibeam interference of femtosecond pulses. Scanning electron microscopy revealed a rod structure arranged into a square lattice. The possibility of controlling the period of the lattice, rod thickness, and rod shape were demonstrated. (C) 2003 American Institute of Physics.

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  • Dielectric breakdown of rubber materials by femtosecond irradiation 査読

    K Yamasaki, S Juodkazis, T Lippert, M Watanabe, S Matsuo, H Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   76 ( 3 )   325 - 329   2003年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER-VERLAG  

    We report the reversible micro-structuring of a synthetic rubber polymer (cis 1,4-polybutadiene (PB)) by femtosecond laser illumination. Visco-elastic relaxation of the optically damaged region was observed. The recovery time, typically 10(2)-10(4) ms, can be varied by changing the irradiation pulse energy. Multi-shot-induced damage recovers on the much longer scale of 10(1)-10(2) s. It was found that the doping of PB by 4 wt. % of pentazadiene ([4-NO2]-phenyl-N=N-N(C3H7)-N=N-phenyl-[4-NO2]) reduces the threshold of light-induced photo-modification by 20%. This is explained by photo-induced (homolytic) cleavage of the pentazadiene bonds and formation of gaseous N-2, which facilitates material failure at the irradiated spot.
    The recovery of optical transmission can be applied to optical memory, optical and micro-mechanical applications. The underlying mechanism of the phenomenon is discussed in terms of anelastic alpha- and beta-relaxation (polymer backbone and chains/coils relaxation, respectively).

    DOI: 10.1007/s00339-002-1816-7

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  • Effect of refractive index-mismatch on laser microfabrication in silica glass 査読

    A Marcinkevicius, Mizeikis, V, S Juodkazis, S Matsuo, H Misawa

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   76 ( 2 )   257 - 260   2003年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER-VERLAG  

    We studied the peculiarities of femtosecond laser microfabrication in silica glass with a refractive index that did not exactly match the value for which the focusing optics is designed. Spherical aberrations resulting from a small refractive index mismatch were found to increase the size and distort the shape of photodamaged regions, thus reducing the spatial resolution of the microfabrication. However, these undesirable effects can be minimized, providing that the focusing depth inside the glass is not too large, and the laser intensity is kept close to the light-induced damage threshold.

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  • Fabrication of photonic crystal structures by femtosecond laser-induced photopolymerization of organic-inorganic film 査読

    H Segawa, K Yoshida, T Kondo, S Matsuo, H Misawa

    JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY   26 ( 1-3 )   1023 - 1027   2003年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:KLUWER ACADEMIC PUBL  

    We report on a fabrication of photonic crystal structures in organic-inorganic hybrid films by a laser interference technique. Films containing the methacrylic group, which is photopolymerable by an adequate laser light, are prepared using a sol-gel technique from a mixture of organosilicate alkoxide and zirconium alkoxide modified by methacrylic acid. For the photopolymerization, the coated films on glass substrate are exposed to the interference light which is arranged with a square lattice in about 1 mum spacing. From microscopic images of microstructures produced by the photopolymerization, the influence of changes in conditions such as pre-bake temperature, photoinitiator and irradiation energy (laser power and duration time) on periodic structure is investigated. Adjusting the conditions, 2D and 3D photonic crystal structures with the micrometer-order period are formed in organo-silicate-zirconate hybrid materials.

    DOI: 10.1023/A:1020729917721

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  • Laser-Asisted Microfabrication by Using Gauss-Bessel Pulses: The Evidence of Self-action 査読

    E. Vanagas, V. Jarutis, S. Juodkazis, V. Mizeikis, I. Kudryashov, S. Matsuo, H. Misawa, R. Tomasiunas

    Lithuanian Journal of Physics   43 ( 4 )   243 - 250   2003年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Collective excitation of transparent dielectrics under femtosecond pulses 査読

    O. Efimov, S. Juodkazis, S. Matsuo, H. Misawa

    2003 European Quantum Electronics Conference, EQEC 2003   82   2003年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:Institute of Electrical and Electronics Engineers Inc.  

    The goal of this work is to measure the intrinsic laser-induced damage (LID) of a borosilicate glass for femtosecond pulses and to compare it with data obtained for the nanopicosecond region under conditions when self-focusing is avoided. This study demonstrates that the intrinsic LID irradiance of industrial borosilicate glass does not depend on pulse duration for 2 × 10-13 - 3 × 10-8s pulses. This finding is in favor of the LID mechanism, which is based on the phase transition scenario, rather than the currently accepted view based on a multi-photon ionization with ensuing avalanche development.

    DOI: 10.1109/EQEC.2003.1313939

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  • Irreversible modification of transparent dielectrics without plasma formation under femtosecond pulses 査読

    O. Efimov, S. Juodkazis, S. Matsuo, H. Misawa

    Conference on Lasers and Electro-Optics Europe - Technical Digest   559   2003年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    The goal of the present research was a study of the accumulation effect in transparent glasses and crystals under multishot irradiation by femtosecond pulses. The laser damage durability of optical components is important in the case of femtosecond pulses because of their wide application with high repetition rates for material treatments. It is concluded that, we have found existence of «cold» damage before plasma formation is reached. © 2003 IEEE.

    DOI: 10.1109/CLEOE.2003.1313621

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  • Single and multiple pulse laser-induced breakdown in transparent dielectrics in the femto-nanosecond region 査読

    OM Efimova, S Juodkazis, H Misawa

    LASER-INDUCED DAMAGE IN OPTICAL MATERIALS: 2003   5273   61 - 73   2003年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    This review is devoted to a long-term investigation into the nature of the laser-induced damage of silicate glasses. As an important result, we show that the threshold power density of the intrinsic damage of the boro-silicate glass at similar to1 mum wavelength does not depend on pulse duration from 2x10(-13) to 3x10(-8) s as long as self-focusing is avoided. This result cannot be explained by existing theories and indicates that the damage mechanism involves a collective response of a certain volume in the dielectric as a whole, rather than the accumulation of electrons via individual generation processes like multiphoton, tunneling, or avalanche. Special attention in the research was paid to investigation into the processes of multiple pulse damage and subthreshold modification of boro- and lead-silicate glasses.

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  • Photosensitive organic-inorganic hybrid films for photonic crystal using sol-gel process 査読

    H Segawa, J Tabuchi, K Yoshida, T Kondo, S Matsuo, H Misawa

    EMERGING FIELDS IN SOL-GEL SCIENCE AND TECHNOLOGY   331 - 340   2003年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:KLUWER ACADEMIC PUBLISHERS  

    Photonic crystals have a periodic structure composed of two dielectric materials with different refractive indices. Recently, we produced the photonic crystal structures composed of an organic-inorganic material and air. However, the refractive index of the material was not enough high to realize the photonic band gaps. In this study, we investigate photopolymerizable organic-inorganic materials with higher refractive index for the photonic crystals. The two-dimensional photonic crystal is produced from the material using the laser interference technique.

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  • Application of Consolidation Method to the Recycling of Grinding Swarf of Bearing Steel 査読

    K. Yamamoto, H. Takagi, H. Misawa, M. Morimoto

    The Japan Society of Mechanical Engineers   69 ( 679 )   678 - 681   2003年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:一般社団法人日本機械学会  

    This paper deals with the recycling of bearing steel grinding swarf by high-density consolidation. The grinding swarf was compacted at the pressing pressure from 98 to 588 MPa. The maximum density of 5.41 g/cm3 was obtained at the pressing pressure of 588 MPa. Metal recovery rate that is one of the most important factors in metal recycling depended on the density of the grinding swarf briquet. The metal recovery rate of about 90% was obtained at the density of 4.8 g/cm3. Chemical compositions of original bearing steel (SUJ 2) and recycled metals obtained from melting of grinding swarf briquets in air and Ar were evaluated.

    DOI: 10.1299/kikaia.69.678

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  • Three-dimensional recording by femtosecond pulses in dielectrics 査読

    S Juodkazis, T Kondo, Mizeikis, V, S Matsuo, H Murata, H Misawa

    PHOTON PROCESSING IN MICROELECTRONICS AND PHOTONICS II   4977   94 - 107   2003年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    Fabrication and characteristics of two-dimensional (2D) and three-dimensional (3D) periodic structures, recorded in the bulk of SU8 photoresist film by multiple-beam interference is described. Multiple beams (up to nine.) were generated by a diffractive beam splitter. Recording was performed by ultrashort laser pulses with temporal width of 140 fs (FVWM) and central wavelength of 800 nm, derived from a Ti:sapphire laser. Intensity-dependent photomodification of the photoresist was due to single-photon as well as multi-photon (two and three) absorption. After the development, the exposed resist films contained free-standing 2D and 3D periodic dielectric structures with unexposed exposed regions removed by the development. Detailed examination of the samples has revealed close resemblance between their structure and the light intensity distributions in the multiple-beam interference. fields, expected from the numerical calculations. Quality of the samples recorded by a single-photon absorption was lower than that of that of other samples, in particular due to poor development quality. The microfabrication method used in this work appears to be a suitable for obtaining photonic crystal templates.

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  • Recording by focusing femtosecond laser pulse and fluorescence readout of three-dimensional optical memory in human nail 査読

    A. Takita, H. Yamamoto, Y. Hayasaki, H. Misawa, N. Nishida

    Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest   2   691   2003年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:Institute of Electrical and Electronics Engineers Inc.  

    Three-dimensional optical bit recording with a femtosecond laser pulse and bit observation with atomic force microscope and fluorescence observation in human finger nail are performed. Shapes of a bit and changes of the fluorescence of nail is investigated. The bit is formed by micro-explosion and the fluorescence intensity is increased with a irradiation of a femtosecond laser pulse.

    DOI: 10.1109/CLEOPR.2003.1277232

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  • Electromagnetic Wave Absorption Characteristics of Light Board Made with Recycled Polyester Fiber, Magnetite and Carbon 査読

    H. Kawai, H. Takagi, H. Misawa, Y. Kondo

    Adv. in Tech. of Mat. and Mat. Proc. J.   5 ( 1 )   7 - 12   2003年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Fabrication and optical characteristics of silicon-based two-dimensional photonic crystals with honeycomb lattice 査読

    JY Ye, Mizeikis, V, Y Xu, S Matsuo, H Misawa

    OPTICS COMMUNICATIONS   211 ( 1-6 )   205 - 213   2002年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We report on the fabrication and properties of quasi-two-dimensional photonic crystals (Phcs) with honeycomb lattices of dielectric rods in air. Photonic crystals, fabricated in silicon by electron beam lithography and dry-etching techniques, had the high aspect ratio of 12, corresponding to a rod height of about 7 mum. The optical transmission spectra of the samples measured in the 1.8-8 mum wavelength range, revealed pronounced features of photonic band dispersion, and a signature of a complete photonic band gap (PBG) centered at 2.3 mum wavelength. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0030-4018(02)01922-3

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  • Application of femtosecond laser pulses for microfabrication of transparent media 査読

    S Juodkazis, S Matsuo, H Misawa, Mizeikis, V, A Marcinkevicius, HB Sun, Y Tokuda, M Takahashi, T Yoko, J Nishii

    APPLIED SURFACE SCIENCE   197   705 - 709   2002年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Femtosecond laser microfabrication of 3D optical memories and photonic crystal (PhC) structures in solid glasses and liquid resins are demonstrated. The optical memories can be read out from both transmission and emission images. The PhC structures reveal clear signatures of photonic bandgap (PBG) and microcavity formation. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0169-4332(02)00397-5

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  • Rapid fabrication of electrochemical enzyme sensor chip using polydimethylsiloxane microfluidic channel 査読

    A Yamaguchi, P Jin, H Tsuchiyama, T Masuda, K Sun, S Matsuo, H Misawa

    ANALYTICA CHIMICA ACTA   468 ( 1 )   143 - 152   2002年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Applicability of polydimethylsiloxane (PDMS) for easy and rapid fabrication of enzyme sensor chips, based on electrochemical detection, is examined. The sensor chip consists of PDMS substrate with a microfluidic channel fabricated in it, and a glass substrate with enzyme-modified microelectrodes. The two substrates are clamped together between plastic plates. The sensor chip has shown no leakage around the microelectrodes under continuous solution flow (34 mul/min). Amperometric response of the sensor chips developed in this work suggest that various types of enzyme sensors can be designed by using PDMS microfluidic channels. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0003-2670(02)00634-7

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  • Flexural rigidity of a single microtubule 査読

    T Takasone, S Juodkazis, Y Kawagishi, A Yamaguchi, S Matsuo, H Sakakibara, H Nakayama, H Misawa

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   41 ( 5A )   3015 - 3019   2002年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:INST PURE APPLIED PHYSICS  

    Microtubules, which are flexible biopolymers, can be used for nanotechnology applications (e.g., nano-actuator) as they have a rigidity similar to that of plexyglass and other plastic materials. The flexural rigidity, or bending stiffness, of microtubules was measured using a laser trapping technique and dark-field microscopy. One end of a microtubule rod was chemically bound to a glass microsphere, while the other end was bound to a silica glass substrate. Then, the microsphere was laser-trapped and manipulated to exert three different deformation modes on the microtubule. The values of flexural rigidity for these deformations were between 10(-25) and 10(-23) Nm(2) as measured for the 5-25 mum length microtubules. The origin of the length dependence of the flexural rigidity of microtubules is discussed.

    DOI: 10.1143/JJAP.41.3015

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  • A heater-integrated transparent microchannel chip for continuous-flow PCR 査読

    K Sun, A Yamaguchi, Y Ishida, S Matsuo, H Misawa

    SENSORS AND ACTUATORS B-CHEMICAL   84 ( 2-3 )   283 - 289   2002年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE SA  

    A microchannel chip for continuous-flow polymerase chain reaction (PCR) was developed using transparent materials. The microchannel was fabricated on a quartz glass substrate using standard photolithography and wet-etching techniques and was sealed by another quartz glass substrate. Two indium-tin-oxide (ITO) films were deposited on the etched substrate as a thermal source. To confirm the temperature distribution in the microchannel, we measured the fluorescence spectra of an aqueous solution of 1-pyrenesulfonic acid sodium salt (PS-Na), which is a temperature-indicator dye, in the microchannel under a continuous solution flow. The results confirm that the temperature distribution on the microchannel's ITO films was almost uniform (within +/-2 degreesC) under two flow rates (56 and 152 nl/min). The slightness of this deviation indicates that the ITO films integrated into the microchannel chip can be very useful as a thermal source for PCR. An amplification of a 450 bp segment of Escherichia coli HB101 was successfully per-formed by two-stage (94 and 67 degreesC) thermal cycling on the chip device. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0925-4005(02)00016-3

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  • Direct measurement of laser power through a high numerical aperture oil immersion objective lens using a solid immersion lens 査読

    Shigeki Matsuo, Hiroaki Misawa

    Review of Scientific Instruments   73 ( 5 )   2011 - 2015   2002年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1063/1.1470231

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  • Morphology-dependent resonant laser emission of dye-doped ellipsoidal microcavity 査読

    S Juodkazis, K Fujiwara, T Takahashi, S Matsuo, H Misawa

    JOURNAL OF APPLIED PHYSICS   91 ( 3 )   916 - 921   2002年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    We report a morphology-dependent resonance (MDR) laser emission of rhodamine-doped ellipsoidal microcavity of the poly(methylmethacrylate) particles. Elliptical particles showed different lasing properties: the lasing threshold, intramode spectral separation, mode intensity, and spectral position, when an excitation is pointed to the different locations on the particle. This differs from the well-understood MDR lasing in spherical microparticles. (C) 2002 American Institute of Physics.

    DOI: 10.1063/1.1426240

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  • Enhancement of surface plasmon resonance sensing for DNA hybridization using colloidal an attached probe DNA 査読

    A Yamaguchi, S Juodkazis, S Matsuo, H Misawa

    CHEMISTRY LETTERS   ( 2 )   190 - 191   2002年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    In this study, we demonstrate that the Au particle modified probe DNA monolayer can enhance the surface plasmon resonance (SPR) signal for measuring hybridization of unlabeled DNA molecules. The Au particles adsorbed on single stranded (ss)- and double stranded (ds)-DNA monolayers have different optical interaction with surface of Au thin film, and this difference induces the enhancement of the SPR signal.

    DOI: 10.1246/cl.2002.190

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  • Surface plasmon resonance imaging of Au nano-partifcle modified DNA monolayers 査読

    A Yamaguchi, M Hayashida, S Juodkazis, Y Hara, S Matsuo, H Misawa

    BIOMEDICAL NANOTECHNOLOGY ARCHITECTURES AND APPLICATIONS   4626   247 - 251   2002年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    A probe DNA monolayer modified with Au nano-particles was prepared on an Au thin film and used for DNA hybridization detection by surface plasmon resonance (SPR) spectroscopy. This Au particle modified probe DNA monolayer resulted in about a 3.5 times larger SPR angle shift according to the hybridization reaction, compared to that found in a non-modified probe DNA monolayer. By comparison of the SPR image of the particle modified and non-modified probe DNA monolayer, this modification method was shown to be useful in improving the SPR signal for the detection of the unlabelled DNA molecules.

    DOI: 10.1117/12.491216

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  • Microfabrication of Three-Dimentional Structures in Polymer and Glass by Femtosecond Pulses 査読

    S. Juodkazis, T. Kondo, V. Mizeikis, S. Matsuo, H. Misawa, E. Vanagas, I. Kudryashov

    Lithuania Bilateral Conference on Optoelectoronics and Magnetic Materials Proc.   2002年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

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  • Advantages and Short comings of Femtosecond Laser Microfabrication 査読

    H. Misawa, S. Juodkazis, S. Matsuo, V. Mizeikis, A. Marcinkevicius

    Proc. of JUSFA 2002   2002年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

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  • Microfabrication by a high fluence femtosecond exposure: Mechanism and applications 査読

    M Watanabe, S Juodkazis, J Nishii, S Matsuo, H Misawa

    PHOTON PROCESSING IN MICROELECTRONICS AND PHOTONICS   4637   159 - 168   2002年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    We report the observation of 3/2-frequency generation during an Optically-induced failure of silica under femtosecond laser pulse irradiation. The origin of 3/2-frequency generation is due to a two-plasmon decay instability, which occurs at the quarter critical density of free charge carriers. We observed this emission during the optical damaging of glasses by tightly focused (numerical aperture of the objective lens was 0.5-1.35) femtosecond laser pulses. The pulse duration at the irradiation spot was about 0.35 ps, the energy 25-250 nJ, and the damage was recorded in a single shot event inside the glass. The emission at about 530 nm was only present in the spectra measured during an optical damage by 795 nm irradiation with the pulse energy 9 times and more higher than the threshold.
    We observed a new phenomenon applicable for microstructuring of glass. The high energy fs pulses (50-200 muJ) were focused by a plano-convex lens (focal length 2-10 cm) on the exit surface of a glass plate. The surface was ablated and the ablation was transferred into a volume of glass by translation of a "plasma spark". The length of such a channels can by up to few-cm and with a diameter of tens-of-micrometers. The mechanism and application of high-fluence fs fabrication in dielectrics is discussed.

    DOI: 10.1117/12.470618

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  • Fabrication of three-dimensional photonic crystals by femtosecond laser interference 査読

    S Matsuo, T Kondo, S Juodkazis, Mizeikis, V, H Misawa

    PHOTONIC BANDGAP MATERIALS AND DEVICES   4655   327 - 334   2002年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    We describe a novel microfabrication method based on interference of several coherent laser pulses in photosensitive media. The method allows to transform the periodic multidimensional interference patterns into periodic modulation of dielectric properties of the material, and is therefore potentially suitable for the photonic crystal fabrication in materials like photoresists, photosensitive glasses, and others. We have fabricated one, two, and three-dimensional photonic crystals with different lattices and sub-micrometer periods. The fabricated structures have high structural quality, as evidenced by confocal and scanning electron microscopies. Furthermore, using numerical simulations we explore the possibilities to obtain body-centered-cubic and diamond photonic crystal lattices by varying optical phases of the interfering beams. Numerical simulations are also used to reveal photonic bandgap properties of some 2D phhotonic crystals, fabricated using this technique.

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  • Microstructuring of silica and polymethylmethacrylate glasses by femtosecond irradiation for MEMS applications 査読

    S Juodkazis, K Yamasaki, A Marcinkevicius, Mizeikis, V, S Matsuo, H Misawa, T Lippert