Organization
Faculty of Environmental, Life, Natural Science and Technology Professor
Position
Professor
External link
Yasushi Takahashi
Research History
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Okayama University 環境生命自然科学研究科 Professor
2025.4
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Osaka Metropolitan University Graduate School of Engineering Associate Professor
2022.4 - 2025.3
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Osaka Prefecture University Graduate School of Engineering Associate Professor
2014.10 - 2022.3
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Osaka Prefecture University 21世紀科学研究機構 Associate Professor
2014.4 - 2014.9
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JST さきがけ研究員
2009.10 - 2013.3
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Osaka Prefecture University 21世紀科学研究機構
2009.4 - 2014.3
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京都大学大学院 ポスドク研究員
2006.4 - 2009.3
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東京大学大学院
2001.4 - 2006.3
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慶応義塾大学
1997.4 - 2001.3
Papers
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Yu Shimomura, Takashi Asano, Ayumi Ishihara, Susumu Noda, Yasushi Takahashi
Optics Express 33 ( 8 ) 18515 - 18515 2025.4
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Yuki Saito, Takashi Asano, Susumu Noda, Yasushi Takahashi
Optics Express 31 ( 9 ) 14317 - 14317 2023.4
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Ultrahigh-Q Photonic Nanocavity Devices on a Dual Thickness SOI Substrate Operating at Both 1.31-and 1.55-mu m Telecommunication Wavelength Bands Reviewed
Mitsuki Kuwabara, Susumu Noda, Yasushi Takahashi
LASER & PHOTONICS REVIEWS 13 ( 2 ) 2019.2
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Strongly asymmetric wavelength dependence of optical gain in nanocavity-based Raman silicon lasers Reviewed
Daiki Yamashita, Takashi Asano, Susumu Noda, Yasushi Takahashi
OPTICA 5 ( 10 ) 1256 - 1263 2018.10
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【Editors Pick】Ultrahigh-Q photonic crystal nanocavities fabricated by CMOS process technologies Reviewed
Kohei Ashida, Makoto Okano, Minoru Ohtsuka, Miyoshi Seki, Nobuyuki Yokoyama, Keiji Koshino, Masahiko Mori, Takashi Asano, Susumu Noda, Yasushi Takahashi
OPTICS EXPRESS 25 ( 15 ) 18165 - 18174 2017.7
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A micrometre-scale Raman silicon laser with a microwatt threshold Reviewed
Yasushi Takahashi, Yoshitaka Inui, Masahiro Chihara, Takashi Asano, Ryo Terawaki, Susumu Noda
NATURE 498 ( 7455 ) 470 - 474 2013.6
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Strong coupling between distant photonic nanocavities and its dynamic control Reviewed
Yoshiya Sato, Yoshinori Tanaka, Jeremy Upham, Yasushi Takahashi, Takashi Asano, Susumu Noda
NATURE PHOTONICS 6 ( 1 ) 56 - 61 2012.1
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【Editors Pick】Design and demonstration of high-Q photonic heterostructure nanocavities suitable for integration Reviewed
Yasushi Takahashi, Yoshinori Tanaka, Hiroyuki Hagino, Tomoyuki Sugiya, Yoshiya Sato, Takashi Asano, Susumu Noda
OPTICS EXPRESS 17 ( 20 ) 18093 - 18102 2009.9
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Detection of Charged Particles in a Vacuum Using a Photonic Crystal Waveguide Reviewed
Kosei Otsuka, Takeki Higashiguchi, Rikuto Hojo, Kazuya Kikunaga, Kazuhiro Toyoda, Yasushi Takahashi
2024 Conference on Lasers and Electro-Optics Pacific Rim (CLEO-PR) 1 - 2 2024.8
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Raman Scattering in a Silicon Photonic Nanocavity Operating at $1.1 \mu \mathrm{m}$ Reviewed
Yu Shimomura, Takashi Asano, Susumu Noda, Yasushi Takahashi
2023 IEEE Workshop on Recent Advances in Photonics (WRAP) 1 - 3 2023.12
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Stable Detection of Ionized Air by a Highly Excited Raman Silicon Nanocavity Laser Reviewed
Takeki Higashiguchi, Kousei Otsuka, Makoto Okano, Yasushi Takahashi
2023 IEEE Workshop on Recent Advances in Photonics (WRAP) 1 - 3 2023.12
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Silicon nanocavity with a quality factor of 6.7 million fabricated by a CMOS-compatible process Reviewed
Masaaki Katsura, Yuji Ota, Ryota Mitsuhashi, Minoru Ohtsuka, Miyoshi Seki, Nobuyuki Yokoyama, Takashi Asano, Susumu Noda, Makoto Okano, Yasushi Takahashi
Optics Express 31 ( 23 ) 37993 - 37993 2023.10
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Akari Fukuda, Takashi Asano, Taro Kawakatsu, Yasushi Takahashi, Susumu Noda
Optics Express 31 ( 10 ) 15495 - 15513 2023.4
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Control of the sensitivity of the detection of ionized air using photonic crystal waveguides
Masanao Fujimoto, Yuki Takahashi, Kazuya Kikunaga, Yasushi Takahashi
OPTICS CONTINUUM 2 ( 2 ) 349 - 360 2023.2
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Akari Fukuda, Takashi Asano, Yasushi Takahashi, Susumu Noda
2022 Conference on Lasers and Electro-Optics Pacific Rim (CLEO-PR) 1 - 2 2022.7
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Detection of ionized air using a photonic-crystal nanocavity excited by broadband light from a superluminescent diode
Yuki Takahashi, Masanao Fujimoto, Kazuya Kikunaga, Yasushi Takahashi
OPTICS EXPRESS 30 ( 7 ) 10694 - 10708 2022.3
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Yuji Ota, Makoto Okano, Yasushi Takahashi
Proceedings of the 2022 Conference on Lasers and Electro-Optics Pacific Rim CFA12F_02 - CFA12F_02 2022
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1.2-mu m-band ultrahigh-Q photonic crystal nanocavities and their potential for Raman silicon lasers
Hiroko Okada, Masanao Fujimoto, Natsumi Tanaka, Yuki Saito, Takashi Asano, Susumu Noda, Yasushi Takahashi
OPTICS EXPRESS 29 ( 15 ) 24396 - 24410 2021.7
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Detection of negatively ionized air by using a Raman silicon nanocavity laser
Satoshi Yasuda, Yuki Takahashi, Takashi Asano, Yuki Saito, Kazuya Kikunaga, Daiki Yamashita, Susumu Noda, Yasushi Takahashi
OPTICS EXPRESS 29 ( 11 ) 16228 - 16240 2021.5
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Sub-100-nW-threshold Raman silicon laser designed by a machine-learning method that optimizes the product of the cavity Q-factors
Taro Kawakatsu, Takashi Asano, Susumu Noda, Yasushi Takahashi
OPTICS EXPRESS 29 ( 11 ) 17053 - 17068 2021.5
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Design characteristics of a raman silicon nanocavity laser for efficient emission of light into an adjacent waveguide
Yuki Saito, Takashi Asano, Susumu Noda, Yasushi Takahashi
Optics InfoBase Conference Papers 2021
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Oscillation interruption of a raman silicon nanocavity laser induced by positively ionized-air irradiation
Yuki Takahashi, Satoshi Yasuda, Masanao Fujimoto, Takashi Asano, Kazuya Kikunaga, Susumu Noda, Yasushi Takahashi
Optics InfoBase Conference Papers 2021
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Raman silicon laser based on a nanocavity fabricated by photolithography
Takamasa Yasuda, Makoto Okano, Minoru Ohtsuka, Miyoshi Seki, Nobuyuki Yokoyama, Yasushi Takahashi
OSA CONTINUUM 3 ( 4 ) 814 - 823 2020.4
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Detrimental Fluctuation of Frequency Spacing Between the Two High-Quality Resonant Modes in a Raman Silicon Nanocavity Laser
Jun Kurihara, Daiki Yamashita, Natsumi Tanaka, Takashi Asano, Susumu Noda, Yasushi Takahashi
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS 26 ( 2 ) 2020.3
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Statistical evaluation of Q factors of fabricated photonic crystal nanocavities designed by using a deep neural network
Masahiro Nakada, Kengo Tanaka, Takashi Asano, Yasushi Takahashi, Susumu Noda
APPLIED PHYSICS EXPRESS 13 ( 1 ) 2020.1
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Raman Scattering Emission from a Silicon Photonic Nanocavity Excited by a Superluminescent Diode
Taro Kawakatsu, Daiki Yamashita, Takashi Asano, Susumu Noda, Yasushi Takahashi
14th Pacific Rim Conference on Lasers and Electro-Optics (CLEO PR 2020) 2020
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Implementing a Raman silicon nanocavity laser for integrated optical circuits by using a (100) SOI wafer with a 45-degree-rotated top silicon layer
Yukiko Yamauchi, Makoto Okano, Hiroaki Shishido, Susumu Noda, Yasushi Takahashi
OSA CONTINUUM 2 ( 7 ) 2098 - 2112 2019.7
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Utilizing Broadband Light From a Superluminescent Diode for Excitation of Photonic Crystal High-Q Nanocavities
Risa Shiozaki, Takahiro Ito, Yasushi Takahashi
JOURNAL OF LIGHTWAVE TECHNOLOGY 37 ( 10 ) 2458 - 2466 2019.5
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Photonic Crystal Nanocavities With an Average Q Factor of 1.9 Million Fabricated on a 300-mm-Wide SOI Wafer Using a CMOS-Compatible Process
Kohei Ashida, Makoto Okano, Takamasa Yasuda, Minoru Ohtsuka, Miyoshi Seki, Nobuyuki Yokoyama, Keiji Koshino, Koji Yamada, Yasushi Takahashi
JOURNAL OF LIGHTWAVE TECHNOLOGY 36 ( 20 ) 4774 - 4782 2018.10
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Lasing Dynamics of Optically-Pumped Ultralow-Threshold Raman Silicon Nanocavity Lasers
Daiki Yamashita, Yasushi Takahashi, Jun Kurihara, Takashi Asano, Susumu Noda
PHYSICAL REVIEW APPLIED 10 ( 2 ) 2018.8
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Progress of ultrahigh-Q optical nanocavities using a silicon photonic crystal
TAKAHASHI Yasushi, OKANO Makoto, ASANO Takashi, NODA Susumu
Oyo Buturi 87 ( 10 ) 749 - 753 2018
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Excitation wavelength dependence of a high-Q nanocavitybased Raman silicon laser Reviewed
Daiki Yamashita, Takashi Asano, Susumu Noda, Yasushi Takahashi
Optics InfoBase Conference Papers 2018 2018
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Yukiko Yamauchi, Makoto Okano, Susumu Noda, Yasushi Takahashi
CLEO Pacific Rim Conference Th1H.2 - Th1H.2 2018
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Enhanced radiative recombination rate for electron-hole droplets in a silicon photonic crystal nanocavity
Toshiyuki Ihara, Yasushi Takahashi, Susumu Noda, Yoshihiko Kanemitsu
PHYSICAL REVIEW B 96 ( 3 ) 2017.7
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Photonic crystal nanocavity with a Q factor exceeding eleven million
Takashi Asano, Yoshiaki Ochi, Yasushi Takahashi, Katsuhiro Kishimoto, Susumu Noda
OPTICS EXPRESS 25 ( 3 ) 1769 - 1777 2017.2
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Analysis of high-Q photonic crystal L3 nanocavities designed by visualization of the leaky components
Kenichi Maeno, Yasushi Takahashi, Tatsuya Nakamura, Takashi Asano, Susumu Noda
OPTICS EXPRESS 25 ( 1 ) 367 - 376 2017.1
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Improvement in the quality factors for photonic crystal nanocavities via visualization of the leaky components
Tatsuya Nakamura, Yasushi Takahashi, Yoshinori Tanaka, Takashi Asano, Susumu Noda
OPTICS EXPRESS 24 ( 9 ) 9541 - 9549 2016.5
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A sub-microwatt threshold Raman silicon laser using a high-Q nanocavity Reviewed
Daiki Yamashita, Yasushi Takahashi, Takashi Asano, Susumu Noda
2015 11th Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2015 4 2016.1
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Raman shift and strain effect in high-Q photonic crystal silicon nanocavity
Daiki Yamashita, Yasushi Takahashi, Takashi Asano, Susumu Noda
OPTICS EXPRESS 23 ( 4 ) 3951 - 3959 2015.2
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Breakthroughs in Photonics 2013: A Microwatt-Threshold Raman Silicon Laser
Yasushi Takahashi, Susumu Noda
IEEE PHOTONICS JOURNAL 6 ( 2 ) 2014.4
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Ultra-compact 32-channel drop filter with 100 GHz spacing
Yasushi Takahashi, Takashi Asano, Daiki Yamashita, Susumu Noda
OPTICS EXPRESS 22 ( 4 ) 4692 - 4698 2014.2
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Photonic crystal nanocavity with a Q-factor of similar to 9 million
Hiroshi Sekoguchi, Yasushi Takahashi, Takashi Asano, Susumu Noda
OPTICS EXPRESS 22 ( 1 ) 916 - 924 2014.1
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High-Q resonant modes in a photonic crystal heterostructure nanocavity and applicability to a Raman silicon laser
Yasushi Takahashi, Yoshitaka Inui, Masahiro Chihara, Takashi Asano, Ryo Terawaki, Susumu Noda
PHYSICAL REVIEW B 88 ( 23 ) 2013.12
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Ultralow-threshold Continuous-wave Raman Silicon Laser Using a Photonic Crystal High-Q Nanocavity
Yasushi Takahashi, Yoshitaka Inui, Takashi Asano, Susumu Noda
2013 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) 2013
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Ultrahigh-Q photonic crystal nanocavities in wide optical telecommunication bands
Ryo Terawaki, Yasushi Takahashi, Masahiro Chihara, Yoshitaka Inui, Susumu Noda
OPTICS EXPRESS 20 ( 20 ) 22743 - 22752 2012.9
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Statistical studies of photonic heterostructure nanocavities with an average Q factor of three million
Yuki Taguchi, Yasushi Takahashi, Yoshiya Sato, Takashi Asano, Susumu Noda
OPTICS EXPRESS 19 ( 12 ) 11916 - 11921 2011.6
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First Observation of Raman Scattering Emission from Silicon High-Q Photonic Crystal Nanocavities
Yasushi Takahashi, Ryo Terawaki, Masahiro Chihara, Takashi Asano, Susumu Noda
2011 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) 2011
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Observation of strong coupling between distant photonic nanocavities through a waveguide Reviewed
Yoshiya Sato, Yoshinori Tanaka, Jeremy Upham, Yasushi Takahashi, Takashi Asano, Susumu Noda
2010 23RD ANNUAL MEETING OF THE IEEE PHOTONICS SOCIETY 545 - 546 2010
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Effects of fluctuation in air hole radii and positions on optical characteristics in photonic crystal heterostructure nanocavities
Hiroyuki Hagino, Yasushi Takahashi, Yoshinori Tanaka, Takashi Asano, Susumu Noda
PHYSICAL REVIEW B 79 ( 8 ) 2009.2
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Increasing the Q Factor and Controlling the Resonant Wavelength of Photonic Crystal Nanocavities
Yasushi Takahashi, Tomoaki Sugiya, Shota Yamada, Yuki Taguchi, Takashi Asano, Susumu Noda
2009 CONFERENCE ON LASERS AND ELECTRO-OPTICS AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (CLEO/QELS 2009), VOLS 1-5 52 - + 2009
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Higher-order resonant modes in a photonic heterostructure nanocavity
Yasushi Takahashi, Yoshinori Tanaka, Hiroyuki Hagino, Takashi Asano, Susumu Noda
APPLIED PHYSICS LETTERS 92 ( 24 ) 2008.6
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Enhanced Light Emission from Silicon Photonic Crystal Nanocavity
Masayuki Fujita, Yoshinori Tanaka, Yasushi Takahashi, Susumu Noda
2008 5TH IEEE INTERNATIONAL CONFERENCE ON GROUP IV PHOTONICS 359 - 361 2008
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High-Q photonic nanocavity with a 2-ns photon lifetime
Yasushi Takahashi, Hiroyuki Hagino, Yoshinori Tanaka, Takashi Asano, Susumu Noda
2008 CONFERENCE ON LASERS AND ELECTRO-OPTICS & QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE, VOLS 1-9 3110 - 3111 2008
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High-Q nanocavity with a 2-ns photon lifetime
Yasushi Takahashi, Hiroyuki Hagino, Yoshinori Tanaka, Bong-Shik Song, Takashi Asano, Susumu Noda
OPTICS EXPRESS 15 ( 25 ) 17206 - 17213 2007.12
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Biexciton gain and the Mott transition in GaAs quantum wires
Yuhei Hayamizu, Masahiro Yoshita, Yasushi Takahashi, Hidefumi Akiyama
PHYSICAL REVIEW LETTERS 99 ( 16 ) 2007.10
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Room-temperature excitonic absorption in quantum wires Reviewed
Yasushi Takahashi, Yuhei Hayamizu, Hirotake Itoh, Masahiro Yoshita, Hidefumi Akiyama, Loren N. Pfeiffer, Ken W. West
APPLIED PHYSICS LETTERS 87 ( 22 ) 223119 - (1-3) 2005.11
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Strong photoabsorption by a single-quantum wire in waveguide-transmission spectroscopy Reviewed
Yasushi Takahashi, Yuhei Hayamizu, Hirotake Itoh, Masahiro Yoshita, Hidefumi Akiyama, Loren N. Pfeiffer, Ken W. West
APPLIED PHYSICS LETTERS 86 ( 24 ) 243101 - (1-3) 2005.6
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Imaging of emission patterns in a T-shaped quantum wire laser Reviewed
Yasushi Takahashi, Shinichi Watanabe, Masahiro Yoshita, Hirotake Itoh, Yuhei Hayamizu, Hidefumi Akiyama, Loren N. Pfeiffer, Ken W. West
APPLIED PHYSICS LETTERS 83 ( 20 ) 4089 - 4091 2003.11
MISC
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Ultra-high-Q nanocavity and its dynamic control
NODA Susumu, TANAKA Yoshinori, TAKAHASHI Yasushi, ASANO Takashi
Oyo Buturi 77 ( 2 ) 150 - 154 2008.2
Awards
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Optics Express Editor's pick
2025.4 Optica Demonstration of enhanced Raman scattering in high-Q silicon nanocavities operating below the silicon band-gap wavelength
Yu Shimomura, Takashi Asano, Ayumi Ishihara, Susumu Noda, and Yasushi Takahashi
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Optics Express Editor's pick
2023.4 Optica Raman silicon nanocavity laser with efficient light emission from the edge of an adjacent waveguide
Yuki Saito, Takashi Asano, Susumu Noda, and Yasushi Takahashi
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第13回関西支部貢献賞
2021.3 応用物理学会関西支部
高橋和
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丸文学術賞
2014.3 一般財団法人丸文財団
高橋和
Research Projects
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Elucidation of internal absorption loss for high-Q silicon nanocavities and the development of novel functional optical devices
Grant number：21H01373 2021.04 - 2024.03
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
高橋 和
Grant amount：\17290000 （ Direct expense: \13300000 、 Indirect expense：\3990000 ）
研究初年度は、当初計画に従って、シリコンナノ共振器の吸収損失の正体と消去メカニズムの解明を、近赤外低温カソードルミネッセンスによる欠陥分析、欠陥を消去する熱処理の最適化、顕微分光測定によるデバイス評価を三位一体で行い進めた。その結果、主要な3つの研究テーマ、①動作波長の短波化、②Q値向上、③CMOS互換プロセスで作製されたデバイスの機能拡張において、着実な進歩が得られた。
①初年度より、1.2 um帯においてシリコンラマンレーザ発振を確認することができた。これは、シリコンラマンレーザの最短波長となる。1.5 um帯のラマンレーザよりもQ値が低かったにも関わらず、同等の低い閾値が得られた。ラマンレーザの動作波長を短くすると、高性能化が可能なことが実証できた。当初計画を上回り、1.08 umで動作する高Q値ナノ共振器を作製して、2万以上のQ値を得た。シリコンのバンドギャップよりも高いエネルギーにおいて、1万以上の高Q値が得られたことは、シリコンフォトニクスの新たな可能性として重要である。
②ナノ共振器の最高Q値である1100万の更新はできなかった。しかしながら、熱処理を最適化することにより、CMOS互換プロセスで作製したナノ共振器の最高Q値を、250万から350万に更新することができた。大量作製が可能なCMOSプロセスで作製したナノ共振器でもこれほど高いQ値が得られたことにより、シリコンナノ共振器の応用が進むだろう。
③CMOS作製したシリコンラマンレーザの閾値も、熱処理を最適化することにより、従来の半分まで低減できた。レーザ発振するサンプルも、歩留まり50%以上で得られた。ラマンレーザの実用化研究を加速させる成果である。予想以上に研究が進んだため、CMOS作製したシリコンナノ共振器の応用範囲を広げるために、産業界で大きな問題となっている空間電荷を検知する研究を進めた。 -
Study on Raman gain induced by incoherent light in high quality photonic crystal devices
Grant number：18H01479 2018.04 - 2021.03
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
Takahashi Yasushi
Grant amount：\17550000 （ Direct expense: \13500000 、 Indirect expense：\4050000 ）
We have studied the application of a nanocavity Raman silicon laser. The Raman scattering spectra from the nanocavity excited by incoherent light are compared with the spectra excited by coherent light. Although promising results were obtained for the cw laser oscillation, it was not possible to inject a sufficient amount of light into the nanocavity for the cw oscillation with incoherent light. It is effective for Raman laser with incoherent light to decrease the laser threshold. We have designed the nanocavity with the higher Q factors by the machine learning, in which the threshold of a sub 100 microwatt threshold was obtained. This threshold is less than half of the conventional value. In addition, we have also realized the Raman silicon laser with a shorter wavelength band that can decrease the threshold by two times. As an unexpected results, we have demonstrated a promising application of the development for the space charge sensor with incoherent light excitation.
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Study for the optical gain and the lasing characteristics of high-Q nanocavity-based silicon Raman laser
Grant number：15H05428 2015.04 - 2018.03
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (A)
Takahashi Yasushi, NODA SUSUMU, KANEMITSU YOSHIHIKO, ASANO TAKASHI, OKANO MAKOTO, IHARA TOSHIYUKI
Grant amount：\24570000 （ Direct expense: \18900000 、 Indirect expense：\5670000 ）
The realization of silicon-based lasers will be important for the energy-saving human lives. In this project, the lasing mechanism for high-Q nanocavity-based Raman silicon laser was studied using the well-developed nano-fabrication technique and microscopic spectroscopy. We found that the dynamical resonance wavelength shift cause a detrimental effect for the laser performances. In addition, we developed a novel technique to investigate the excitation-wavelength dependence of the optical gain. We also measured the frequency difference, operating wavelength dependence, and temperature dependence. Based on these findings, structural improvement was added and as a result, the production yield and output power was increased.
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Integration of silicon photonic devices operating various wavelength bands
Grant number：15K13326 2015.04 - 2017.03
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
Takahashi Yasushi, NODA SUSUMU, ASANO TAKASHI
Grant amount：\4030000 （ Direct expense: \3100000 、 Indirect expense：\930000 ）
In this research, we challenged to fabricate a silicon-on-insulator (SOI) substrate with different thicknesses and to integrate the silicon photonics devices which operate with different wavelength bands.
In the first year, we developed a new process for thinning the silicon substrate with sub-nanometer precision. Subsequently, we fabricated a silicon substrate having different thicknesses.
In the second year, we fabricated two high-Q nanocavities on a SOI chip, which operate in the 1310 nm and 1550 nm bands. We achieved the Q values more than 2 million in both nanocavities. Furthermore, we succeeded in fabricating the two Raman silicon lasers on the chip, which worked in the 1310 nm and 1550 nm bands. This achievement is above the initial plan. The Q value of 2 million is difficult to achieve even with a single chip, and the Raman silicon laser is the most difficult device to fabricate. We will conduct the industrial transfer of these technologies. -
Improvements of silicon photonic crystal nanocavity and study on the enhanced nonlinear effect
Grant number：23686015 2011.04 - 2015.03
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (A)
TAKAHASHI Yasushi, NODA Susumu, ASANO Takashi
Grant amount：\27040000 （ Direct expense: \20800000 、 Indirect expense：\6240000 ）
The 1st target of this research is to improve the performance of the silicon photonic crystal nanocavities. Especially, I focused on increasing the Q factor and reducing the fluctuation of the resonant wavelength. The 2nd target is to investigate the mechanism of enhancement of the nonlinear effects in the high-Q nanocavities. For these 4 years, I have successfully increased the Q factor to 9 million from 2.5 million and reduced the fluctuation of resonant wavelength to 0.2 nm from a few nm. Furthermore, I have developed a continuous-wave Raman silicon laser using a high-Q nanocavity, with a cavity size of less than 10 micrometers and an unprecedented ultralow threshold of 1 microwatt. These achievements are attracting much attention.
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高Ｑ値シリコンフォトニック結晶ナノ共振器における誘導ラマン散乱の増強
Grant number：23104721 2011.04 - 2013.03
日本学術振興会 科学研究費助成事業 新学術領域研究(研究領域提案型)
高橋 和
Grant amount：\6760000 （ Direct expense: \5200000 、 Indirect expense：\1560000 ）
本課題では、高Q値シリコンナノ共振器における誘導ラマン散乱の増強の基礎学理を、共振器のQ値／波長／電磁界分布／対称性、競合する非線形効果まで考慮して、体系的に調べることを主目的としてきた。多くの非線形現象の中から、誘導ラマン散乱を選択した理由は、間接遷移型半導体であるシリコンにおいて、光増幅やレーザー発振を可能とする実用上魅力的な現象だからである。更に、単結晶シリコンは大きなラマン利得係数を持ち、微細加工技術が成熟している利点から研究遂行可能と考えた。
本年度は、ついに、シリコンラマンレーザーの室温連続発振に成功した。発振閾値は、１マイクロワットで、これはインテルのラマンレーザーの２万分の１である。さらに、デバイスサイズは１０万分の１程度である。これは、前身の公募研究から継続して行ってきた、「ナノ共振器における誘導ラマン散乱増強メカニズムの基礎学理」を確立できたことが大きい。特に、電磁界分布の対称性、空間分布、ラマンテンソル、結晶方位の４つのパラメーターが関わる複雑な増強メカニズムを正確に理解できたことが本年度の一番の成果である。その他、昨年度までの成果である、①共振器内の2つの共振モードの周波数差をシリコンのラマンシフトである15.6 THzに共鳴させる共振器構造、および周波数差の微調方法を確立したこと、②誘導ラマン散乱を測定するための顕微光学系を構築して、実際にラマン散乱の増強を高感度でスペクトル測定できたこと、③世界最高Q値を持つナノ共振器の作製方法を開発していたこと、④その光物性を根底から理解していたこと、以上４つの成果によりレーザー発振が達成できた。残念ながら、研究人材が不足していたため、予定していたポンププローブ測定は行うことができず、今後の課題として持ち越された。
なお、試料作製の一部と理論研究は、京都大学野田進研究室の協力を得て行った。 -
シリコンフォトニック結晶光ナノ共振器におけるラマン効果の増強に関する研究
Grant number：21104512 2009 - 2010
日本学術振興会 科学研究費助成事業 新学術領域研究(研究領域提案型)
高橋 和
Grant amount：\8450000 （ Direct expense: \6500000 、 Indirect expense：\1950000 ）
本課題は、LSIテクノロジーの更なる進化に重要と期待されているSiベースの光LSIチップにおいて、不可欠な構成要素と思われるSiレーザやSi光増幅器を念頭に置いて、高Q値シリコン(Si)フォトニック結晶光ナノ共振器におけるラマン効果増強を実証することを目的とした。平成22年度は21年度に得られた成果を発展させて(1)ナノ共振器の動作波長を1.25μm以下まで拡大、(2)Q値に比例したラマン散乱光の増強を確認、(3)最高Q値を430万まで更新、(4)2つの高Q共振モードの周波数差をSiのラマンシフトである15.6THzに一致させる技術開発という4つの成果を得た。以下にその重要性と意義を記す。尚、主な論文発表は23年度に行ってゆくこととなる。
(1)Siフォトニクスの応用範囲を広げていくには、様々な波長で動作するナノ共振器が必要である。21年度にQ値100万以上を持つナノ共振器の動作波長を1.55μmから、1.37μmまで短波化したが、それ以上の短波化は技術的に困難だった。今回、独自にSOI基板薄膜化プロセスを開発して、その動作波長域を1.25μmまで拡大することに成功した。測定の都合でこれ以上短波化した試料を調べられなかったが作製は可能と思われる。
(2)Q値100万を持つSiナノ共振器からのストークスラマン散乱が、フォトニック結晶導波路を用いる場合に比べ4桁低い励起強度、2桁以上高い効率で起こることを観測した。また、この増強はQ値に比例することも確認した。更に、Siラマンレーザへの利用が期待される高次エネルギーモードからも散乱光を観測した。これらは、省電力Siラマンレーザ開発に繋がる成果である。
(3)ナノ共振器におけるラマン効果増強に肝要となるナノ共振器の世界最高Q値をこれまでの360万から430万まで向上することに成功した。日本以外のグループで100万以上の報告はない。
(4)ナノ共振器中の複数の高Qナノ共振モードの周波数差を15.6THzに拡げることに成功するとともに、周波数差の微徴技術を開発した。 -
Dynamic control of photonic crystal for new functionality
Grant number：20226002 2008 - 2012
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)
NODA Susumu, ASANO Takashi, TANAKA Yoshinori, TAKAHASHI Yasushi
Grant amount：\208130000 （ Direct expense: \160100000 、 Indirect expense：\48030000 ）
The target of this project is to dynamically control photonic crystals to create new functionalities, and to develop a new academic field called: “ Dynamic Photonic Crystal”. We have successfully demonstrated that
(1) an optical pulse can be held effectively, and can be rapidly released on demand by the dynamic control of the Q factor of the photonic crystal nanocavity , and
(2) t he dynamic change of the characteristics of photonic crystal waveguides produces dynamic charact eristic and behavior changes of photons propagating in the photonic crystals.