論文 - 藤原　正澄

Four-wave mixing signals from beta-carotene and its n=15 homologue 査読

Mitsuru Sugisaki, Masazumi Fujiwara, Kazuhiro Yanagi, Richard J. Cogdell, Hideki Hashimoto

PHOTOSYNTHESIS RESEARCH   95 ( 2-3 )   299 - 308   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：SPRINGER  

The third-order nonlinear optical responses of beta-carotene and its homologue having a conjugation-double bond n = 15 have been investigated using sub-20 fs ultra-short optical pulses in order to clarify the dissipation processes of excess energy. Using the four-wave mixing spectroscopy, we observed a clear coherent oscillation with a period of a few tens of femtoseconds. The spectral density of these molecules was estimated that allowed the theoretical linear and nonlinear optical signals to be directly compared with the experimental data. Calculations based on the Brownian oscillator model were performed under the impulsive excitation limit. We show that the memory of the vibronic coherence generated upon the excitation into the S-2 state is lost via the relaxation process including the S-1 state. The vibronic decoherence lifetime of the system was estimated to be 1 ps, which is about 5 times larger than the life time of the S-2 state (similar to 150 fs) determined in previous studies. The role of coherence and the efficient energy transfer in the light-harvesting antenna complexes are discussed.

DOI： 10.1007/s11120-007-9265-y

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Widely tunable terahertz-wave generation using an N-benzyl-2-methyl-4-nitro aniline crystal 査読

Katsuhiko Miyamoto, Hiroaki Minamide, Masazumi Fujiwara, Hideki Hashimoto, Hiromasa Ito

OPTICS LETTERS   33 ( 3 )   252 - 254   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：OPTICAL SOC AMER  

Widely tunable terahertz (THz)-wave generation using difference frequency generation (DFG) in an organic N-benzyl-2-methyl-4-nitroaniline (BNA) crystal was demonstrated. To our knowledge, this is the first report of THz-wave generation by BNA DFG. Large, high-quality single crystals of BNA (0 8 mm X 30 mm) were grown using the vertical Bridgman method. The nonlinear optical (NLO) coefficient d(33) of the BNA crystal is similar to 234 pm/V, which is the largest value reported for any yellow NLO material. The collinear phase-matching condition of the type-0 configuration is satisfied using a 0.7-1 mu m band pump wavelength. We generated THz waves using an organic BNA crystal; the generation range is 0.1-15 THz. (C) 2008 Optical Society of America.

DOI： 10.1364/OL.33.000252

DOI： 10.1364/ol.33.000252

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Four-wave mixing signals from beta-carotene and its n=15 homologue 査読

Mitsuru Sugisaki, Masazumi Fujiwara, Kazuhiro Yanagi, Richard J. Cogdell, Hideki Hashimoto

PHOTOSYNTHESIS RESEARCH   95 ( 2-3 )   299 - 308   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：SPRINGER  

The third-order nonlinear optical responses of beta-carotene and its homologue having a conjugation-double bond n = 15 have been investigated using sub-20 fs ultra-short optical pulses in order to clarify the dissipation processes of excess energy. Using the four-wave mixing spectroscopy, we observed a clear coherent oscillation with a period of a few tens of femtoseconds. The spectral density of these molecules was estimated that allowed the theoretical linear and nonlinear optical signals to be directly compared with the experimental data. Calculations based on the Brownian oscillator model were performed under the impulsive excitation limit. We show that the memory of the vibronic coherence generated upon the excitation into the S-2 state is lost via the relaxation process including the S-1 state. The vibronic decoherence lifetime of the system was estimated to be 1 ps, which is about 5 times larger than the life time of the S-2 state (similar to 150 fs) determined in previous studies. The role of coherence and the efficient energy transfer in the light-harvesting antenna complexes are discussed.

DOI： 10.1007/s11120-007-9265-y

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Coherent tunable monochromatic Terahertz-wave generation using N-Benzyl-2-methyl-4-nitroaniline (BNA) crystal 査読

Katsuhiko Miyamoto, Hiroaki Minamide, Masazumi Fujiwara, Hideki Hashimoto, Hiromasa Ito

NONLINEAR FREQUENCY GENERATION AND CONVERSION: MATERIALS, DEVICES, AND APPLICATIONS VII   6875   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  

Widely tunable terahertz (THz) -wave generation using difference frequency generation (DFG) in an organic N-Benzyl-2-methyl-4-nitroaniline (BNA) crystal was demonstrated. An organic nonlinear optical (NLO) BNA crystal is one of the promising materials for efficient and strong THz-wave generation because of its potential to have a sufficiently large enough second-order optical nonlinearity. Large and high quality single crystals of BNA (phi 8x30mm) were successfully grown by a vertical Bridgman method. The NLO coefficient d(33) of BNA crystal is about 230pm/V. It is the largest value reported for any yellow-colored NLO materials. BNA has low refractive index dispersion between the optical and THz-wave region, therefore the colinear phase matching condition of the Type0 configuration is satisfied by using 0.7 similar to 1 mu m band pump wavelength. So, we developed a near-infrared dual-wavelength pump source for BNA-DFG. Two KTiOPO4 (KTP) crystals were mounted on galvano scanners inside a double-pass optical parametric oscillator (OPO). It is pumped using a frequency-doubled Nd:YAG laser (532 nm, 8 ns, 100 Hz). The signal wave of the KTP-OPO output was controlled independently and rapidly using a galvano scanner. We successfully generated THz-wave using organic BNA crystal. The THz-wave generation range is from 0.1 to 15THz, while the pumping dual-wavelength is controlled in the 0.8-0.9 mu m range.

DOI： 10.1117/12.762620

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Determination of the d-tensor components of a single crystal of N-benzyl-2-methyl-4-nitroaniline 査読

Masazumi Fujiwara, Minoru Maruyama, Mitsuru Sugisaki, Hironori Takahashi, Shin-ichiro Aoshima, Richard J. Cogdell, Hideki Hashimoto

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   46 ( 4A )   1528 - 1530   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：INST PURE APPLIED PHYSICS  

Linear and second-order nonlinear optical (NLO) properties of a single crystal of N-benzyl-2-methyl-4-nitroaniline (BNA) have been determined. The refractive indices of the crystal were measured in the visible to near infra-red region. The Maker-fringe and phase-matching methods were used to determine the magnitudes of the d-tensor components for the second harmonic generation when excited the crystals at 1064 nm. They were d(333) = 234 +/- 31, d(322) = 15.6 +/- 0.9, and d(311) similar to 0 pm/V. The value of d(333) is the largest value reported for any yellow-colored NLO materials and suggests that crystals of BNA will be very effective for terahertz wave generation.

DOI： 10.1143/JJAP.46.1528

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Second order nonlinear optical properties of the single crystal of N-benzyl 2-methyl-4-nitroaniline: Anomalous enhancement of the d(333) component and its possible origin 査読

Masazumi Fujiwara, Kazuhiro Yanagi, Minoru Maruyama, Mitsuru Sugisaki, Kazuyoshi Kuroyanagi, Hironori Takahashi, Shin-ichiro Aoshima, Yutaka Tsuchiya, Andrew Gall, Hideki Hashimoto

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   45 ( 11 )   8676 - 8685   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：JAPAN SOC APPLIED PHYSICS  

A single crystal of N-benzyl 2-methyl-4-nitroaniline (BNA) whose dimensions were 8 x 10 mm (diameter x length) was grown using a vertical Bridgman method with sufficient optical transparency for spectroscopic use. Polarized reflection spectra of the crystal were measured in order to determine its linear optical parameters (refractive indices and extinction coefficients). The relative magnitudes of the d-tensor components of the crystal were determined to be d(333) = (17 +/- 9) x d(322,) d(322) > d(311), d(311) similar to 0 from polarization dependencies of the second harmonic generation. These results are in disagreement with previously reported theoretical studies, in which the effects of intermolecular interactions were completely neglected. Here, we have included these intermolecular interactions in the calculations assuming the presence of supra-molecular clusters. We conclude that the anomalous enhancement of d(333) is due to the interactions along the direction of the hydrogen bonds in the crystal and the resonance effect.

DOI： 10.1143/JJAP.45.8676

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Second order nonlinear optical properties of the single crystal of N-benzyl 2-methyl-4-nitroaniline: Anomalous enhancement of the d(333) component and its possible origin 査読

Masazumi Fujiwara, Kazuhiro Yanagi, Minoru Maruyama, Mitsuru Sugisaki, Kazuyoshi Kuroyanagi, Hironori Takahashi, Shin-ichiro Aoshima, Yutaka Tsuchiya, Andrew Gall, Hideki Hashimoto

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   45 ( 11 )   8676 - 8685   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：JAPAN SOC APPLIED PHYSICS  

A single crystal of N-benzyl 2-methyl-4-nitroaniline (BNA) whose dimensions were 8 x 10 mm (diameter x length) was grown using a vertical Bridgman method with sufficient optical transparency for spectroscopic use. Polarized reflection spectra of the crystal were measured in order to determine its linear optical parameters (refractive indices and extinction coefficients). The relative magnitudes of the d-tensor components of the crystal were determined to be d(333) = (17 +/- 9) x d(322,) d(322) > d(311), d(311) similar to 0 from polarization dependencies of the second harmonic generation. These results are in disagreement with previously reported theoretical studies, in which the effects of intermolecular interactions were completely neglected. Here, we have included these intermolecular interactions in the calculations assuming the presence of supra-molecular clusters. We conclude that the anomalous enhancement of d(333) is due to the interactions along the direction of the hydrogen bonds in the crystal and the resonance effect.

DOI： 10.1143/JJAP.45.8676

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Determination of refractive indices and absorption coefficients of highly purified N-benzyl-2-methyl-4-nitroaniline crystal in terahertz frequency regime 査読

Kazuyoshi Kuroyanagi, Masazumi Fujiwara, Hideki Hashimoto, Hironori Takahashi, Shin-ichiro Aoshima, Yutaka Tsuchiya

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   45 ( 29-32 )   L761 - L764   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：INST PURE APPLIED PHYSICS  

We have measured the refractive index and absorption coefficient of the N-benzyl-2-methyl-4-nitroaniline crystal using terahertz time-domain spectroscopy. We found that the refractive index had a value between 1.5 and 1.9 in the (100) direction and between 1.9 and 2.3 in the (100) direction. We also found that there were resonances at 1.6 and 3.2 THz in the (100) direction, and 1.3, 2.2, and 3.6 THz in the (001) direction within the observed spectral range between 0 and 5 THz. A Lorentz-type oscillator model is applicable to explain our experimental observations.

DOI： 10.1143/JJAO.45.L761

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All organic terahertz electromagnetic wave emission and detection using highly purified N-benzyl-2-methyl-4-nitroaniline crystals 査読

K Kuroyanagi, M Fujiwara, H Hashimoto, H Takahashi, SI Aoshima, Y Tsuchiya

JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   45 ( 5A )   4068 - 4073   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：INST PURE APPLIED PHYSICS  

We studied terahertz (THz) electromagnetic wave emission and detection using highly purified N-benzyl-2-methyl-4-nitroaniline (BNA) crystals. In THz emission experiments, we compared the efficiencies of THz emission via optical rectification for BNA, ZnTe, and GaP crystals, and confirmed that the BNA crystal is the most efficient THz emitter among these three crystals within the frequency range limits for observation. In the THz detection experiment, we also compared the modulation efficiencies of the BNA and ZnTe crystals, and found that the ZnTe crystal has a higher efficiency than the BNA crystal. However, the BNA crystal has a higher efficiency than the ZnTe crystal in high-frequency regions. Since the BNA crystal is suitable for detecting a high-frequency region even when using thick crystals, it is expected that the BNA crystal as a THz detector will be easy to prepare and handle.

DOI： 10.1143/JJAP.45.4068

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