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Conference on Lasers and Electro-Optics, CLEO 2002

作者： Fang, Xiaojun Adachi, Muneyuki Karasawa, Naoki Morita, Ryuji Yamashita, Mikio Windeler, Robert S. Department of Applied Physics Hokkaido University Core Research for Evolutional Science and Technology Japan Science and Technology Corporation Kita-13 Nishi-8 Kita-ku Sapporo060-8628 Japan Bell Laboratories Lucent Technologies 700 Mountain Avenue Murray HillNJ070974 United States

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Experimental and theoretical studies on nonlinear propagation of a-few-optical-cycle pulses in a photoniccrystal fiber -beyond the slowly-varying-envelope approximation-

Experimental and theoretical studies on nonlinear propagatio...

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International Conference on Ultrafast Phenomena, UP 2002

作者： Fang, Xiaojun Hirasawa, Masakatsu Morita, Ryuji Yamashita, Mikio Windeler, Robert S. Department of Applied Physics Hokkaido University Core Research for Evolutional Science and Technology Japan Science and Technology Corporation Kita-13 Nishi-8 Kita-ku Sapporo060-8628 Japan Bell Laboratories Lucent Technologies 700 Mountain Avenue Murray HillNJ070974 United States

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Exciton-biexciton dynamics in an organic-inorganic hybrid quantum-well material

Exciton-biexciton dynamics in an organic-inorganic hybrid qu...

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Quantum Electronics and Laser science Conference (QELS)

作者： Kato Ichii Ohashi Kunugita Ema Tanaka Takahashi Kondo Core Research for Evolutional Science and Technology (CREST) Japan Science and Technology Corporation (JST) Department of Physics Sophia University Tokyo Japan Core Research for Evolutional Science and Technology (CREST) Japan Science and Technology Corporation (JST) Japan Department of Material Science The University of Tokyo Tokyo Japan

Summary form only given. Excitonic optical properties have been extensively studied in a large variety of semiconductors, and it has been found that biexciton formation and relaxation play an important role in the nonlinear optical processes. The binding energies of biexcitons in typical semiconductors, however, are less than 10 meV so that it is difficult in femtosecond spectroscopy to distinguish the biexciton process from a single exciton process. In order to study the exciton-biexciton system in detail, a large binding energy of the biexciton is required. In this paper we report on the biexcitons with extremely large binding energy (= 66 meV) in an organic-inorganic hybrid quantum-well material, (C/sub 4/H/sub 9/NH/sub 3/)/sub 2/PbBr/sub 4/. This material belongs to the layered perovskite-type quantum-well materials (C/sub n/H/sub 2n+1/NH/sub 3/)/sub 2/PbX/sub 4/ which have excitons with large binding energy. We investigate the dynamics of such a stable exciton-biexciton system.

关键词： Excitons Quantum wells Photoluminescence

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Experimental and theoretical investigation on nonlinear 4.5-optical-cycle-pulse propagation in photonic crystal fibers

Experimental and theoretical investigation on nonlinear 4.5-...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Xiaojun Fang M. Adachi N. Karasawa R. Morita M. Yamashita R.S. Windeler Department of Applied Physics Hokkaido University Core Research for Evolutional Science and Technology Japan Science and Technology Corporation Sapporo Japan Bell Laboratories Lucent Technologies Inc. NJ USA

Summary form only given. In this paper, we demonstrate the experimental evolution of ultra-broad spectra generated by photonic crystal fibers (PCFs) of different lengths, and theoretically analyze the nonlinear process based on our derived nonlinear propagation equation beyond the slowly-varying-envelope approximation (SVEA). The calculated results of the complicated frequency-dependent phase are significantly useful for extremely flexible and accurate active-chirp compensation by a 4-f pulse shaper with a spatial phase modulator for monocycle-pulse generation.

关键词： Optical pulse generation Photonic crystal fibers Optical pulses Supercontinuum generation Numerical simulation Autocorrelation Optical propagation Nonlinear equations Microstructure Pulse measurements

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Electric-field effect on 2s excitons of a natural-quantum-well crystal (C6H13NH3)2PbI4

Electric-field effect on 2s excitons of a natural-quantum-we...

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Nonlinear Optics: Materials, Fundamentals and Applications, NLO 2002

作者： Tanaka, Kenichiro Nabeshima, Yasuo Kondo, Takashi Ito, Ryoichi Ema, Kazuhiro Department of Materials Science The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Japan Department of Physics Meiji University 1-1-1 Higashi-Mita Tama-ku Kanagawa Kawasaki214-8571 Japan Department of Physics Sophia University 7-1 Kioi-cho Chiyoda-ku Tokyo102-8554 Japan Core Research for Evolutional Science and Technology Japan Science and Technology Corporation Japan

Unusual blue shift was observed on quantum-confined 2s exciton in a natural-quantum-well crystal (C6H13NH3)2PbI4 under the longitudinal electric field. This is attributed to the mixing of the 2s state with the triplet... 详细信息

ISBN: (纸本)1557527210

关键词： Excitons

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Characterization and compression of femtosecond optical pulses nonlinearly propagated in a tapered fiber

Characterization and compression of femtosecond optical puls...

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Conference on Lasers and Electro-Optics (CLEO)

作者： M. Adachi Xiaojun Fang N. Nakagawa M. Hirasawa A. Suguro N. Karasawa S. Kobayashi M. Kasamatsu R. Morita M. Yamashita Department of Applied Physics Hokkaido University and Laser Research Laboratory NIDEK Company Limited Gamagori Aichi Japan Department of Applied Physics Hokkaido University Core Research for Evolutional Science and Technology Japan Science and Technology Corporation Sapporo Japan CITIZEN WATCH Company Limited Tokorozawa Saitama Japan Department of Applied Photonics System Technology Chitose Institute of Science and Technology Chitose Hokkaido Japan NIDEK Company Limited Gamagori Aichi Japan

Summary form only given. A tapered-silica fiber has recently been used in producing an ultra-broad band spectrum. By heating and stretching a 10 mm silica fiber with a 125 /spl mu/m outer diameter and a 9 /spl mu/m core diameter, a 70 mm totally long tapered fiber was produced with a 25 mm long waist of 2 /spl mu/m uniform diameter. A typical resultant ultra-broad band spectrum was found to range from 425 to 955 nm. By using our second-harmonic frequency-resolved optical gating (SH-FROG) apparatus, the intensity and phase profiles of the output pulse from the fiber in both temporal and frequency domains were determined. The output pulse was centered at 785 nm and had an averaged power of 26 mW for the input with a 150 fs duration. We performed pulse compression with a liquid crystal spatial light modulator (SLM) on the basis of the spectrum phase information obtained by the SH-FROG measurement. This was the first pulse compression of an output pulse from a tapered fiber using an SLM. That is, chirp compensation of the complicated frequency-dependent phase in comparison with that of the conventional silica-fiber output was carried out successfully by the spatial light modulation technique for the first time.

关键词： Ultrafast optics Optical pulses Optical propagation Frequency Optical pulse compression Phase modulation Chirp modulation Optical modulation Pulse compression methods Heating

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Deterministic SR phenomena in autoassociative chaotic neural networks

Deterministic SR phenomena in autoassociative chaotic neural...

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International Conference on Neural Information Processing

作者： H. Nishimura N. Katada K. Aihara Studies of Information Science Hyogo University of Education Yashiro Hyogo Japan Department of Mathematical Engineering and Information Physics Graduate School of Engineering University of Tokyo Bunkyo Tokyo Japan Core Research for Evolutional Science and Technology Japan Science and Technology Corporation Kawaguchi Saitama Japan

In the previous works, we have set up a signal-driven scheme of the neural network with the coupling constants corresponding to certain information, and investigated the SR (stochastic resonance)-like effects under the aperiodic stored/non-stored pattern signals, comparing the deterministic case with the conventional case of the Hopfield network with stochastic noise. In this paper, we focus on deterministic SR-type responses in a simple system which consists of three neurons. This case is considered as a effective double-well model with chaotic dynamics. We demonstrate that SR-like effect can be enhanced by modulating the control parameter (bias strength) for a periodic input signal, in the phases of intermittency of chaos-chaos type.

关键词： Strontium Intelligent networks Chaos Neural networks Stochastic resonance Neurons Hopfield neural networks Stochastic systems Educational technology Acoustical engineering

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Ab initio study of field evaporation from single-walled carbon nanotubes

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Physical Review B 2002年第15期65卷 155424-155424页

作者： N. Nakaoka K. Watanabe Department of Physics Tokyo University of Science 1-3 Kagurazaka Shinjuku-ku Tokyo 162-8601 Japan Core Research for Evolutional Science and Technology (CREST) Japan Science and Technology Corporation 4-1-8 Honmachi Kawaguchi Saitama 332-0012 Japan Frontier Research Center for Computational Sciences Tokyo University of Science 1-3 Kagurazaka Shinjuku-ku Tokyo 162-8601 Japan

We have performed partitioned real-space density functional (PRDF) calculations of field evaporation of carbon clusters from single-walled carbon nanotubes (SWNT). The calculation results of the activation-energy barrier (AEB) for field evaporation of carbon clusters and hydrocarbon clusters from SWNT’s show that the AEB decreases as the electric field increases, and that the atom-relaxation effect largely reduces the AEB. It is also found that evaporation from an open-ended carbon nanotube occurs more easily than from capped nanotubes owing to the difference in the number of C-C bonds between the two types of nanotubes. Most surprisingly, adsorbed hydrogen significantly reduces the AEB. This is clearly explained by the C-C bond weakening due to the adsorbed hydrogen.

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Temporal changes in testis weight during the past 50 years in Japan

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Anatomical science international / Japanese Association of Anatomists 2002年第2期77卷 109-116页

作者： Mori, Chisato Hamamatsu, Akihiko Fukata, Hideki Koh, Kyu-Bom Nakamura, Noriko Takeichi, Sanae Kusakabe, Takahiko Saito, Takeshi Morita, Masatoshi Tanihara, Shinichi Kayama, Fujio Shiyomi, Masae Yoshimura, Jin Sagisaka, Kaoru Department of Bioenvironmental Medicine Graduate School of Medicine Chiba University Chiba 260-8670 1-8-1 Inohana Chuo-ku Japan Core Research for Evolutional Science and Technology Japan Science and Technology Corporation Kawaguchi Japan Tokyo Medical Examiner’s Office Tokyo Japan Department of Anatomy and Molecular Cell Biology Graduate School of Medicine Nagoya University Nagoya Japan Department of Forensic Medicine Tokai University School of Medicine Kanagawa Japan Division of Chemistry and Physics National Institute for Environmental Studies Tukuba Ibaragi Japan Department of Public School Jichi Medical School Tochigi Japan Department of Environmental Health Jichi Medical School Tochigi Japan Department of Environmental Sciences Faculty of Science Ibaraki University Mito Japan Department of Systems Engineering Shizuoka University Hamamatsu Shizuoka Japan NERC Center for Population Biology Imperial College at Silwood Park Ascot Berks United Kingdom

The ever-increasing presence of environmental toxicants and their disruptive effect on the reproductive systems of wildlife raises the question of possible damage to the human reproductive system. Using medicolegal data from over 20,000 Japanese men subjected to necropsy from 1948 to 1998, we investigated temporal changes in testis weight to find possible evidence of male reproductive disorders. We also carried out a histological examination of 747 testes collected from 1978 to 1998. Our detailed analyses of the development of testis weight over the past 50 years have revealed four clear phenomena: (i) the age at which testis weight reaches its maximum has decreased;(ii) peak weight showed a general increase until it started to decline in boys born after 1960;(iii) the decline-rate at which testis weight decreases after its peak has greatly accelerated;and (iv) the onset of increasing testis weight of boys has occurred at a progressively younger age. Our quantitative analyses of testis weight indicate the possibility of a subtle reproductive disorder in Japanese men, especially in those born after 1960. Together with the accelerated development and decline in testis weight during the past 50 years, the decline in peak weight might be indicative of a subtle interference of environmental toxicants with male reproductive organogenesis.

关键词： human Japan male reproductive disorder testis weight

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Photoconductivity and Local Transport Properties of Single‐Wall Carbon Nanotubes

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AIP Conference Proceedings 2002年第1期633卷 247-250页

作者： A. Fujiwara Y. Matsuoka R. Iijima H. Suematsu N. Ogawa K. Miyano H. Kataura Y. Maniwa S. Suzuki Y. Achiba School of Materials Science Japan Advanced Institute of Science and Technology 1‐1 Asahidai Tatsunokuchi Ishikawa 923‐1292 Japan Core Research for Evaluational Science and Technology (CREST) Japan Science and Technology Corporation (JST) Department of Physics School of Science University of Tokyo 7‐3‐1 Hongo Bunkyo‐ku Tokyo 113‐0033 Japan Department of Applied Physics School of Engineering University of Tokyo 7‐3‐1 Hongo Bunkyo‐ku Tokyo 113‐8656 Japan Research Center for Advanced Science and Technology University of Tokyo 4‐6‐1 Komaba Meguro‐ku Tokyo 153‐8904 Japan Department of Physics School of Science Tokyo Metropolitan University 1‐1 Minami‐osawa Hachi‐oji Tokyo 192‐0397 Japan Department of Chemistry School of Science Tokyo Metropolitan University 1‐1 Minami‐osawa Hachi‐oji Tokyo 192‐0397 Japan

Photoconducting and local transport properties of single‐wall carbon nanotubes (SWNTs) have been investigated. Two peaks in the photoconductivity excitation spectra around 0.7 and 1.2 eV are observed at room temperature, which can be interpreted as a photocurrent in semiconducting SWNTs. From the local transport measurements on SWNT bundles by the combination of atomic force microscopy and scanning tunneling spectroscopy, we find current flows through each SWNT separately rather than uniformly in the bundle. The results show that we can extract the transport properties of semiconducting or metallic SWNTs from the mixture of both phases by photoconductivity measurements and the local transport measurements.

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