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塩田 達俊
| 理工学研究科 数理電子情報部門 | 准教授 |
| 工学部 電気電子物理工学科 |
業績情報
■ 論文- Nonlinear polarization rotation based 635 nm praseodymium doped mode-locked fiber laser
Nasrin Sultana; Masanori Nishiura; Tatsutoshi Shioda
Applied Physics Express, 巻：17, 号：11, 開始ページ：112002, 終了ページ：112002, 2024年11月
Abstract
We demonstrated a mode-locked fiber laser oscillator using nonlinear polarization rotation as a saturable absorption system. The fiber laser generates mode-locked pulses by adjusting four waveplates. A single-clad Pr3+-doped single mode fluoride fiber with a 425 mW threshold pump power serves as the foundation for the ring cavity, which operates in the dissipative soliton resonance regime. The radio frequency signal-to-noise ratio of the pulses at 634.9 nm is 60 dB, maximum output power of 5.5 mW, and repetition rate of 34.5 MHz. These findings provide a foundation for the advancement of photonic applications in the visible spectrum.
IOP Publishing, 研究論文（学術雑誌）
DOI：https://doi.org/10.35848/1882-0786/ad8a15
DOI ID：10.35848/1882-0786/ad8a15, ISSN：1882-0778, eISSN：1882-0786 - Rapid optical tomographic vibrometry using a swept multi-gigahertz comb
Samuel Choi; Takeru Ota; Fumiaki Nin; Tatsutoshi Shioda; Takamasa Suzuki; Hiroshi Hibino
Optics Express, 巻：29, 号：11, 開始ページ：16749, 終了ページ：16749, 2021年05月, ［国際誌］
We propose a rapid tomographic vibrometer technique using an optical comb to measure internal vibrations, transient phenomena, and tomographic distributions in biological tissue and microelectromechanical system devices at high frequencies. This method allows phase-sensitive tomographic measurement in the depth direction at a multi-MHz scan rate using a frequency-modulated broadband electrooptic multi-GHz supercontinuum comb. The frequency spacing was swept instantaneously in time and axisymmetrically about the center wavelength via a dual-drive Mach-Zehnder modulator driven by a variable radio frequency signal. This unique sweeping method permits direct measurement of fringe-free interferometric amplitude and phase with arbitrarily changeable measurement range and scan rate. Therefore, a compressive measurement can be made in only the depth region where the vibration exists, reducing the number of measurement points. In a proof-of-principle experiment, the interferometric amplitude and phase were investigated for in-phase and quadrature phase-shifted interferograms obtained by a polarization demodulator. Tomographic transient displacement measurements were performed using a 0.12 mm thick glass film and piezo-electric transducer oscillating at 10-100 kHz with scan rates in the range 1-20 MHz. The depth resolution and precision of the vibrometer were estimated to be approximately 25 µm and 1.0 nm, respectively.
The Optical Society, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1364/oe.425972
DOI ID：10.1364/oe.425972, eISSN：1094-4087, PubMed ID：34154231 - 25.6a tbps pre-compensated waveform propagation using optical frequency comb synthesizer/analyzer
Nasrin Sultana; Hiroaki Tada; Hayate Imai; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 2021年
A scanless dispersion pre-compensation system for an ultrafast 25.6 waveform using multilevel 8-ary amplitude and 32-ary phase modulation was controlled and compensated by a 200 GHz optical frequency comb synthesizer with a 6.4 THz bandwidth.
The Optical Society, 英語, 研究論文（国際会議プロシーディングス）
SCOPUS ID：85119449285 - Dispersion pre-compensation of 25.6 Tbps waveforms using an optical frequency comb synthesizer/analyzer
Nasrin Sultana; Hiroaki Tada; Hayate Imai; Tatsutoshi Shioda
Optics Communications, 巻：475, 2020年11月
© 2020 In this study, we propose and demonstrate a dispersion compensation system for an ultrafast 25.6 Tbps waveform using multilevel 8-ary amplitude and 32-ary phase modulation. The waveform bit period was 312.5 fs, which was controlled and compensated by a 200 GHz optical frequency comb (OFC) synthesizer with a 6.4 THz bandwidth. Dispersion spectra were measured in parallel and simultaneously (within 1 ms), based on single-shot dual-heterodyne mixing by introducing an OFC and arrayed waveguide grating to separate sidebands. An optical pulse synthesizer (OPS) can individually control the phase and amplitude spectra of the OFC. To control transmitted waveforms in a dispersed media, the OPS can be oppositely biased to feed the measured dispersion back into the source waveform when it generates an arbitrary waveform. In this study, a 25.6 Tbps dispersion-free waveform was successfully transmitted through a 10.55 km fiber.
研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.optcom.2020.126196
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DOI ID：10.1016/j.optcom.2020.126196, ISSN：0030-4018, SCOPUS ID：85087200712 - 2D Single-shot Optical Coherence Tomography under Vibration Environment
Toshiki Awane; Tatsutoshi Shioda
2020 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2020 - Proceedings, 2020年08月
We demonstrated the performance of 2D single-shot tomography system for vibrating sample. The frequency dependence was investigated with the camera shutter speed of \\sim 1 \\mu \\mathrm{s}, which is faster than conventional OCT.
Institute of Electrical and Electronics Engineers Inc., 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/CLEOPR.2020.C10F_4
DOI ID：10.1364/CLEOPR.2020.C10F_4, SCOPUS ID：85098093049 - Ultra-fast waveform measurement in single-shot using optical frequency comb analyzer
Hiroaki Tada; Leona Yuda; Nasrin Sultana; Hayate Imai; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 巻：Part F181-CLEO-AT 2020, 2020年
© OSA 2020 © 2020 The Author(s). The 2.7ps time resolution of single shot waveform measurement was experimentally performed by measuring on frequency domain using improved optical frequency comb analyzer based on dual-heterodyne mixing in time-division multiplexing.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/CLEO_AT.2020.JW2B.28
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DOI ID：10.1364/CLEO_AT.2020.JW2B.28, ISSN：1092-8081, SCOPUS ID：85095129429 - Scan-less dispersion spectroscopy with single-shot dual-heterodyne mixing and optical frequency comb
Sultana Nasrin; Hiroaki Tada; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 巻：Part F181-CLEO-AT 2020, 2020年
© 2020 The Author(s). High-speed dispersion spectroscopy has been developed with wide dispersion range, while avoiding an increase in imprecision, by 1.4- and 50 GHz frequency intervals parallel processing of single-shot dual-heterodyne mixing combined with an optical frequency comb.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/CLEO_AT.2020.JTh2C.10
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DOI ID：10.1364/CLEO_AT.2020.JTh2C.10, ISSN：1092-8081, SCOPUS ID：85095118308 - Dispersion spectroscopy with optical frequency comb-based single-shot dual-heterodyne mixing
Sultana Nasrin; Hiroaki Tada; Leona Yuda; Tatsutoshi Shioda
Applied Optics, 巻：58, 号：33, 開始ページ：9044, 終了ページ：9050, 2019年11月
© 2019 Optical Society of America. We present a novel approach to high-speed dispersion spectroscopy that realizes a wide dynamic range, by simultaneous and parallel phase measurement using scanless dual-heterodyne mixing of 50 and 1.4 GHz frequency intervals. This system can realize parallel measurements of the relative phases between adjacent frequencies by introducing an optical frequency comb and intensity modulator to generate adjacent frequency and arrayed waveguide grating to separate the sidebands. The experimental results using single-mode fibers, whose lengths range from 0 to 92 km, indicated a 26 nm dispersion spectrum, 1785 ps/nm measurement range, and 0.27 ps/nm measurement uncertainty in 1 ms.
研究論文（学術雑誌）
DOI：https://doi.org/10.1364/AO.58.009044
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DOI ID：10.1364/AO.58.009044, ISSN：1559-128X, eISSN：2155-3165, PubMed ID：31873579, SCOPUS ID：85075268809 - High-speed and single-shot waveform measurement for elucidation of irreversible chemical reaction dynamics
Hiroaki Tada; Leona Yuda; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 巻：Part F149-LSC 2019, 2019年
© 2019 The Author(s). The single-shot optical waveform measurement was measured on a frequency axis by the improved frequency comb analyzer using dual-heterodyne mixing in time-division multiplexing. The 2.7 ps time resolution of the single-shot measurement was performed.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/LSC.2019.LTh4B.4
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85084486904&origin=inward
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DOI ID：10.1364/LSC.2019.LTh4B.4, SCOPUS ID：85084486904 - High-speed 2D single-shot surface profilometry for industrial inspection under vibrational environment
Toshiki Awane; Tuan Quoc Banh; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 巻：Part F149-LSC 2019, 2019年
© 2019 The Author(s). The image of 2D single-shot interferometry based high-speed camera at a shutter speed of ~1μs, which crosses over the limit of conventional OCTs, was experimentally observed. The optical shapes were captured even under vibrational environment.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/LSC.2019.LM4B.6
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DOI ID：10.1364/LSC.2019.LM4B.6, SCOPUS ID：85084423852 - Dispersion spectrum measurement using scan-less dual-heterodyne mixing
Sultana Nasrin; Hiroaki Tada; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 巻：Part F139-ASSL 2019, 2019年
© 2019 The Author (s). Dispersion spectroscopy with high-speed, high-resolution and wide dynamic range by parallel and simultaneous phase measurement using scan-less dual-heterodyne mixing of 1.4- and 50 GHz adjacent frequency intervals of optical frequency comb.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/ASSL.2019.JTh3A.49
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85084530076&origin=inward
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DOI ID：10.1364/ASSL.2019.JTh3A.49, SCOPUS ID：85084530076 - High-speed optical frequency comb analyzer with single-detection technique for ultrafast waveform measurement
Leona Yuda; Takashi Hasegawa; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 巻：Part F113-CLEOPR 2018, 2018年
© OSA 2018 Ultrafast-phase spectrum analyzer for 25 GHz × 45 lines frequency comb has been developed with novel optical delay-circuit system and single detector. It can be applied to single-shot optical waveform measurement system with femto-second time-resolution.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/cleopr.2018.tu2f.5
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DOI ID：10.1364/cleopr.2018.tu2f.5, SCOPUS ID：85059391531 - Improvement of frequency accuracy of spatially-resolved spectroscopy / tomographic spectroscopy
Shohei Gunji; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 巻：Part F113-CLEOPR 2018, 2018年
© OSA 2018 Novel calibration method for tomographic spectroscopy with high-depth resolution is proposed. Measured depth resolution has been achieved to 1.1 µm, and the frequency accuracy was improved from 10.6 THz to 0.8 THz by calibration.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/cleopr.2018.tu2f.4
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85059413090&origin=inward
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DOI ID：10.1364/cleopr.2018.tu2f.4, SCOPUS ID：85059413090 - Frequency domain 2D incoherent comb interferometry for single-shot tomographic imaging
Futoshi Kokubun; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 巻：Part F113-CLEOPR 2018, 2018年
© OSA 2018 Frequency-domain VIPA installed comb interferometry has been developed for 2D single-shot tomography. An etalon co-installed with VIPA to generate 2.2 THz incoherent comb brings multiple and periodic higher-order interference fringes, which expands the measurement range.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/cleopr.2018.w4f.6
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DOI ID：10.1364/cleopr.2018.w4f.6, SCOPUS ID：85059393159 - High-resolution spectroscopy using a frequency-variable comb light source
Hiroaki Sugimoto; Mitsutaka Ito; Motohiro Koriba; Satoshi Seki; Tatsutoshi Shioda; Yosuke Tanaka; Ken Kashiwagi; Takashi Kurokawa
2016 IEEE Photonics Conference, IPC 2016, 開始ページ：152, 終了ページ：153, 2017年01月, ［査読有り］
© 2016 IEEE. We propose a high-resolution spectroscopy using 12.5-GHz-spaced laser frequency comb whose individual lines are shifted continuously using a single-sideband modulator. It was applied to measure the absorption spectrum of H13C14N gas in 1.55 μm wavelength range in MHz resolution.
IEEE, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/IPCon.2016.7831021
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DOI ID：10.1109/IPCon.2016.7831021, ISSN：2374-0140, SCOPUS ID：85014248152, Web of Science ID：WOS:000406880100080 - Time range extension of ultrafast waveform measurement by using optical frequency comb synthesizer/analyzer
Takashi Hasegawa; Takayuki Miyamoto; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 巻：Part F43-CLEO_AT 2017, 開始ページ：1, 終了ページ：2, 2017年
© 2017 OSA. Single-shot ultrafast waveform measurement system with time-resolution in femtosecond and time-range of 40 pico-second has been developed using 200 GHz optical frequency comb synthesizer and analyzer by means of the proposed time window extension technology.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/CLEO_AT.2017.JTh2A.132
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DOI ID：10.1364/CLEO_AT.2017.JTh2A.132, SCOPUS ID：85020434605 - Optical dispersion spectroscopy using optical frequency comb applied to dual-heterodyne mixing
Kaishu Kasuga; Takayuki Miyamoto; Tatsutoshi Shioda
Proceedings of SPIE - The International Society for Optical Engineering, 巻：9754, 2016年
© 2016 SPIE. The optical dispersion can be obtained from the adjacent relative phase between neighbor peaks in the optical frequency comb. Thus, the dispersion measurement becomes possible by measuring the relative phase spectrum. Our group has experimentally confirmed the operation principle by parallel capturing of the dispersion spectrum using an arrayed waveguide grating. We have proposed a dual-heterodyne mixing that obtained relative phases (ΔΦ) by fitting data of beat intensity versus optical path length difference. The path difference was applied by a delay line. In this study, we removed the delay line to realize a fast measurement by measuring simultaneous three relative phases with path length differences corresponding to π/2 or π, with which we have measured the dispersion in millisecond speed (250 sec. in previous). In general, it is effective to measured chromatic dispersion using high-speed signal transmission in the fundamental scientific research, such as the analysis of material properties and telecommunications. It is, however, that limit of cutoff frequency using measurement is the restriction on increasing of the speed. Our proposed method to observe it on a frequency domain is effective for the high-speed signal processing.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1117/12.2212365
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DOI ID：10.1117/12.2212365, ISSN：0277-786X, eISSN：1996-756X, SCOPUS ID：84987643679 - A pseudo optical frequency comb interferometry by an optical resonator and a high-speed swept-source for 2D single-shot tomography and profilometry
Q. T. Banh; T. Shioda
Proceedings of SPIE - The International Society for Optical Engineering, 巻：9754, 2016年
© 2016 SPIE. Pseudo optical frequency comb using a high-speed frequency laser scanner and an optical resonator is generated as a virtual broadband lightsource for the time-domain 2D single-shot tomography and profilometry. High-speed laser scanner (40 kHz) is realized using a broadband semiconductor optical amplifier (SOA) whose individual wavelengths are consequently picked up by a conventional grating setup and a high speed polygon mirror. The performance of the pseudo frequency comb is confirmed by a measurement of a reference step-height sample with an optical zooming operation.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1117/12.2211995
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DOI ID：10.1117/12.2211995, ISSN：0277-786X, eISSN：1996-756X, SCOPUS ID：84987605258 - Spatially resolved spectroscopy using swept-source optical interferometry
Ryoma Onita; Tatsutoshi Shioda
Proceedings of SPIE - The International Society for Optical Engineering, 巻：9754, 2016年
© 2016 SPIE. We describe principle of spatially-resolved spectroscopy using swept source optical interferometry and demonstrate it using a multi-layered polypropylene and glass plates piled sample. The advantages of this technique compared to conventional spectroscopy technique are realizing spatially-resolved spectroscopy as transmittance spectra of each layer and obtaining tomographic image of the sample simultaneously. Moreover, potential for spectroscopy is the method we propose can calculate absorption coefficient of each mediums. In this demonstration, we could 1D tomographic image of multi-layered sample and characterize PP layer and glass layer by comparing transmittance spectra in near infrared region.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1117/12.2212228
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DOI ID：10.1117/12.2212228, ISSN：0277-786X, eISSN：1996-756X, SCOPUS ID：84987618893 - Frequency-domain single-shot optical frequency comb tomography using VIPA
Takumi Miyaoka; Tatsutoshi Shioda
Proceedings of SPIE - The International Society for Optical Engineering, 巻：9754, 2016年
© 2016 SPIE. Novel two-dimensional single-shot imaging optical system based on Frequency-domain interferometry using a virtually imaged phased array is proposed. The VIPA simultaneously outputs incoherent optical frequency combs (OFCs) whose teeth interval are scanned as a function of its output angle. Teeth intervals of the OFCs only in a reference are spatially swept by using of a VIPA whose advantage compared to an optical resonator. Thus, the single-shot imaging system can be realized with the FSR scanned frequency-domain OFC interference monitored by CCD. This system enable high speed 2-dimensional tomographic image without mechanical moving part. And the axial measurement range is not limited by using multi-order interference that is generated by OFCs interferometry. We will present the operation principle with its confirmed results in terms of both simulation and experiment.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1117/12.2212093
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DOI ID：10.1117/12.2212093, ISSN：0277-786X, eISSN：1996-756X, SCOPUS ID：84987653325 - Two-dimensional high-speed and long-range tomography and profilometry using liquid-crystal Fabry-Perot resonator
Tuan Quoc Banh; Kohei Suzuki; Munehiro Kimura; Tatsutoshi Shioda
Applied Optics, 巻：54, 号：4, 開始ページ：912, 終了ページ：918, 2015年
© 2015 Optical Society of America. A two-dimensional high-speed, long-range tomography and profilometry based on a low-coherence optical interferometry has been developed. A liquid-crystal Fabry-Perot resonator is fabricated to be a lowcoherence optical frequency comb generator for expanding the measurement depth of the tomography and profilometry. The line-shape interference fringes with the individual fringe orders are obtained by a CCD camera in real time. The relative optical length, corresponding to the sample depth information, can be derived from the positions of the interference fringes on the CCD camera and their corresponding fringe orders. The fringe orders can be rapidly calculated using the effectiveness of the changeable extraordinary refractive index of the liquid-crystal material of the resonator. The finesse of the liquid-crystal resonator is approximate 9, giving an expansion of the measurement range of up to 9-fold (∼8 mmdepth)with a resolution of profilometry and tomography of 3.7 μmand11μm, respectively.
研究論文（学術雑誌）
DOI：https://doi.org/10.1364/AO.54.000912
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DOI ID：10.1364/AO.54.000912, ISSN：1559-128X, eISSN：2155-3165, SCOPUS ID：84942372468 - Single-shot, long-range, and zoomable optical tomography and profilometry using a diffraction grating and a CCD camera
Q. T. Banh; T. Kosakai; T. Shioda
Proceedings of SPIE - The International Society for Optical Engineering, 巻：9655, 2015年
© 2015 Copyright SPIE. We have developed a novel single-shot optical tomography and profilometry that is able to measure the tomograms and surface profiles of a sample in realtime with long measurable range. The system comprises of an optical frequency comb interferometry and a diffraction grating. The grating plays as a spatial phase modulator (SPM), so that the realtime interference images can be achieved by a CCD camera. Owing to the diffraction lights by the SPM, the axial zooming operation of the proposed system can be realized. The zooming range of the proposed system depends on how many diffraction orders are generated by the SPM. Measurements of a reference Gauge-block step-height sample at different diffraction orders are performed to evaluate the proposed system.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1117/12.2184422
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DOI ID：10.1117/12.2184422, ISSN：0277-786X, eISSN：1996-756X, SCOPUS ID：84939214012 - Novel two-dimensional single-shot optical imaging system by VIPA-comb interferometry
Takumi Miyaoka; Tatsutoshi Shioda
Proceedings of SPIE - The International Society for Optical Engineering, 巻：9655, 2015年
© 2015 Copyright SPIE. We propose a novel system for a two-dimensional (2-D) single-shot tomography and profilometry that can be realized by installing a Virtually Imaged Phased Array (VIPA) into a 2-D interferometer with a CCD. The VIPA simultaneously outputs incoherent optical frequency combs (OFC) whose teeth interval, such as free-spectral range (FSR), are scanned as a function of its output angle when the low-coherent light source is incident into the VIPA. Thus, the single-shot imaging can be realized with the FSR scanned Fourier-domain OFC interference monitored by the CCD. In other words, the fast imaging without mechanical moving part can be operated by the proposed OFC interferometry. And VIPA can use all of incident light. So this system enables to realize a high energy efficient interference measurement. FSR of the output light of the VIPA is nonlinear with respect to the sweep direction. So we simulated the characteristics of the VIPA. As a result, we knew linearity optimal output angle depend on reflective index of the VIPA. And the VIPA can change the measurement range on the CCD by the number. In other word, the VIPA can zoom in and out no mechanical part. We will present the operation principle with its confirmed results in terms of both simulation and experiment.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1117/12.2185168
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DOI ID：10.1117/12.2185168, ISSN：0277-786X, eISSN：1996-756X, SCOPUS ID：84939168602 - Single-shot optical frequency comb imaging using VIPA
Takumi Miyaoka; Tatsutoshi Shioda
Optical Sensors, Sensors 2015, 開始ページ：316p, 2015年
Virtually imaged phased array (VIPA) makes a traditional tomography upgraded to single-shot and wide range 2-dimensional imaging tomography. We propose a novel Fourierdomain comb interferometry with a combination of the VIPA and CCD. © 2015 OSA.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/SENSORS.2015.SeS1B.6
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DOI ID：10.1364/SENSORS.2015.SeS1B.6, SCOPUS ID：84940395892 - Control the optical magnification of a zooming tomography and profilometry with a spatial phase modulator installed interferometer
Tuan Banh Quoc; Tatsutoshi Shioda
Optical Sensors, Sensors 2015, 開始ページ：316p, 2015年
Optical magnification of the high-speed 2D imaging is proposed as a zooming tomography using optical grating and camera installed interferometer. The dynamic range can be optically changed by choosing the diffraction orders of the grating. © 2015 OSA.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/SENSORS.2015.SeT4C.5
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84940398527&origin=inward
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DOI ID：10.1364/SENSORS.2015.SeT4C.5, SCOPUS ID：84940398527 - Frequency-variable comb light source using an optical frequency shifter
Satoshi Seki; Tatsutoshi Shioda; Ken Kashiwagi; Yosuke Tanaka; Takashi Kurokawa
Frontiers in Optics, FiO 2014, 2014年10月
© OSA 2014. We propose a frequency variable multi-gigahertz-comb light source whose modes are swept over its mode-spacing frequency. We successfully demonstrated a fine sweep of the laser frequency comb ranging from 1520 to 1565 nm.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/fio.2014.fm3c.2
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DOI ID：10.1364/fio.2014.fm3c.2, SCOPUS ID：85088064626 - 2D single-shot profilometry for scattered media using Supercontinuum source interferometry in visible region
Tuan Banh Quoc; Tuan Truong Cong; Heui Hyeon Kim; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 2014年07月
© OSA 2016. Supercontinuum light and visible camera are employed for improving resolution of our 2D single-shot, long-range interferometry. A 3D plot of a profile surface of a scattered sample is effectively demonstrated.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/APOS.2016.Th1A.5
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DOI ID：10.1364/APOS.2016.Th1A.5, SCOPUS ID：85019522126 - Long-range single-shot 2-dimensional profilometry using multi-order comb interferometry
Hikaru Ariya; Banh Quoc Tuan; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 2014年07月
© OSA 2016. Multiple interference orders of optical frequency comb interferometry expands a measurement range of profilometry and tomography. The order was identified by using two lowcoherent combs with different teeth intervals generated from a supercontinuum light source.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/APOS.2016.Th1A.6
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DOI ID：10.1364/APOS.2016.Th1A.6, SCOPUS ID：85019530236 - Optical frequency comb interferometry for single-shot 2-dimensional imaging
Tatsutoshi Shioda; Hikaru Ariya
Optics InfoBase Conference Papers, 2014年07月
© OSA 2016. Multiple interference orders of an optical frequency comb interferometry extend a measurement range of a single-shot 2-dimensional tomography based on a technology of two combs simultaneous generation with different repetition rate by a chromatic resonator.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/iprsn.2016.jtu4a.17
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DOI ID：10.1364/iprsn.2016.jtu4a.17, SCOPUS ID：85016990076 - Magneto-optical diffraction by periodic lateral arrays composed of GMR structures of Pt/Co free layers having perpendicular magnetization
Kakeru Wada; Tsukasa Kobayashi; Akira Emoto; Ken Ichi Aoshima; Kenji Machida; Kiyoshi Kuga; Tatsutoshi Shioda; Hiroshi Ono; Hiroshi Kikuchi; Naoki Shimidzu; Takayuki Ishibashi
Optics Communications, 巻：323, 開始ページ：123, 終了ページ：127, 2014年07月
A first-order beam diffracted by periodic arrays of GMR structures consisting of Pt/Co free layers having perpendicular magnetization without a top electrode is investigated. Linear and two-dimensional arrays of various shapes having sizes of 10-50 μm and periods of 20-100 μm embedded in SiO 2 are fabricated. The angles of the plane of polarization for first or (1,0) diffraction spots at a wavelength of 633 nm are measured to be approximately 0.5 for all samples. The polarization angles for one- and two-dimensional arrays of magnetic patterns are studied theoretically by assuming that the structures have sinusoidal magnetic distributions. They are found to depend on the Kerr rotation angle of the Pt/Co multilayer and on the difference in reflectance between the Pt/Co and SiO2, but they are independent of the periodicities, sizes, and shapes of the patterns. On the other hand, the diffraction efficiencies due to the magneto-optical effect depend on the reflectance and Kerr rotation angles of the magnetic materials. The diffraction efficiency of the component arising from the magneto-optical effect is discussed. © 2014 Elsevier B.V.
研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.optcom.2014.02.064
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DOI ID：10.1016/j.optcom.2014.02.064, ISSN：0030-4018, SCOPUS ID：84897857352 - Dispersion measurement and compensation using optical frequency comb
Mitsutaka Ito; Takayuki Miyamoto; Masaichi Nakamura; Toshiaki Yamazaki; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 巻：2014-January, 2014年
A dispersion spectrum in a 3.2 Tbit/s waveform generation was controlled /compensated by a 200 GHz optical frequency comb synthesizer and optical frequency comb analyzer simultaneously. © 2014 OSA.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/cleo_at.2014.jth2a.4
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DOI ID：10.1364/cleo_at.2014.jth2a.4, eISSN：2162-2701, SCOPUS ID：84905455838 - Application of dual-heterodyne mixing to optical phase-shift keying
Toshiaki Yamazaki; Tatsutoshi Shioda
Japanese Journal of Applied Physics, 巻：53, 号：1, 2014年01月, ［査読有り］
Dual-heterodyne mixing has been developed to detect high-speed optical signal waveforms and measure not only the amplitude spectrum but also the phase spectrum. In the present study, this method was applied to a simple experiment that demodulated intensity-modulated terabit signals, and it successfully demodulated an 80 ps non monotonic optical pulse train of 12.5 Gbps 8 bit phase-modulated signals as arbitrary waveforms with dual-heterodyne mixing. These results will be the foundation for phase-shift-keying technology that increases future communication capacity.© 2014 The Japan Society of Applied Physics.
IOP PUBLISHING LTD, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.7567/JJAP.53.012501
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DOI ID：10.7567/JJAP.53.012501, ISSN：0021-4922, eISSN：1347-4065, SCOPUS ID：84892401428, Web of Science ID：WOS:000331412300025 - Development of an incoherent optical frequency comb interferometer for long-range and scanless profilometry and tomography
Tuan Quoc Banh; Kohei Suzuki; Tatsutoshi Shioda
Optics Communications, 巻：296, 開始ページ：1, 終了ページ：8, 2013年06月
An optical resonator was installed as an incoherent frequency comb generator into a two-dimensional single-shot profilometry and tomography system to increase the measurement range up to 30 times compared with a conventional white-light interferometer. The dynamic range of the sample set position was experimentally confirmed to be ∼28 mm, equivalent to the coherency of the resonator. Scanless measurement can be achieved through high-order comb interference. In this study, we demonstrated tomography with a resolution of ∼11 μm and effective high-order interference fringe discrimination. © 2013 Elsevier B.V. All rights reserved.
研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.optcom.2013.01.027
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DOI ID：10.1016/j.optcom.2013.01.027, ISSN：0030-4018, SCOPUS ID：84875886867 - Improvement of the 2D single-shot tomography and profilometry for a scattered media
Tuan Banh Quoc; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 2013年
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/jsap.2013.19a_d5_5
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DOI ID：10.1364/jsap.2013.19a_d5_5, eISSN：2162-2701, SCOPUS ID：85088345213 - Polarization state of scattered light in apertureless reflection-mode scanning near-field optical microscopy
Yongfu Cai; Mitsuharu Aoyagi; Akira Emoto; Tatsutoshi Shioda; Takayuki Ishibashi
Journal of Magnetics, 巻：18, 号：3, 開始ページ：317, 終了ページ：320, 2013年
We studied the polarization state in an apertureless scanning near-field microscopy (a-SNOM) operating in reflection mode by using three-dimensional Finite-difference Time-domain (FDTD) method. As a result, the electric field around tip apex in the near-field region enhanced four times stronger than the incident light for ppolarization when the tip-sample separation was 10 nm. We find that the p- and s-polarization state is maintained for the scattered light when the probe is perpendicular to the sample. When the probe is not perpendicular to the sample, the polarization state of scattered light will rotate an angle that equals to the inclination angle of probe with p-polarization illumination. On the other hand, the polarization state will not rotate with s-polarization illumination. © The Korean Magnetics Society. All rights reserved.
研究論文（学術雑誌）
DOI：https://doi.org/10.4283/JMAG.2013.18.3.317
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DOI ID：10.4283/JMAG.2013.18.3.317, ISSN：1226-1750, SCOPUS ID：84884804066 - Application of optical frequency comb synthesizer/analyzer to Tbit multilevel phase modulation
Toshiaki Yamazaki; Tatsutoshi Shioda
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, 2013年
Novel optical system for arbitrary waveform synthesizing and analyzing in terabit range has been proposed based on a 200 GHz optical frequency comb. As a demonstration 16-Tbit/s 80-bit PSK packet was experimentally synthesized and analyzed. © 2013 IEEE.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEOPR.2013.6600042
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DOI ID：10.1109/CLEOPR.2013.6600042, SCOPUS ID：84885464239 - Spatially-resolved spectroscopy for simultaneous distinguishment of both structures and materials
Tatsutoshi Shioda; Tuan Banh Quoc
Optics InfoBase Conference Papers, 2013年
A spatially-resolved spectroscopy is developed based on a time-domain tomography to measure the reflectance and transmittance of materials. Power transmittance of a known filter sample is measured as a demonstration of the system. © OSA 2013.
研究論文（国際会議プロシーディングス）
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eISSN：2162-2701, SCOPUS ID：84898060636 - Multi-gigahertz frequency comb-based interferometry using frequency-variable supercontinuum generated by optical pulse synthesizer
Samuel Choi; Ken Kasiwagi; Yosuke Kasuya; Shuto Kojima; Tatsutoshi Shioda; Takashi Kurokawa
Optics Express, 巻：20, 号：25, 開始ページ：27820, 終了ページ：27829, 2012年12月
A multi-gigahertz frequency comb (MGFC)-based interferometer was developed for profilometry and tomography using a frequency variable supercontinuum (SC). The comparatively flattened and broadened SC light source with variable multi-gigahertz interval frequency was developed using an optical pulse synthesizer and highly nonlinear dispersion flattened fiber. The generated SC provided a stable interference output with a full width half maximum of 19 μ m during interval frequency sweeping of over 400 MHz. We experimentally confirmed that the interference signal exhibited an envelope-only waveform without fringes, which enabled the drastic reduction of the sampling points resulting in high speed measurement. A full-field 3-D image with 320 × 256 × 300 pixels was acquired with a measurement time of only 10 seconds. It was demonstrated that the MGFC-based interferometer with the novel SC light source has the potential for application in a high speed full-field 3-D metrology. © 2012 Optical Society of America.
研究論文（学術雑誌）
DOI：https://doi.org/10.1364/OE.20.027820
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DOI ID：10.1364/OE.20.027820, eISSN：1094-4087, PubMed ID：23262727, SCOPUS ID：84870584945 - Three-wavelength parallel optical fiber dispersion measurement using dual-heterodyne mixing
Tatsutoshi Shioda; Naoya Shimizu; Masaichi Nakamura
Applied Optics, 巻：51, 号：27, 開始ページ：6586, 終了ページ：6593, 2012年09月
We propose a novel optical dispersion measurement system using dual-heterodyne mixing to measure the relative phase. The system can realize parallel measurement of the relative phases between adjacent frequencies by introducing optical modulators to generate optical sidebands from a laser light source and an arrayed waveguide grating to separate the sidebands. To realize a wide dispersion range, different frequency intervals for the adjacent frequencies were combined in the system. One is the three-frequency optical dispersion measurement system (three-frequency measurement), which has been developed to measure the relative phase between adjacent peaks of an optical frequency spectrum with intervals of 25 GHz generated without any frequency scanning. The other is the four-frequency optical dispersion measurement system (four-frequency measurement) with intervals of 2 GHz generated from the threefrequency sets to expand the measurement range. The experimental results using single-mode optical fibers of different lengths from 0 to 90 km indicated the dispersion slope to be 16.8 ps/nm/km with a measurement range of 2500 ps/nm and an uncertainty of less than 1 ps/nm. The proposed system provides advantages to enable parallel measurement on a frequency axis without a high-speed (GHz) photodetector, even though GHz spacing on the optical scale is used, thus reflecting the dual-heterodyne mixing. © 2012 Optical Society of America.
研究論文（学術雑誌）
DOI：https://doi.org/10.1364/AO.51.006586
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DOI ID：10.1364/AO.51.006586, ISSN：1559-128X, eISSN：1539-4522, SCOPUS ID：84866640666 - Ultrafast optical frequency comb synthesizer and analyzer
Tatsutoshi Shioda; Toshiaki Yamazaki
Optics Letters, 巻：37, 号：17, 開始ページ：3642, 終了ページ：3644, 2012年09月
We propose an ultrafast optical arbitrary waveform synthesizing/analyzing technique demonstrated with 2 Tbit/s waveforms. An ultrafast waveform was generated by manipulating the amplitude and phase of a 400 GHz optical frequency comb using a newly developed colorless optical synthesizer. The 400 GHz optical frequency comb was generated from a 25 GHz optical frequency comb using a colorless arrayed waveguide grating. This waveform was then analyzed on the frequency axis using a custom heterodyne-detection technique based on the dual-heterodyne mixing method. The phase and amplitude spectra can be observed in parallel using another optical frequency comb as a reference combined with an arrayed waveguide grating. This optical system, named the ultrafast optical frequency comb synthesizer and analyzer, can synthesize and analyze an arbitrary waveform in the THz frequency region. © 2012 Optical Society of America.
研究論文（学術雑誌）
DOI：https://doi.org/10.1364/OL.37.003642
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DOI ID：10.1364/OL.37.003642, ISSN：0146-9592, eISSN：1539-4794, SCOPUS ID：84865794830 - Two-dimensional single-shot tomography using a virtually imaged phased array and a spatial phase modulator
Tatsutoshi Shioda; Takashi Morisaki; Tuan Quoc Banh; Kohei Suzuki
Applied Optics, 巻：51, 号：21, 開始ページ：5224, 終了ページ：5230, 2012年07月
A virtually imaged phased array (VIPA) installed optical interferometer has been expanded to the two-dimensional (2D) tomography from the previous one-dimensional single-shot imaging technique with keeping the resolution and the measurement range. A single-shot measurement has been realized by a spatial phase modulator installed in the optical interferometer and tracing the delay time to pixel numbers on a 2D charge-coupled device (CCD) image sensor. The flexibility of the sample position was experimentally confirmed to be >25 mm, in relation to the VIPA coherency, for which the number of the interference order was confirmed to be 35. As a demonstration, a surface profile of stacked gauge blocks was observed. The repeatability of the surface position was 5 μm for the surface profilometry. In addition, a multilayer structure was observed using a glass plate. The experimental resolution was 53 μm when the amplified spontaneous emission light generated by the optical fiber amplifier was used for the light source. The single-shot measurement was confirmed by the 2D-CCD at a frame rate of 30 frames per second (FPS), and it provided evidence that the 2D scanless profilometry was successfully achieved using the VIPA optical device. © 2012 Optical Society of America.
研究論文（学術雑誌）
DOI：https://doi.org/10.1364/AO.51.005224
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DOI ID：10.1364/AO.51.005224, ISSN：1559-128X, eISSN：1539-4522, SCOPUS ID：84864194032 - Spectral waveform measurement of 2 THz optical frequency comb by dual-heterodyne mixing
Toshiaki Yamazaki; Mitsuru Kuzuwata; Tatsutoshi Shioda
Journal of the Optical Society of America B: Optical Physics, 巻：29, 号：7, 開始ページ：1707, 終了ページ：1711, 2012年07月
A technique for measuring the relative phase between optical longitudinal modes in an optical frequency comb (OFC) has been proposed, and applied to the characterization of the OFC. The measurement frequency range was expanded to 2 THz using the OFC of a line spacing of 10 GHz. Furthermore, an algorithm for data analysis was proposed by calculating Fourier transformation of the fragmentized waveform of the data measured by the dualheterodyne mixing method. As a result, a pulse width of 2.1 ps was observed on a time scale of 100 ps with a resolution of 500 fs, which is inversely proportional to the measured frequency band in general (2 THz in this study). These results were also compared with those obtained from an optical autocorrelator. The measured electric field spectra provide a lot of information, involving a frequency-resolved optical gating (FROG) trace and a phase variation profile plotted against time. Amplitude and phase spectral evolutions were reconstructed directly from the electric field spectra and referred to as a dual-heterodyne mixing trace. In conclusion, it was confirmed that the proposed technique is effective in reading out detailed information from the ultrafast waveform measurement. © 2012 Optical Society of America.
研究論文（学術雑誌）
DOI：https://doi.org/10.1364/JOSAB.29.001707
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DOI ID：10.1364/JOSAB.29.001707, ISSN：0740-3224, SCOPUS ID：84863827992 - Proposal of a three-dimensional and long range tomography using optical frequency comb interferometry
Tuan Quoc Banh; Tatsutoshi Shioda; Kohei Suzuki; Munehiro Kimura
Applied Industrial Optics: Spectroscopy, Imaging and Metrology, AIO 2012, 2012年
Coherence property of a broadband, near-infrared light is enhanced to construct a 3-dimensional tomography with the consideration of the measurement depth expansion, themeasurement time reduction, and the sample scattering problem. © 2012 OSA.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/aio.2012.ath1a.1
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DOI ID：10.1364/aio.2012.ath1a.1, SCOPUS ID：84890515448 - Development of a tunable optical frequency comb
T. Quoc Banh; K. Suzuki; M. Kimura; T. Shioda
Technical Digest - 2012 17th Opto-Electronics and Communications Conference, OECC 2012, 開始ページ：574, 終了ページ：575, 2012年
A liquid-crystal doped Fabry-Perot cavity as frequency-combs generator is presented. FSR of the cavity can be detuned by controlling extraordinary refractive-index of liquid-crystal. Generated frequency-combs are applied for expanding measurement depth of a single-shot tomography. © 2012 IEEE.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/OECC.2012.6276578
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DOI ID：10.1109/OECC.2012.6276578, SCOPUS ID：84867591223 - Optical dispersion spectroscopy using optical frequency comb
Masaichi Nakamura; Naoya Shimizu; Toshiaki Yamazaki; Hiroshi Ono; Tatsutoshi Shioda
2012 IEEE Photonics Conference, IPC 2012, 開始ページ：737, 終了ページ：738, 2012年
Novel optical dispersion spectroscopy has been developed with a dynamic range of 2500 ps/nm and a resolution of < 1 ps/nm. It was realized using dual-heterodyne mixing with 25 GHz- and 2 GHz-optical frequency combs. © 2012 IEEE.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/IPCon.2012.6358833
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DOI ID：10.1109/IPCon.2012.6358833, SCOPUS ID：84871812786 - Novel tomography of simultaneous imaging and material characterization by spatially-resolved spectroscopy
Masaya Sakatsume; Yukihiro Mikawa; Tuan Quoc Banh; Tatsutoshi Shioda
2012 IEEE Photonics Conference, IPC 2012, 開始ページ：593, 終了ページ：594, 2012年
Novel tomography was developed to observe both tomographic imaging and tomographic spectroscopic simultaneously. This method can obtain the electric field spectra of each slice in sample with optical parameters, as complex refractive index, refractivity, transmittance,... © 2012 IEEE.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/IPCon.2012.6358760
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DOI ID：10.1109/IPCon.2012.6358760, SCOPUS ID：84871784445 - Novel terabit optical waveform synthesizer and digital holographic analyzer based on 400 GHz optical frequency comb
Tatsutoshi Shioda; Toshiaki Yamazaki
2012 IEEE Photonics Conference, IPC 2012, 開始ページ：493, 終了ページ：494, 2012年
A novel arbitral waveform synthesizing and analyzing system in terabit range has been proposed and demonstrated with the 400 GHz high-speed optical frequency comb. 2-Tbit/s 4-bit packets were experimentally synthesized and analyzed for the demonstration. © 2012 IEEE.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/IPCon.2012.6358708
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DOI ID：10.1109/IPCon.2012.6358708, SCOPUS ID：84871769891 - High-resolution spectroscopy using interleaved 100 GHz optical frequency comb scanned by phase modulator
Tatsutoshi Shioda; Kenichiro Fujii; Ken Kashiwagi; Takashi Kurokawa
Optics Communications, 巻：284, 号：21, 開始ページ：5180, 終了ページ：5184, 2011年10月, ［査読有り］
A high-resolution spectroscopy technique is proposed with an optical phase modulator combined with an interleaved optical frequency comb. The optical phase modulator and a frequency-locked laser light guarantee a spectral resolution less than 1 MHz on an absolute frequency axis. A wide measurement frequency range was realized using a 25 GHz optical frequency comb lying over a 4 THz frequency region. An extraction of single tooth intensity from the comb was realized by a heterodyne technique with a frequency-tunable laser used as a local oscillator. Also, the 25 GHz optical frequency comb was interleaved to generate four 100-GHz combs for removing the crosstalk from the 25 GHz neighboring sidebands in the teeth. This proposed spectroscopy technique was experimentally demonstrated with a resonator of less than 1 MHz linewidth and a H13C14N gas cell. Thus, a measurement frequency range higher than 4 THz (1530 nm-1560 nm) was confirmed with an effective spectral resolution 100 kHz order. In addition, the characteristics of the proposed system were compared with those of the previous system with a single-sideband (SSB) optical modulator. © 2011 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.optcom.2011.07.006
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DOI ID：10.1016/j.optcom.2011.07.006, ISSN：0030-4018, eISSN：1873-0310, SCOPUS ID：80052816683, Web of Science ID：WOS:000295608600027 - Vector gratings fabricated by polarizer rotation exposure to hydrogen-bonded liquid crystalline polymers
Akira Emoto; Takumi Wada; Tatsutoshi Shioda; Tomoyuki Sasaki; Sayaka Manabe; Nobuhiro Kawatsuki; Hiroshi Ono
Japanese Journal of Applied Physics, 巻：50, 号：3, 2011年03月
We present a simple yet efficient, competitive, and practical fabrication method, called "polarizer rotation exposure", for preparing vector gratings with a large area and a high diffraction efficiency. The polarization states of ultraviolet light were modulated by rotating the polarizer, and the resultant ultraviolet light was line-focused onto hydrogen-bonded liquid crystalline polymer films set on a linear stage. Mesogenic molecules in the polymer films were reoriented according to the light electric vectors, and vector gratings in which the optical anisotropy is periodically modulated were fabricated by the polarizer rotation exposure method. © 2011 The Japan Society of Applied Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.50.032502
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DOI ID：10.1143/JJAP.50.032502, ISSN：0021-4922, eISSN：1347-4065, SCOPUS ID：79953081260 - Spectral waveform measurement of 500 GHz pulse by Dual Heterodyne Mixing Method
Mitsuru Kuzuwata; Toshiaki Yamazaki; Hiroshi Ono; Tatsutoshi Shioda
2011 Int. Quantum Electron. Conf., IQEC 2011 and Conf. Lasers and Electro-Optics, CLEO Pacific Rim 2011 Incorporating the Australasian Conf. Optics, Lasers and Spectroscopy and the Australian Conf., 開始ページ：2160, 終了ページ：2162, 2011年
A novel holographic analyzer to measure phase and amplitude spectra has been proposed named as Dual Heterodyne Mixing Method. As a demonstration, 500 GHz band optical frequency comb was measured successfully. © 2011 IEEE.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/IQEC-CLEO.2011.6193860
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DOI ID：10.1109/IQEC-CLEO.2011.6193860, eISSN：2162-2701, SCOPUS ID：84862069070 - 2Tbit/s digital holographic optical frequency comb synthesizer and analyzer
Toshiaki Yamazaki; Hiroshi Ono; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 開始ページ：1156, 終了ページ：1157, 2011年
Optical complex electric field spectra of a 400 GHz optical frequency comb were controlled by a colorless optical synthesizer. The synthesized 2 Tb/s signals were measured by a proposed digital holographic optical frequency comb analyzer. © 2011 AOS.
研究論文（国際会議プロシーディングス）
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eISSN：2162-2701, SCOPUS ID：84893577676 - 2THz optical waveform measurement by development of digital holographic synthesizer & analyzer of 400GHz optical frequency comb
Toshiaki Yamazaki; Hiroshi Ono; Tatsutoshi Shioda
2011 Conference on Lasers and Electro-Optics: Laser Science to Photonic Applications, CLEO 2011, 2011年
Optical complex electric field spectra of a 400 GHz optical frequency comb were controlled by a colorless optical synthesizer. The synthesized 2 THz high-speed optical waveform was measured by a proposed multi-heterodyne mixing method. © 2011 OSA.
研究論文（国際会議プロシーディングス）
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eISSN：2162-2701, SCOPUS ID：80052107723 - Range expansion of single-shot surface profilometry by installing optical resonator into interferometer
Kohei Suzuki; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 開始ページ：535, 終了ページ：537, 2011年
We have proposed to install an optical resonator into an optical interferometer for expanding measurement dynamic range of a single shot profilometry. 30 times range expansion was experimentally confirmed. © 2011 AOS.
研究論文（国際会議プロシーディングス）
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eISSN：2162-2701, SCOPUS ID：84893542632 - Spatially distinguished spectroscopy and tomography using time-domain interferometer
Masaya Sakatasume; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 開始ページ：530, 終了ページ：532, 2011年
Novel calibration method for spatially resolved spectroscopy is proposed through a tomographic image obtained from time-domain interferometer. The operation principle was experimentally confirmed by measuring the thickness and reflectance of an optical resonator. © 2011 AOS.
研究論文（国際会議プロシーディングス）
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eISSN：2162-2701, SCOPUS ID：84893558625 - Single-shot tomography by means of VIPA and spatial phase modulator installed optical interferometer
Tatsutoshi Shioda; Takashi Morisaki; Hiroshi Ono
Optics Communications, 巻：284, 号：1, 開始ページ：144, 終了ページ：147, 2011年01月, ［査読有り］
A VIPA (virtually imaged phased array) installed optical interferometer has been proposed for scanless tomography. Also, a spatial phase modulator and a line-image sensor were installed into the interferometer to realize single-shot measurement by displaying the delay time on a line-image sensor. The correlation peak function was observed on the line-sensor at same time. The envelope of the peak was given by the inverse Fourier transformation of the light source spectrum. The peak position on the image-sensor reflects the sample structure. Furthermore, the correlation peaks are appeared repeatedly along the delay time of the interferometer. The repeated correlation function raise an alignment flexibility of the sample set position, which has been limited in the traditional time-domain interferometry involving the delay time to be zero. The flexibility was experimentally confirmed at 25 mm related to the VIPA coherency. The resolution was experimentally 52.5 μm when the ASE (amplified spontaneous emission) light source of the optical fiber amplifier was used. The single-shot measurement was realized by a line-image sensor of the 30 frames per second. The repeatability of the interfered peak position was 5 μm by the tunable mirror position. The one-dimensional scanless measurement was demonstrated by use of 3-layer glass plates. © 2010 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.optcom.2010.09.028
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DOI ID：10.1016/j.optcom.2010.09.028, ISSN：0030-4018, SCOPUS ID：78649683674, Web of Science ID：WOS:000285893200023 - Chronological investigations of Raman-Nath diffraction grating inscribed by direct laser writing in photoreactive monomer base mixtures
Akira Emoto; Suzana Binti Baharim; Tomoyuki Sasaki; Tatsutoshi Shioda; Akifumi Ogiwara; Hiroshi Ono
Japanese Journal of Applied Physics, 巻：49, 号：12, 2010年12月
Phase-type diffraction gratings, inscribed using an ultraviolet laser beam, were grown in a thin film of a photoreactive monomer base mixture over a period of several hours. The photopolymerization of monomers and subsequent molecular migrations generated both surface relief gratings and inner refractive index modulation. The changes in the diffraction intensity over time revealed the pronounced behavior of grating formation, which can be explained using a time-dependent model based on the Raman-Nath diffraction theory. Homogeneous irradiation with ultraviolet light during the growth enabled us to fix the diffraction characteristics of the gratings at an arbitrary moment in time, allowing us to tailor the resultant diffraction gratings according to a desired specification. This sequential process can have practical applications. © 2010 The Japan Society of Applied Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.49.122502
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DOI ID：10.1143/JJAP.49.122502, ISSN：0021-4922, eISSN：1347-4065, SCOPUS ID：79551663439 - Proposal of dual-heterodyne-mixing method and application to high-speed waveform measurement using low-speed equipments
Tatsutoshi Shioda; Toshiaki Yamazaki
Optics Communications, 巻：283, 号：23, 開始ページ：4733, 終了ページ：4740, 2010年12月, ［査読有り］
A novel method to measure a relative phase between frequency-different optical wavelengths has been proposed and named as Dual-heterodyne-mixing method. The operation principle of the method is represented, where the relative phase is simply described as dc voltage. The operation principle was experimentally confirmed with 0- and π-phase-different optical pairs generated by an intensity modulator. Also, it has been applied for a high-speed signal sensing with a high-resolution amplitude spectrum measurement method. A 12.5 Gbps signal sensing with 1/63 relatively low-speed photodetector (200 MHz) was demonstrated. © 2010 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.optcom.2010.08.018
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DOI ID：10.1016/j.optcom.2010.08.018, ISSN：0030-4018, SCOPUS ID：77957749952, Web of Science ID：WOS:000283704800030 - Photoinduced reorientation and polarization holography in photo-cross-linkable liquid crystalline polymer films with large birefringence
Nobuhiro Kawatsuki; Ayumi Yamashita; Mizuho Kondo; Taro Matsumoto; Tatsutoshi Shioda; Akira Emoto; Hiroshi Ono
Polymer, 巻：51, 号：13, 開始ページ：2849, 終了ページ：2856, 2010年06月
A new photo-cross-linkable liquid crystalline polymer (PLCP) comprised 4-methoxycinnamoyloxy groups connected with a bistolane side group was synthesized to investigate thermally enhanced photoinduced molecular reorientation of a thin film with linearly polarized (LP) 365. nm light exposure. Due to the axis-selective photoreaction of the cinnamate groups followed by the thermally induced self-organization, large molecular reorientation parallel to the polarization of LPUV light (S>0.6) and large birefringence at the non-resonance region (Δ n=0.34 at 632.8. nm) were obtained. The obtained Δ n value is the largest among transparent PLCPs in the visible region. The influence of the degree of photoreaction and the annealing temperature on the thermally enhanced molecular reorientation behavior was explored in detail. Finally, for an application of thin optical devices using the PLCP films, pure polarization holographic gratings with large birefringence, which showed periodic molecularly oriented structure, were fabricated using a 325. nm He-Cd laser in various polarization modes and characterized their optical properties. © 2010 Elsevier Ltd.
研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.polymer.2010.04.043
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DOI ID：10.1016/j.polymer.2010.04.043, ISSN：0032-3861, SCOPUS ID：77954817210 - Magneto-optical imaging and coercivity mapping of GdFe spin-valve structures
Takayuki Ishibashi; Terumasa Kosaka; Masayuki Naganuma; Tatsutoshi Shioda; Ken Ichi Aoshima; Nobuhiko Funabashi; Kenji MacHida; Kiyoshi Kuga; Naoki Shimidzu
Journal of Applied Physics, 巻：107, 号：9, 2010年05月
GdFe spin-valve structures, Si/bottom electrode/TbFeCo/CoFe (1 nm)/Cu (6 nm)/GdFe (10 nm)/Ru, with dimensions of 20×20 μ m2 were investigated by a magneto-optical imaging technique. In a parallel configuration, i.e., a configuration in which the magnetization directions of GdFe and TbFeCo layers are parallel, the coercivity (Hc) decreases when nucleation centers are present in the patterns. In the antiparallel configuration, although few nucleation centers are present the deviation in Hc is greater than that in the parallel configuration. © 2010 American Institute of Physics.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1063/1.3367980
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DOI ID：10.1063/1.3367980, ISSN：0021-8979, SCOPUS ID：77951689530 - Application of dual-heterodyne mixing method to simple dispersion measurement using dispersion compensator
H. Ishimaru; T. Yamazaki; H. Ono; T. Shioda
Technical Digest - 15th OptoElectronics and Communications Conference, OECC2010, 開始ページ：594, 終了ページ：595, 2010年
A direct chromatic dispersion measurement with dual-heterodyne mixing method (relative phase detection) is proposed. The sample dispersion can be measured as amount of compensation by monitoring relative phase, which enables direct measurement without wavelength sweeping.
研究論文（国際会議プロシーディングス）
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SCOPUS ID：78649272746 - High-speed signal detection with dual-heterodyne mixing method
T. Yamazaki; H. Ono; T. Shioda
Technical Digest - 15th OptoElectronics and Communications Conference, OECC2010, 開始ページ：294, 終了ページ：295, 2010年
We have proposed a novel phase and amplitude spectra measurement system, which was named as "Dual-Heterodyne Mixing Method." The experimental demonstration is presented by 12.5 Gbps BPSK signal detection by 1/63 low-speed detector circuits.
研究論文（国際会議プロシーディングス）
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SCOPUS ID：78649296446 - High-resolution spectroscopy using interleaved optical frequency comb
Tatsutoshi Shioda; Kenichi Fujii; Ken Kashiwagi; Takashi Kurokawa
Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference: 2010 Laser Science to Photonic Applications, CLEO/QELS 2010, 2010年
We propose high-resolution spectroscopy based on the sweep of the interleaved optical frequency comb by an optical phase modulator. Fine spectrum of HCN gas has been successfully measured with 1 MHz resolution over 4 THz frequency range. © 2010 Optical Society of America.
研究論文（国際会議プロシーディングス）
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eISSN：2162-2701, SCOPUS ID：77957597555 - 12.5Gbps PSK signal detection using 200MHz detector with dual heterodyne mixing method
Tatsutoshi Shioda; Toshiaki Yamazaki; Hiroshi Ono
Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference: 2010 Laser Science to Photonic Applications, CLEO/QELS 2010, 2010年
Novel method for relative phase measurement between optical longitudinal modes has been proposed and named as "dual heterodyne mixing method". It was applied for 12.5GBps BPSK signal sensing by 200MHz low-speed receiver. © 2010 Optical Society of America.
研究論文（国際会議プロシーディングス）
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eISSN：2162-2701, SCOPUS ID：77957583476 - High-resolution spectroscopy based on optical phase modulator and optical frequency comb
Tatsutoshi Shioda; Takayoshi Mori; Tatsuya Sugimoto; Yosuke Tanaka; Takashi Kurokawa
Optics Communications, 巻：282, 号：14, 開始ページ：2909, 終了ページ：2912, 2009年07月
A phase modulation of an optical frequency comb has been applied to measure a fine spectrum in the 1.5 μm wavelength range by the optical heterodyne-detection method. The measurement frequency range covered 25 GHz, which satisfies the frequency interval of the optical frequency comb, with a spectral resolution of 1 MHz. © 2009 Elsevier B.V. All rights reserved.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/j.optcom.2009.03.065
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DOI ID：10.1016/j.optcom.2009.03.065, ISSN：0030-4018, CiNii Articles ID：80020411507, SCOPUS ID：66249089171 - Elastic continuum analysis and diffraction properties of two-dimensional liquid crystalline grating cells
Hiroshi Ono; Masakata Hishida; Akira Emoto; Tatsutoshi Shioda; Nobuhiro Kawatsuki
Journal of the Optical Society of America B: Optical Physics, 巻：26, 号：6, 開始ページ：1151, 終了ページ：1156, 2009年06月
A detailed analysis of two-dimensional liquid crystalline grating cells is presented. Crossed liquid crystalline gratings were prepared using two kinds of photo-alignment polymers, i.e., poly(vinyl cinnamate) (PVCi) and photocrosslinkable polymer liquid crystal (PCLC). The effects of the anchoring strength of photo-alignment polymer films and crossing angles of grating vectors on one pair of photo-alignment substrates were extensively investigated using elastic continuum analysis, Jones calculus, and diffraction theory. The anchoring strength of our PCLC film was sufficiently strong, and experimental observation was in good agreement with the theoretical values obtained assuming the strong anchoring (fixed boundary conditions), although PCLC still has limits with the capability of photo-alignment of the low-molar-mass liquid crystals. ©2009 Optical Society of America.
研究論文（学術雑誌）
DOI：https://doi.org/10.1364/JOSAB.26.001151
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DOI ID：10.1364/JOSAB.26.001151, ISSN：0740-3224, SCOPUS ID：67650751412 - Power line monitoring system using fiber optic power supply
Yosuke Tanaka; Tatsutoshi Shioda; Takashi Kurokawa; Junji Oka; Kazuyuki Ueta; Toshiharu Fukuoka
Optical Review, 巻：16, 号：3, 開始ページ：257, 終了ページ：261, 2009年05月, ［査読有り］
We propose a novel power-line-monitoring system using optical fibers for transmitting power as well as signal. The principle is experimentally confirmed with a system composed of a monitoring side with a 1.5-μm laser diode, transmission line of a single mode fiber, and a sensing side having an efficient photovoltaic (PV) cell, electrical junction sensor, and low power liquid crystal optical modulator (LCOM). The PV cell generates the electrical power in the sensing side with a conversion efficiency of 20%. The LCOM is driven with low power of less than 50 μW, modulates the laser light with a signal indicating the power line condition, and transmits the optical signal. The developed sensing unit produces an optical signal having an extinction ratio of 15 dB with low optical power of 1.8 mW. Five systems were in operation for two years, faithfully monitoring the oil pressure in electrical cables every 20 min without incident. © 2009 The Optical Society of Japan.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1007/s10043-009-0048-x
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DOI ID：10.1007/s10043-009-0048-x, ISSN：1340-6000, eISSN：1349-9432, CiNii Articles ID：10025304540, SCOPUS ID：67149103682 - Effects of phase shift between two photo-alignment substrates on diffraction properties in liquid crystalline grating cells
Hiroshi Ono; Takeshi Shinmachi; Akira Emoto; Tatsutoshi Shioda; Nobuhiro Kawatsuki
Applied Optics, 巻：48, 号：2, 開始ページ：309, 終了ページ：315, 2009年01月
Diffractive optical devices using low-molar-mass liquid crystals are of great important for realizing numerical optical functions such as optical memory and information systems. In the present study the liquid crystalline gratings have been fabricated using a pair of photo-alignment substrates, and effects of the phase shift between the two photo-alignment substrates on the diffraction properties have been investigated. The liquid crystalline grating has been constructed with variable polarization dependence that can be controlled by the phase shift between the two photo-alignment substrates and twisted angles of the nematic directors. The theoretical considerations were also performed using the elastic continuum theory, Jones calculus, and diffraction theory. A guiding principle that controls the diffraction properties of the liquid crystalline grating cell was successfully presented. © 2009 Optical Society of America.
研究論文（学術雑誌）
DOI：https://doi.org/10.1364/AO.48.000309
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DOI ID：10.1364/AO.48.000309, ISSN：1559-128X, eISSN：1539-4522, SCOPUS ID：60849109235 - Transmission and reflection phase gratings formed in azo-dye-doped chiral nematic liquid crystals
Tomoyuki Sasaki; Akira Emoto; Tatsutoshi Shioda; Hiroshi Ono
Applied Physics Letters, 巻：94, 号：2, 2009年
Transmission and reflection gratings were simultaneously formed in azo-dye-doped chiral nematic liquid crystals (N* LCs) with planar alignment. The formation process is based on a phototuning of the Bragg reflection band of the N* LC. The helical pitch of the photoreactive N* LC was spatially controlled with intensity variation of interference light. The resultant periodic structure showed both transmissive and reflective diffractions due to the spatially modulated light intensities. The observed dependence of diffraction efficiencies on the polarization states of the probe beam was well explained by considering a spatial modulation of the helical pitch. © 2009 American Institute of Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.3072363
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DOI ID：10.1063/1.3072363, ISSN：0003-6951, SCOPUS ID：58349086208 - Vector holograms using radially polarized light
Hiroshi Ono; Hiroyuki Wakabayashi; Tomoyuki Sasaki; Akira Emoto; Tatsutoshi Shioda; Nobuhiro Kawatsuki
Applied Physics Letters, 巻：94, 号：7, 2009年
We have demonstrated the vector holograms using the radially polarized light. The inhomogeneous polarized light well controlled the spatial distribution of the optical anisotropy in the solid state polymeric materials. The theoretical calculation revealed formation mechanism and optical properties of the vector holograms. © 2009 American Institute of Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.3089236
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DOI ID：10.1063/1.3089236, ISSN：0003-6951, SCOPUS ID：60749106733 - One- and two-dimensional anisotropic diffractive gratings formed by periodic orthogonal molecular alignment in a hydrogen-bonded liquid crystalline polymer
Akira Emoto; Sayaka Manabe; Tatsutoshi Shioda; Hiroshi Ono; Nobuhiro Kawatsuki
Journal of Applied Physics, 巻：105, 号：10, 2009年
Anisotropic diffractive gratings having periodic orthogonal molecular alignments are formed by a linearly polarized ultraviolet (LPUV) exposure through a photomask in hydrogen (H)-bonding liquid crystalline polymers (H-LCPs) using a unique molecular reorientation behavior. H-bonded side-chain groups of H-LCPs play an important role in the molecular reorientation and the resultant optical anisotropy originating from an intermolecular network composition. To evaluate its potential for optical applications, one- and two-dimensional diffractive gratings were fabricated and analyzed by both polarization optical microscopy and diffraction characteristics. As a result, anisotropic gratings using H-LCP were obtained with a high diffraction efficiency that was 80% of the theoretical maximum efficiency (33.9%) of thin diffractive gratings. Results of experimental and theoretical investigation reveal that the resultant molecular direction and optical anisotropy are generated and controlled by LPUV exposure. © 2009 American Institute of Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.3129522
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DOI ID：10.1063/1.3129522, ISSN：0021-8979, SCOPUS ID：66549087008 - Two-dimensional patterning of colloidal crystals by means of lateral autocloning in edge-patterned cells
Akira Emoto; Tadayoshi Kamei; Tatsutoshi Shioda; Nobuhiro Kawatsuki; Hiroshi Ono
Journal of Applied Physics, 巻：105, 号：12, 2009年
We report the experimental results of two-dimensional patterning of colloidal crystals using edge-patterned cells. Solvent evaporation of a colloidal suspension from the edge of the cell induces self-organized crystallization of spherical colloidal particles. From a reservoir of colloidal suspension in the cell, different colloidal suspensions are injected repetitively. An edge-patterned substrate is introduced into the cell as an upper substrate. As a result, different colloidal crystals are alternately stacked in the lateral direction according to the edge pattern. The characteristics of cloning formation are specifically showed including deformations from the original pattern. This two-dimensional patterning of three-dimensional colloidal crystals by means of lateral autocloning is promising for the development of photonic crystal arrays for use in optic and photonic devices. © 2009 American Institute of Physics.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1063/1.3151710
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DOI ID：10.1063/1.3151710, ISSN：0021-8979, SCOPUS ID：67650269800 - Large birefringence and polarization holographic gratings formed in photocross-linkable polymer liquid crystals comprising bistolane mesogenic side groups
Akira Emoto; Taro Matsumoto; Ayumi Yamashita; Tatsutoshi Shioda; Hiroshi Ono; Nobuhiro Kawatsuki
Journal of Applied Physics, 巻：106, 号：7, 2009年
Polarization gratings with large birefringence are formed in photoreactive polymer liquid crystals with bistolane moiety and terminal cinnamic acid moiety by the use of polarized ultraviolet interference light and subsequent annealing. The polarized ultraviolet light causes the axis-selective photoreaction between the cinnamic acid groups and subsequent annealing induce the reorientation of peripheral molecules without cross-linking along the cross-linked groups. Long bistolane mesogenic moiety exhibits large birefringence in comparison with a biphenyl mesogenic moiety, the value of the induced birefringence in the bistolane mesogenic liquid crystalline (LC) polymer is strongly dependent on both the grating constant and the wavelength of the reconstruction light. © 2009 American Institute of Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.3234385
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DOI ID：10.1063/1.3234385, ISSN：0021-8979, SCOPUS ID：70350102368 - Reconstruction of polarized optical images in two- and three-dimensional vector holograms
Hiroshi Ono; Kakeru Suzuki; Tomoyuki Sasaki; Takanori Iwato; Akira Emoto; Tatsutoshi Shioda; Nobuhiro Kawatsuki
Journal of Applied Physics, 巻：106, 号：8, 2009年
In the present paper, we extensively study the optical diffraction in two- and three-dimensional vector holograms and demonstrate the reconstruction of polarized optical images recorded in azobenzene-containing amorphous polymers (AP) and polymer-dissolved liquid-crystalline composites (PDLCC). The polarization states of the interference light are not modulated in the isotropic AP films, while modulated in the anisotropic PDLCC films. The information of the polarized optical image is recorded as the polarization induced anisotropy in the AP and PDLCC medium and is reconstructed as the polarized optical images. The theoretical consideration well explained the characteristics of the reconstructed polarized optical images from both two- and three-dimensional vector holograms. © 2009 American Institute of Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.3247974
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DOI ID：10.1063/1.3247974, ISSN：0021-8979, SCOPUS ID：70350702561 - High-resolution spectroscopy based on interleaved optical frequency comb
Tatsutoshi Shioda; Kenichi Fujii; Ken Kashiwagi; Takashi Kurokawa
Optics InfoBase Conference Papers, 2009年
We propose high-resolution spectroscopy based on the sweep of optical frequency comb using an optical phase modulator. Optical interleavers are introduced to detect one peak from dense comb peaks with high signal-to-noise ratio. © 2009 IEEE.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEOPR.2009.5292332
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DOI ID：10.1109/CLEOPR.2009.5292332, eISSN：2162-2701, SCOPUS ID：84894062113 - Novel relative phase detection using dual heterodyne mixing method and its application to high-speed waveform measurement
Toshiaki Yamazaki; Hiroshi Ono; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 2009年
Novel method of the relative phase detection between optical longitudinal modes has been proposed. It was applied for a high-speed signal sensing with a high resolution amplitude measurement under the principle of time-space conversion. © 2009 IEEE.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEOPR.2009.5292334
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84894060797&origin=inward
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DOI ID：10.1109/CLEOPR.2009.5292334, eISSN：2162-2701, SCOPUS ID：84894060797 - Scanless profilometry by means of VIPA installed optical interferometer
Takashi Morisaki; Hiroshi Ono; Tatsutoshi Shioda
Optics InfoBase Conference Papers, 2009年
A VIPA installed optical interferometer for scanless profilometry is proposed by displaying the applied delay time to a line-image sensor. The delay time was carried on spatially separated combs generated by the VIPA. © 2009 IEEE.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEOPR.2009.5292338
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DOI ID：10.1109/CLEOPR.2009.5292338, eISSN：2162-2701, SCOPUS ID：84894029782 - High-resolution spectroscopy combined with optical frequency comb and heterodyne detection method
Tatsutoshi Shioda; Kenichiro Fujii; Ken Kashiwagi; Takashi Kurokawa
Optics InfoBase Conference Papers, 巻：27, 号：7, 開始ページ：1487, 終了ページ：1491, 2009年
We have proposed high resolution spectroscopy based on an optical frequency comb and heterodyne detection method, whose measurement frequency range has already achieved to be 3 THz (1530nm~1560nm) with a spectral resolution of less than 1 MHz. Also, the absolute frequency axis is guaranteed less than 1MHz. In this presentation, we will show the experimental results including dynamic range of the proposed system. © 2009 Optical Society of America.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/cleo.2009.cmii3
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DOI ID：10.1364/cleo.2009.cmii3, ISSN：0740-3224, eISSN：2162-2701, SCOPUS ID：85088718357 - Generation of 100-Gb/s packets having 8-bit return-to-zero patterns using an optical pulse synthesizer with a lookup table
Yosuke Tanaka; Ryo Kobe; Tatsutoshi Shioda; Hiroyuki Tsuda; Takashi Kurokawa
IEEE Photonics Technology Letters, 巻：21, 号：1, 開始ページ：39, 終了ページ：41, 2009年, ［査読有り］
Real-time generation and switching of 100-Gb/s optical packets with 8-bit return-to-zero pulse patterns was realized by constructing a lookup table of the control signal for use by an optical pulse synthesizer. The resulting packet patterns agreed well with the design specifications. The reproducibility of a packet pattern for a given control current was also confirmed. © 2009 IEEE.
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1109/LPT.2008.2007914
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DOI ID：10.1109/LPT.2008.2007914, ISSN：1041-1135, SCOPUS ID：71249135948, Web of Science ID：WOS:000263480100013 - Multicarrier light source with 50 GHz spacing and its application in dense wavelength division multiplexing system
Yosuke Tanaka; Yu Matsunaga; Takahiro Hoshi; Tatsutoshi Shioda; Takashi Kurokawa
Japanese Journal of Applied Physics, 巻：48, 号：9 Part 3, 開始ページ：09LF04, 2009年
We developed a multicarrier light source with a 50GHz spacing using a 25-GHz-spacing comb generator and 50-GHz-spacing comb filter. The comb generator was composed of a dual-drive Mach-Zehnder (MZ) modulator with push-pull operation and a phase modulator (PM). The MZ modulator and PM were overdriven at 12.5GHz and at a harmonic of 25 GHz, respectively. We produced 23 comb lines with a flatness below 1.7 dB, which were demultiplexed to produce 11 channel carriers. The relative intensity noise for each carrier was almost equal to that of the seed laser diode (LD). The crosstalk between neighboring channels was less than -35 dB. It was also confirmed that our comb generator is independent of the wavelength of the seed LD and can cover approximately one hundred channels of the entire C-band with eight seed LDs. Experiments on transmission over 100km achieved a bit error rate of 10-12 for the 10 Gbps non-return-to-zero signal. © 2009 The Japan Society of Applied Physics.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.48.09LF04
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DOI ID：10.1143/JJAP.48.09LF04, ISSN：0021-4922, eISSN：1347-4065, SCOPUS ID：77952700315 - Fiber transmission characteristics of optical short pulses generated by optical pulse synthesizer
Ken Kashiwagi; Yuichiro Kodama; Ryo Kobe; Tatsutoshi Shioda; Yosuke Tanaka; Takashi Kurokawa
Japanese Journal of Applied Physics, 巻：48, 号：9 Part 3, 開始ページ：09LF02, 2009年
In this study, we experimentally characterize optical short-pulse transmission through single-mode fibers. The initial pulses were precisely generated by an optical pulse synthesizer. The optical pulse synthesizer provides line-by-line phase and intensity modulations to individual channels in optical frequency combs and generates precise arbitral pulses. Pulse shaping enables the experimental evaluation of pulse transmission along the fibers under various initial pulse conditions, and the pulse evolution of Gaussian and sech2 pulses through standard single-mode fibers (SMFs) was experimentally investigated. The sech2 pulses had smaller pulse broadening and distortion than the Gaussian ones at the same pulse width and peak power. The sech2 pulses nearly maintained their initial time bandwidth products (TBPs). The required pulse peak power for soliton transmission matched the theoretical value. © 2009 The Japan Society of Applied Physics.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.48.09LF02
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DOI ID：10.1143/JJAP.48.09LF02, ISSN：0021-4922, eISSN：1347-4065, SCOPUS ID：77952695485 - Supercontinuum comb generation using optical pulse synthesizer and highly nonlinear dispersion-shifted fiber
Samuel Choi; Naoyuki Tamura; Ken Kashiwagi; Tatsutoshi Shioda; Yosuke Tanaka; Takashi Kurokaway
Japanese Journal of Applied Physics, 巻：48, 号：9 Part 3, 2009年, ［査読有り］
We propose a novel supercontinuum (SC) generation technology using an optical pulse synthesizer and highly nonlinear dispersion-shifted fiber. The optical pulse synthesizer enables us to reshape seed pulses optimized for broadband SC generation. 25.0 and 12.5GHz SC combs were successfully generated by propagating synthesized seed pulses in the highly nonlinear fiber. We investigated how seed pulse conditions including shape, peak power, repetition rate, and center wavelength affect SC spectral bandwidth. We also evaluated interferometric signal waveforms from a Michelson interferometer using the generated SC comb as the light source. Interferometric peak width improved to 35.5 μm when peak power reached 7.9W for the Gaussian pulse-based SC comb. Numerical simulation results almost agreed with experimental results. The difference between SC combs generated from Gaussian and sech2 pulses was confirmed by the simulations. © 2009 The Japan Society of Applied Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.48.09LF01
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DOI ID：10.1143/JJAP.48.09LF01, ISSN：0021-4922, eISSN：1347-4065, SCOPUS ID：77952683887, Web of Science ID：WOS:000270565200021 - Light wave propagation and Bragg diffraction in thick polarization gratings
Hiroshi Ono; Takuya Sekiguchi; Akira Emoto; Tatsutoshi Shioda; Nobuhiro Kawatsuki
Japanese Journal of Applied Physics, 巻：47, 号：10 PART 1, 開始ページ：7963, 終了ページ：7967, 2008年10月
Light wave propagation in thick polarization gratings has been studied using the finite-difference time-domain (FDTD) method. The diffraction properties of the polarization Bragg gratings were strongly dependent on both the polarization state and incident angle of the probe beam. These characteristics were well explained by the FDTD calculation and the subsequent Fourier transformation. The FDTD calculation also revealed the light electric field near and/or in the polarization Bragg gratings. © 2008 The Japan Society of Applied Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.47.7963
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DOI ID：10.1143/JJAP.47.7963, ISSN：0021-4922, eISSN：1347-4065, SCOPUS ID：62249153908 - Analog and digital optical pulse synthesizers using arrayed-waveguide gratings for high-speed optical signal processing
Hiroyuki Tsuda; Yosuke Tanaka; Tatsutoshi Shioda; Takashi Kurokawa
Journal of Lightwave Technology, 巻：26, 号：6, 開始ページ：670, 終了ページ：677, 2008年03月, ［査読有り］
In this paper, analog and digital optical pulse synthesizers using high-resolution arrayed-waveguide gratings (AWG) have been developed. The analog type of optical synthesizer consists of an AWG with an integrated 45°, curved-surfaced mirror, a 4-f lens system, and an optically addressable spatial light modulator. The effective frequency resolution is 14.5 GHz. A dispersion compensation experiment is successfully carried out and a transform-limited short pulse has been obtained. This digital type of optical synthesizer comprises 30 frequency separated channels with a spacing of 12.5 GHz, where each channel includes an amplitude modulator and a phase modulator. The rectangular-shaped pulse is generated with this pulse synthesizer, together with a 12.5-GHz-spacing, optical frequency comb. The synthesizer can generate an optical pulse with any waveform. Moreover, using periodic characteristics of the pulse synthesizer, a 250-GHz repetition rate pulse train was generated, in combination with an ultrawideband, waveguide type of Fabry-Perot electrooptic modulator. © 2008 IEEE.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1109/JLT.2007.916580
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DOI ID：10.1109/JLT.2007.916580, ISSN：0733-8724, CiNii Articles ID：80019492655, SCOPUS ID：42649093834 - Three-dimensional microscopic interferometer by frequency sweep of supercontinuum frequency comb
Samuel Choi; Naoyuki Tamura; Ryo Kobe; Tatsutoshi Shioda; Yosuke Tanaka; Takashi Kurokawa
Optics InfoBase Conference Papers, 2008年
A three-dimensional microscopic interferometer by the interval frequency sweep of the supercontinuum frequency comb generated by an optical pulse synthesizer was demonstrated. The spectral bandwidth was 80 nm. The interferometric peak width was 35 μm. © 2006 Optical Society of America.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEO.2008.4551160
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DOI ID：10.1109/CLEO.2008.4551160, eISSN：2162-2701, SCOPUS ID：84898639626 - Frequency scanning spectroscopy of optical frequency comb with high-resolution on an absolute frequency axis
Tatsutoshi Shioda; Takayoshi Mori; Kenichiro Fujii; Yosuke Tanaka; Takashi Kurokawa
Optics InfoBase Conference Papers, 開始ページ：2229, 終了ページ：2230, 2008年, ［査読有り］
We propose high resolution spectroscopy based on a single-sideband optical modulator and an optical frequency comb technology. It has been confirmed experimentally that the spectral resolution and the frequency measurement range was digit of 1 MHz (10-5 nm) and 1 THz (10 nm), which is corresponding to the comb bandwidth, respectively. © 2008 Optical Society of America.
IEEE, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/QELS.2008.4552563
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DOI ID：10.1109/QELS.2008.4552563, eISSN：2162-2701, SCOPUS ID：84898640447, Web of Science ID：WOS:000260498401105 - Application of faraday rotator reflector and faraday rotator transmitter to profilometry and tomography
Tatsutoshi Shioda; Daisuke Moteki; Samuel Choi; Yosuke Tanaka; Takashi Kurokawa
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, 巻：46, 号：10 A, 開始ページ：6848, 終了ページ：6852, 2007年10月, ［査読有り］
The polarization compensation of a Faraday rotator reflector was quantitatively measured while applying mechanical stress to an optical fiber. A novel device called a Faraday rotator transmitter was developed to illuminate a sample. It was confirmed that the installation of both a Faraday rotator reflector and a Faraday rotator transmitter in a fiber-optic interferometer greatly improves the accuracy of film thickness measurements compared with measurements obtained using an interferometer that employed polarization- maintaining optical fibers. © 2007 The Japan Society of Applied Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.46.6848
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DOI ID：10.1143/JJAP.46.6848, ISSN：0021-4922, eISSN：1347-4065, SCOPUS ID：35348902457, Web of Science ID：WOS:000250266800082 - Frequency-comb-based interference microscope with a line-type image sensor
Samuel Choi; Tatsutoshi Shioda; Yosuke Tanaka; Takashi Kurokawa
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, 巻：46, 号：10 A, 開始ページ：6842, 終了ページ：6847, 2007年10月, ［査読有り］
We present a frequency-comb-based interferometric microscope using a broadband comb light source and a line-type image sensor for profilometry and optical tomography. A waveguide-type frequency comb generator and wavelength equalizer were introduced to broaden the comb spectrum. In this paper, we demonstrate the surface profilometry of a coin and the observation of a cross-sectional tomography image of transparent glass. The three-dimensional images were captured using a line-type image sensor without any mechanical moving parts with a frequency interval variation of 25 GHz. The dynamic range in the depth direction was about 1.4 mm and the measurement resolution was 35 p.m. The standard deviation of seven thickness measurements was 5 μm. © 2007 The Japan Society of Applied Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.46.6842
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DOI ID：10.1143/JJAP.46.6842, ISSN：0021-4922, eISSN：1347-4065, SCOPUS ID：35348861267, Web of Science ID：WOS:000250266800081 - Polarization fluctuation suppression and sensitivity enhancement of an optical correlation sensing system
H. B. Song; T. Suzuki; T. Fujimura; K. Nonaka; T. Shioda; T. Kurokawa
Measurement Science and Technology, 巻：18, 号：10, 開始ページ：3230, 終了ページ：3234, 2007年10月
Based on the optical pulse correlation measurement and differential detection technique, an optical fibre sensor with high time resolution has been developed. However, due to the birefringence in single mode fibre induced by the uneven thermal effect, polarization fluctuation in the correlation signal was observed. In order to suppress the polarization fluctuation in the correlation sensing system, a polarization-suppressed optical correlation sensing system is proposed by utilizing the birefringence compensation approach in a retraced fibre path using Faraday rotator mirror elements. The polarization fluctuation of the output correlation signals is suppressed by more than 15 dB. The results of temperature experiment indicate that the linearity between the temperature and differential signal is further improved. With the reflection of the mirror, a double-pass monitoring is established, which significantly enhances the sensitivities of the sensing system to temperature and strain. © 2007 IOP Publishing Ltd.
研究論文（学術雑誌）
DOI：https://doi.org/10.1088/0957-0233/18/10/S27
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DOI ID：10.1088/0957-0233/18/10/S27, ISSN：0957-0233, eISSN：1361-6501, SCOPUS ID：36749019656 - Resolution and noise factor of distance measurement using two-photon absorption process in photodetector
Yosuke Tanaka; Tatsutoshi Shioda; Mitsuo Takeda; Takashi Kurokawa
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, 巻：46, 号：8 A, 開始ページ：5331, 終了ページ：5337, 2007年08月, ［査読有り］
In this paper, we investigate the resolution, accuracy, and noise factor of distance measurement using intensity-modulated light and a photodetector with two-photon absorption (TPA) characteristics. Distance resolution and measurement accuracy are clarified theoretically and experimentally in terms of the sweeping range and the scanning step of the intensity-modulation frequency. The theory of accuracy improvement by signal processing known as the "Fourier transform method" is experimentally confirmed for the first time. The influence of a photodetector's temperature on measurement resolution is also made clear by the experiments. A high resolution is achieved by controlling the photodetector at a low temperature, which is explained from the temperature dependence of TPA sensitivity in the photodetector. In addition to these investigations, we discuss the advantage of the TPA-based distance measurement over other conventional methods such as optical time domain reflectometry from the viewpoints of cost and measurement performance. © 2007 The Japan Society of Applied Physics.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.46.5331
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=34547854760&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=34547854760&origin=inward
DOI ID：10.1143/JJAP.46.5331, ISSN：0021-4922, eISSN：1347-4065, CiNii Articles ID：150000049232, SCOPUS ID：34547854760 - 1 MHz-resolution spectroscopy based on light frequency sweeping using a single-sideband optical modulator
Tatsutoshi Shioda; Takeshi Yamamoto; Tatsuya Sugimoto; Yosuke Tanaka; Kaoru Higuma; Takashi Kurokawa
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, 巻：46, 号：6 A, 開始ページ：3626, 終了ページ：3629, 2007年06月, ［査読有り］
We propose high-resolution spectroscopy based on laser light frequency sweeping using an optical single-sideband modulator. It has been confirmed experimentally that the frequency stability of the light source and high-speed scanning are critical for obtaining high resolutions of up to 1 MHz. © 2007 The Japan Society of Applied Physics.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.46.3626
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=34547842110&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=34547842110&origin=inward
DOI ID：10.1143/JJAP.46.3626, ISSN：0021-4922, eISSN：1347-4065, CiNii Articles ID：150000048861, SCOPUS ID：34547842110 - 100-Gbps optical packets with 8-bit RZ pulse patterns generated by an optical pulse synthesizer
Yosuke Tanaka; Ryo Kobe; Shinsuke Takeda; Tatsutoshi Shioda; Hiroyuki Tsuda; Takashi Kurokawa
2007 33rd European Conference and Exhibition of Optical Communication, ECOC 2007, 2007年
We successfully generated optical packets by the feedback control of an optical pulse synthesizer. Arbitrary 8-bit RZ pulse packets with a bit rate of 100 Gbps were experimentally demonstrated.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1049/ic:20070166
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Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84931024064&origin=inward
DOI ID：10.1049/ic:20070166, SCOPUS ID：84931024064 - High-resolution spectroscopy using phase modulation of frequency comb light
Tatsutoshi Shioda; Takayoshi Mori; Tatsuya Sugimoto; Yosuke Tanaka; Takashi Kurokawa
Optics InfoBase Conference Papers, 2007年
A phase modulation of frequency comb light has been applied to measure a fine spectral line of H13C14N gas at 1.5 μm wavelength range with optical heterodyne-detection method. The measurement range successfully covered 25 GHz with a spectral resolution of 1 MHz. © CLEO Pacific Rim 2007.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEOPR.2007.4391671
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84899077572&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84899077572&origin=inward
DOI ID：10.1109/CLEOPR.2007.4391671, eISSN：2162-2701, SCOPUS ID：84899077572 - 10-Gbps DWDM transmission using multi-frequency light source with 50-GHz channel spacing
Takahiro Hoshi; Tatsutoshi Shioda; Yosuke Tanaka; Takashi Kurokawa
Optics InfoBase Conference Papers, 2007年
A multi-frequency light source with 50-GHz channel spacing was constructed based on optical frequency comb generation. The error-free 10-Gbps WDM transmission over 100-km was successfully achieved using the multi-frequency light source. © 2006 Optical Society of America.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/OFC.2007.4348636
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84899078770&origin=inward
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DOI ID：10.1109/OFC.2007.4348636, eISSN：2162-2701, SCOPUS ID：84899078770 - 100-km DWDM transmission with 50-GHz channel spacing using a frequency-comb light source
Takahiro Hoshi; Tatsutoshi Shioda; Yosuke Tanaka; Takashi Kurokawa
Optics InfoBase Conference Papers, 開始ページ：320, 終了ページ：321, 2007年, ［査読有り］
We investigated a multi-frequency light source with 50-GHz spacing based on the optical frequency comb generation. The error-free 10-Gbps DWDM transmission was successfully achieved over 100-km. © CLEO Pacific Rim 2007.
IEEE, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEOPR.2007.4391247
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84899080104&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84899080104&origin=inward
DOI ID：10.1109/CLEOPR.2007.4391247, eISSN：2162-2701, SCOPUS ID：84899080104, Web of Science ID：WOS:000256956600163 - Frequency comb based interference microscope with a line-type image sensor
Samuel Choi; Tatsutoshi Shioda; Yosuke Tanaka; Takashi Kurokawa
Optics InfoBase Conference Papers, 開始ページ：399, 終了ページ：400, 2007年, ［査読有り］
We present a frequency comb based interferometry with a broadband comb light source and a line-type image sensor for profilometry and optical tomography. The cross-sectional images were captured by varying the frequency interval of 25 GHz without mechanical shift. The resolution in depth direction was 35 μm. © CLEO Pacific Rim 2007.
IEEE, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEOPR.2007.4391287
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84899050227&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84899050227&origin=inward
DOI ID：10.1109/CLEOPR.2007.4391287, eISSN：2162-2701, SCOPUS ID：84899050227, Web of Science ID：WOS:000256956600203 - Accuracy of distance measurement based on two-photon absorption of Si-photodetector
Tatsuya Oiwa; Tatsutoshi Shioda; Yosuke Tanaka; Mitsuo Takeda; Takashi Kurokawa
Optics InfoBase Conference Papers, 開始ページ：405, 終了ページ：+, 2007年, ［査読有り］
We have successfully measured a space distance with the accuracy of less than 10-5 based on TPA process in a silicon photodetector. The two signal processing technologies including the Fourier transform method and the curve fitting method were investigated. © CLEO Pacific Rim 2007.
IEEE, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEOPR.2007.4391290
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84899082063&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84899082063&origin=inward
DOI ID：10.1109/CLEOPR.2007.4391290, eISSN：2162-2701, SCOPUS ID：84899082063, Web of Science ID：WOS:000256956600206 - Generation of 100-Gbps optical packets with 8-bit RZ pulse patterns using an optical pulse synthesizer
Ryo Kobe; Shinsuke Takeda; Tatsutoshi Shioda; Yosuke Tanaka; Hiroyuki Tsuda; Takashi Kurokawa
Optics InfoBase Conference Papers, 開始ページ：1067, 終了ページ：+, 2007年, ［査読有り］
We successfully demonstrated a generation of 100-Gbps optical packets with 8-bit RZ pulse patterns using an optical pulse synthesizer integrating an arrayed waveguide grating, phase modulators and amplitude modulators. © CLEO Pacific Rim 2007.
IEEE, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEOPR.2007.4391623
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84899080692&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84899080692&origin=inward
DOI ID：10.1109/CLEOPR.2007.4391623, eISSN：2162-2701, SCOPUS ID：84899080692, Web of Science ID：WOS:000256956600539 - Generation of 1.4 Gbps BPSK signal with 22 GHz millimeter wave carrier using optical homodyne detection
Nobuyoshi Shouji; Yosuke Tanaka; Tatsutoshi Shioda; Takashi Kurokawa
Optics InfoBase Conference Papers, 開始ページ：332, 終了ページ：333, 2007年, ［査読有り］
We proposed a novel method of generating PSK signal for millimeter waves and experimentally generated 1.4 Gbps PSK signal for 22 GHz millimeter wave. The BPSK signal was produced by modulating an optical millimeter wave with a MZ push-pull modulator at 1.4 Gbps and detecting it with optical homodyne technique. © CLEO Pacific Rim 2007.
IEEE, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEOPR.2007.4391253
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84899129198&origin=inward
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DOI ID：10.1109/CLEOPR.2007.4391253, eISSN：2162-2701, SCOPUS ID：84899129198, Web of Science ID：WOS:000256956600169 - Frequency-comb-based interferometer for profilometry and tomography
Choi Samuel; Mitsufumi Yamamoto; Daisuke Moteki; Tatsutoshi Shioda; Yosuke Tanaka; Takashi Kurokawa
Optics Letters, 巻：31, 号：13, 開始ページ：1976, 終了ページ：1978, 2006年07月, ［査読有り］
Novel interferometry technique using a frequency-comb light source is proposed for surface profilometry and tomography of discontinuous objects. Surface profile measurement is performed by sweeping the comb interval frequency without mechanical scanning. Step heights of 0.5 and 1.0mm are successfully measured by use of the scheme with 9 µm accuracy. © 2006 Optical Society of America.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1364/OL.31.001976
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DOI ID：10.1364/OL.31.001976, ISSN：0146-9592, eISSN：1539-4794, CiNii Articles ID：80019047219, PubMed ID：16770404, SCOPUS ID：33749342416 - Waveform-controllable optical pulse generation using an optical pulse synthesizer
D. Miyamoto; K. Mandai; T. Kurokawa; S. Takeda; T. Shioda; H. Tsuda
IEEE Photonics Technology Letters, 巻：18, 号：5, 開始ページ：721, 終了ページ：723, 2006年03月
We have proposed an optical pulse synthesizer comprising of optical modulators and an arrayed waveguide grating. This system can generate arbitrary waveform pulses in combination with a broad-band optical frequency comb. We achieved the generation of the Gaussian pulses with a width of 4.7 ps, double-Gaussian pulses, and rectangular-shaped pulses by arbitrary waveform pulse synthesis, at the high repetition rate of 10 GHz. © 2006 IEEE.
研究論文（学術雑誌）
DOI：https://doi.org/10.1109/LPT.2006.870080
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=33748777041&origin=inward
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DOI ID：10.1109/LPT.2006.870080, ISSN：1041-1135, SCOPUS ID：33748777041 - Fiber optic remote digital temperature sensor based on laser powering
Yosuke Tanaka; Muneyuki Nakagawa; Takeshi Nishimura; Tatsutoshi Shioda; Takashi Kurokawa; Yoshiyuki Matsuda; Kazuo Nosaka
Optics InfoBase Conference Papers, 2006年
We proposed and demonstrated a novel fiber-optic remote temperature sensor employing a digital sensor-IC and laser-powering. A low power system was realized by introducing a liquid-crystal optical modulator for transforming the IC-signal into the optical. © 2006 OSA/OFS 2006.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/ofs.2006.tue36
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85087599418&origin=inward
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DOI ID：10.1364/ofs.2006.tue36, eISSN：2162-2701, SCOPUS ID：85087599418 - Polarization stabilized optical fiber sensor with high time resolution based on optical pulse correlation and FRR
H. B. Song; T. Suzuki; K. Nonaka; T. Shioda; T. Kurokawa
Optics InfoBase Conference Papers, 2006年
A polarization stabilized high time resolution optical fiber sensor based on correlation monitoring, differential detection and Faraday Rotator Reflector is proposed. A time resolution of about 0.02 ps and good polarization stability were observed. © 2006 Optical Society of America.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/ofs.2006.the17
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85087189008&origin=inward
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DOI ID：10.1364/ofs.2006.the17, eISSN：2162-2701, SCOPUS ID：85087189008 - Long fiber reflectometry by use of two-photon absorption process in Si-APD
Yosuke Tanaka; Masanori Akiyama; Tatsutoshi Shioda; Takashi Kurokawa
Optics InfoBase Conference Papers, 2006年
We demonstrate a fiber reflectometry using the two-photon absorption process in a Si-APD. Reflectivity distribution for 10km fiber is measured with accuracy better than 0.1m and resolution better than 3m. © 2006 OSA/OFS 2006.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/ofs.2006.thc3
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85085403648&origin=inward
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DOI ID：10.1364/ofs.2006.thc3, eISSN：2162-2701, SCOPUS ID：85085403648 - Common-path achromatic interferometer-coronagraph: Nulling of polychromatic light
Alexander V. Tavrov; Yosuke Kobayashi; Yosuke Tanaka; Tatsutoshi Shioda; Yukitoshi Otani; Takashi Kurokawa; Mitsuo Takeda
Optics Letters, 巻：30, 号：17, 開始ページ：2224, 終了ページ：2226, 2005年09月, ［査読有り］
A three-dimensional common-path interferometer is proposed, which can achromatically null out an on-axis source while it maintains the detectability of an off-axis source. A geometric phase in the three-dimensional interferometer introduces an achromatic π-phase shift to the light from the on-axis source, such that destructive interference nulls out the axial light at one of the ports of the interferometer. Light from the off-axis source, which is exempt from the π-phase shift, comes out from both ports with equal intensity. The common-path scheme makes the system highly immune to environmental disturbances. © 2005 Optical Society of America.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1364/OL.30.002224
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DOI ID：10.1364/OL.30.002224, ISSN：0146-9592, CiNii Articles ID：30011699421, SCOPUS ID：25144431981 - Orientation of liquid crystal molecules evaporated onto rubbed and photoaligned polymer surfaces
Tatsutoshi Shioda; Yoshinori Okada; Yoichi Takanishi; Ken Ishikawa; Byoungchoo Park; Hideo Takezoe
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, 巻：44, 号：5 A, 開始ページ：3103, 終了ページ：3110, 2005年05月
Second-harmonic generation (SHG) and polarized ultraviolet-visible (UV-VIS) absorption have been used to study the orientational distribution function of 5CB (4′-n-pentyl-4-cyanobiphenyl) liquid crystal (LC) molecules adsorbed on rubbed and photoaligned photoisomerizable polyamic acid layers. The simultaneous analysis of SHG and polarized UV-VIS absorption data using the maximum entropy method shows that the anisotropic distribution of 5CB molecules along the rubbing direction tilts up from the surface plane as the molecular density increases. More interestingly, the anisotropy is relatively low at the first stage of the evaporation and becomes gradually pronounced, indicating an important role played by the long-range intermolecular interaction among LC molecules for LC surface alignment. No orientation formation of non-liquid crystalline 4CB (4′-n-butyl-4-cyanobiphenyl) molecules on the treated surfaces supports this conclusion. It is important to emphasize that a relatively small fraction of molecules contribute to give a polar order, but the rest form dimers even at the early stage of the evaporation. This tendency is particularly marked on the photoaligned surface; no SHG activity arises irrespective of the amount of evaporated molecules. © 2005 The Japan Society of Applied Physics.
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JJAP.44.3103
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DOI ID：10.1143/JJAP.44.3103, ISSN：0021-4922, SCOPUS ID：22544474194 - Ultrahigh-resolution spectroscopy using optical single-sideband modulator and fiber grating laser
Takeshi Yamamoto; Mitsufumi Yamamoto; Yosuke Tanaka; Tatsutoshi Shioda; Takashi Kurokawa; Kaoru Higuma
Optics InfoBase Conference Papers, 2005年
A novel method of ultrahigh-resolution spectroscopy has been developed by means of an optical single-sideband (SSB) modulator as an optical frequency shifter and a fiber grating laser with narrow line-width. The modulation frequency of the optical SSB modulator is electrically scanned by an RF-generator over several GHz, which sweeps the frequency of the probe light without mode hopping. The experimental result successfully showed MHz digit of resolution. © 2005 Optical Society of America.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/ipra.2005.iwg1
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85087189586&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85087189586&origin=inward
DOI ID：10.1364/ipra.2005.iwg1, eISSN：2162-2701, SCOPUS ID：85087189586 - Real-time shaping of ultra-short optical pulses using an arrayed-waveguide-grating and spatial light modulator
Hiroyuki Aoki; Koichi Aizawa; Tatsutoshi Shioda; Yosuke Tanaka; Takashi Kurokawa; Hiroyuki Tsuda
Optics InfoBase Conference Papers, 2005年
Real time shaping of a pulse waveform was demonstrated by means of arrayed waveguide grating and spatial light modulator. This system had 15 GHz of resolution and 3.8THz of free spectral range, which enable to shape the ultra-short optical pulses from 0.3 ps to 30 ps. Furthermore, it was successfully demonstrated that this system can compensate the dispersion of short pulses up to ±3.0 ps/nm in real time. © 2005 Optical Society of America.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/ipra.2005.iwa6
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85087606201&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85087606201&origin=inward
DOI ID：10.1364/ipra.2005.iwa6, eISSN：2162-2701, SCOPUS ID：85087606201 - Optical frequency comb generation using dual frequency optical phase modulation
Mitsufumi Yamamoto; Yosuke Tanaka; Tatsutoshi Shioda; Takashi Kurokawa; Kaoru Higuma
Optics InfoBase Conference Papers, 2005年
We have demonstrated a novel scheme of wide and fiat optical comb generation by driving a phase modulator with fundamental and harmonic signals. The experimental results have been evaluated with numerical simulation. 17 - 29 peaks in fiat comb with about 10 GHz intervals were experimentally obtained, which showed good agreement with the results of simulation. © 2005 Optical Society of America.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1364/ipra.2005.ituf5
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85088757741&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85088757741&origin=inward
DOI ID：10.1364/ipra.2005.ituf5, eISSN：2162-2701, SCOPUS ID：85088757741 - A novel profilometry using frequency comb light source
Samuel Choi; Mitsufumi Yamamoto; Daisuke Moteki; Tatsutoshi Shioda; Yosuke Tanaka; Mitsuo Takeda; Takashi Kurokawa
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, 巻：2005, 開始ページ：1688, 終了ページ：1690, 2005年
A novel profilometry using a frequency comb light source is proposed. This method realizes step height measurement without mechanical scanning. We have confirmed the system with high accuracy with this method.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEOPR.2005.1569855
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=33847095119&origin=inward
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DOI ID：10.1109/CLEOPR.2005.1569855, SCOPUS ID：33847095119 - 10, 20 and 30 GHz repetition rate optical pulse generation based on a AWG with integrated phase and intensity modulators
Shinsuke Takeda; Koichi Aizawa; Kohei Mandai; Yosuke Tanaka; Tatsutoshi Shioda; Hiroyuki Tsuda; Takashi Kurokawa
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, 巻：2005, 開始ページ：1200, 終了ページ：1201, 2005年
We demonstrate a generation of ultra short optical pulses with a repetition rate of 10, 20, and 30 GHz by means of optical frequency comb and arrayed waveguide grating with integrated phase and amplitude modulators.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEOPR.2005.1569698
Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=33847132863&origin=inward
Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=33847132863&origin=inward
DOI ID：10.1109/CLEOPR.2005.1569698, SCOPUS ID：33847132863 - Wavelength division multiplexer based on multi-mode interference waveguide
Shingo Kumagai; Tatsutoshi Shioda; Takashi Kurokawa
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, 巻：2005, 開始ページ：301, 終了ページ：303, 2005年
A 1300 nm / 1550 nm wavelength division multiplexer for subscriber networks is designed based on a multi-mode interference waveguide. A simple structure of the MMI slab waveguide makes easy passive optical joint with fibers.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEOPR.2005.1569427
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DOI ID：10.1109/CLEOPR.2005.1569427, SCOPUS ID：33847167086 - Optical reflectometry for 10 km fibers based on two photon absorption
Masanori Akiyama; Soichiro Imoto; Tatsutoshi Shioda; Yosuke Tanaka; Takashi Kurokawa
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest, 巻：2005, 開始ページ：1586, 終了ページ：1587, 2005年, ［査読有り］
We successfully measured the distance of 10 km optical fibers with an accuracy of 10-7. Furthermore, two reflection points with 2.5 m separating over 10 km far away was also successfully resolved.
IEEE, 英語, 研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1109/CLEOPR.2005.1569824
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DOI ID：10.1109/CLEOPR.2005.1569824, SCOPUS ID：33847101462, Web of Science ID：WOS:000236757900456 - Orientational transition of a bent-core dopant in an anticlinic liquid crystal matrix
Min Hua Zhu; M. R. Dodge; Tatsutoshi Shioda; Charles Rosenblatt; Dallas D. Parker; Julie M. Kim; Mary E. Neubert
Liquid Crystals, 巻：31, 号：10, 開始ページ：1381, 終了ページ：1386, 2004年10月
Small quantities of the bent-core mesogen P-7PIMB were dissolved in an anticlinic liquid crystal consisting of a mixture of left- and right-handed TFMHPOBC, with enantiomer excess X = 0.2. For bent-core concentrations above C = 3 wt %, differential scanning calorimetry shows the disappearance of the higher temperature synclinic phase, as well as the appearance of a new peak at a low temperature Tc. Polarized infrared absorption measurements indicate that the new DSC peak is due to an orientational transition of the bent-core molecules, analogous to the transition previously observed in a smectic A matrix. For T > Tc the plane of the bent-core molecules lies in the tilt plane of the anticlinic matrix, with the arrow (the symmetry axis) of the bent-core molecules parallel to the smectic layers. For T < Tc we deduce that the bent-core molecules lie within a single smectic layer, with the polar tilt of the arrow approximately equal to the polar tilt of the TFMHPOBC molecule and the vector connecting the two ends of the bent-core molecule perpendicular to the anticlinic tilt plane. Additionally, Tc was found to be an increasing function of bent-core concentration.
研究論文（学術雑誌）
DOI：https://doi.org/10.1080/02678290412331293378
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DOI ID：10.1080/02678290412331293378, ISSN：0267-8292, SCOPUS ID：4944222731 - Achromatic coronagraph based on out-of-plane common-path nulling interferometer
Alexander V. Tavrov; Yosuke Tanaka; Tatsutoshi Shioda; Takashi Kurokawa; Mitsuo Takeda
Proceedings of SPIE - The International Society for Optical Engineering, 巻：5491, 号：PART 2, 開始ページ：824, 終了ページ：830, 2004年
3D common-path interferometer is proposed to obtain achromatic nulling for star coronagraphy. Common-path scheme compensates optical path difference (OPD) effectively and is stable to mechanical vibrations. 3D ray geometry involves polarization rotations ±90° in each interferometer arm and results in achromatic 180° phase shift for destructive interference for on-axial source. The interferometer throughput is obtained at nearly 100% for entire polarized light and nearly 50/50 ratio of light energy is split between Bright and Nulled ports for off-axial source. Theory, simulations and preliminary breadboard experiments are shown in reasonable agreement.
研究論文（国際会議プロシーディングス）
DOI：https://doi.org/10.1117/12.550759
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DOI ID：10.1117/12.550759, ISSN：0277-786X, SCOPUS ID：11144283710 - Step-wise Fréedericksz transition in a nematic liquid crystal
Tatsutoshi Shioda; Bing Wen; Charles Rosenblatt
Journal of Applied Physics, 巻：94, 号：12, 開始ページ：7502, 終了ページ：7504, 2003年12月
A step-wise Fre′edericksz transition in a nematic liquid crystal was studied. It was shown that the intensity-voltage profile above the Fre′edericksz threshold voltage may exhibit a shoulder by controlling the anchoring strength on a pixel-by-pixel basis. The two glass substrates coated with a semitransparent layer of electrically conducting indium-tin oxide were cleaned consecutively in detergent, water, acetone and ethanol. It was found that at highest temperature, δT=0.8°C, the intensity-voltage curve exhibits a profile typical for a Fre′edericksz transition in which both substrates were characterized by a spatially uniform anchoring strength coefficient.
研究論文（学術雑誌）
DOI：https://doi.org/10.1063/1.1629389
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DOI ID：10.1063/1.1629389, ISSN：0021-8979, SCOPUS ID：0346935283 - Experimental determination of molecular polarizability anisotropy of nematogens by depolarized Rayleigh light scattering
Kazuhiro Yokota; Tatsutoshi Shioda; Michi Nakata; Yoichi Takanishi; Ken Ishikawa; Hideo Takezoe; Masamitsu Ishitobi; Chizu Sekine
Liquid Crystals, 巻：30, 号：6, 開始ページ：697, 終了ページ：700, 2003年06月
The anisotropy of molecular polarizability Δα of several nematogens has been determined by depolarized Rayleigh light scattering. The experimentally determined values were found to be noticeably smaller than those obtained by MOPAC calculation. Δα values determined from order parameter S and refractive indices show reasonably good agreement with those determined in the present experiment. This result warns us that Δα calculated by MOPAC, particularly at a finite wavelength, may be larger than the true value.
研究論文（学術雑誌）
DOI：https://doi.org/10.1080/02678290310000
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DOI ID：10.1080/02678290310000, ISSN：0267-8292, SCOPUS ID：0037982426 - Continuous nematic anchoring transition due to surface-induced smectic order
Tatsutoshi Shioda; Bing Wen; Charles Rosenblatt
Physical Review E - Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, 巻：67, 号：4, 開始ページ：5, 終了ページ：417065, 2003年
A continuous transition from tilted to homeotropic alignment at an interface is observed at a temperature [Formula presented] for a nematic liquid crystal on cooling toward the nematic–smectic-[Formula presented] phase transition temperature. [Formula presented] is found to depend on the treatment of the substrate. The behavior is examined theoretically in terms of a pair of competing easy axes (homeotropic and planar) and the tilt elasticity associated with the growth of surface-induced smectic order. © 2003 The American Physical Society.
研究論文（学術雑誌）
DOI：https://doi.org/10.1103/PhysRevE.67.041706
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DOI ID：10.1103/PhysRevE.67.041706, ISSN：1063-651X, SCOPUS ID：85037255944 - Liquid crystals align liquid crystals
Tatsutoshi Shioda; Yoshinori Okada; Doo Han Chung; Yoichi Takanishi; Ken Ishikawa; Byoungchoo Park; Hideo Takezoe
Japanese Journal of Applied Physics, Part 2: Letters, 巻：41, 号：3 A, 2002年03月
We have investigated the molecular orientation of a liquid crystal (LC), pentylcyanobiphenyl (5CB), evaporated on a rubbed polymer by means of polarized ultraviolet absorption spectroscopy and surface second-harmonic generation. The results unambiguously reveal that the in-plane anisotropy is diminishingly small before the molecules form a monolayer, although films thicker than one monolayer have a finite in-plane anisotropy. This drastic change indicates that LC molecules on rubbed surfaces do not align well without the influence of the intermolecular interaction of LCs. Actually we confirmed that nonliquid-crystalline butylcyanobipheny (4CB) exhibits no orientation on the rubbed polymer surface regardless of thickness.
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/jjap.41.l266
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DOI ID：10.1143/jjap.41.l266, ISSN：0021-4922, SCOPUS ID：0036508652 - Axial and polar orientational changes by rubbing/photoalignment processes in a liquid crystal alignment layer studied by optical second-harmonic generation
T. Shioda; D. H. Chung; Y. Takanishi; K. Ishikawa; B. Park; H. Takezoe
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, 巻：40, 号：4 A, 開始ページ：2387, 終了ページ：2390, 2001年04月
Molecular reorientation by rubbing and photoalignment processes in polymer alignment layer for liquid crystals has been studied by linear optical absorption and surface optical second-harmonic generation. It was found that rubbing produces polar and axial orders in the photoisomerizable polyamic acid (PAA) containing azobenzene groups in the main chain, while photoalignment after rubbing destroys the polar order but is capable of reorienting the PAA main chain without creating further polar order.
研究論文（学術雑誌）
DOI：https://doi.org/10.1143/jjap.40.2387
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DOI ID：10.1143/jjap.40.2387, ISSN：0021-4922, SCOPUS ID：0035301997 - Polarization characteristics from SFG spectra of clean and regulatively oxidized Ni(100) surfaces adsorbed by propionate and formate
Tetsuo Yuzawa; Tatsutoshi Shioda; Jun Kubota; Ken Onda; Akihide Wada; Kazunari Domen; Chiaki Hirose
Surface Science, 巻：416, 号：1-2, 1998年10月
Experiments have been carried out on propionate and formate adsorbed on clean and regulatively oxidized Ni(100) surfaces to scrutinize the notion that the polarization characteristics of infrared-visible sum frequency generation (SFG) signals of molecules on metallic surfaces are different from those due to molecules on insulating surfaces. Both propionate and formate give signals only for p-polarized visible pulses on clean metal and oxygen-saturated surfaces, but signals due to s-polarized visible pulses appeared from the propionate-covered surface as soon as the surface was covered with a monolayer of NiO(100). Vibrational peaks of propionate were located at 2887, 2945, and 2988 cm-1 and were assigned to the symmetric stretching mode of CH2 group, the symmetric stretching mode of CH3 group, and the degenerate stretching mode of CH3 group, respectively. The peak of the surface formate was located at 2948 cm-1 on the clean metal surface, but another band appeared at 2860 cm-1 on oxide-layered surfaces. The causes of the appearance of the (sp) polarization signals by the presence of the NiO layer are discussed. © 1998 Elsevier Science B.V. All rights reserved.
研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0039-6028(98)00625-6
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DOI ID：10.1016/S0039-6028(98)00625-6, ISSN：0039-6028, SCOPUS ID：0032180929
- Axial zoomable 2D single-shot comb interferometry using spatial phase modulator for profilometry and tomography
Tuan Cong Truong; Tuan Quoc Banh; Heuihyeon Kim; Tatsutoshi Shioda
巻：439, 開始ページ：276, 終了ページ：283, 2019年05月15日
© 2019 Elsevier B.V. We propose 2D single-shot comb interferometry with the capability of zooming along the axial axis for profilometry and tomography. A spatial phase modulator (SPM) based a diffraction grating is utilized to realize the zooming operation with a fine scale in the proposed system. The measurable range of the fine scale can be varied from 200μm to 1.2 mm by controlling the diffraction orders of the SPM, allowing a magnification tool for surface profilometry. An optical-frequency comb-interferometry-based Fabry–Perot etalon is used to extend the measurement range of proposed system with a coarse scale up to 10.8 mm. In both the coarse and fine scales, the tomography resolution is maintained at approximately 2.5μm.
英語
DOI：https://doi.org/10.1016/j.optcom.2019.01.029
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DOI ID：10.1016/j.optcom.2019.01.029, ISSN：0030-4018, J-Global ID：201902291511816685, SCOPUS ID：85061210770 - Generation of broadband frequency-variable laser comb allowing full-frequency sweep in the near-infrared region
Takashi Kurokawa; Tatsutoshi Shioda; Motohiro Koriba; Mitsutaka Ito; Ken Kashiwagi; Takuma Serizawa; Yosuke Tanaka
巻：438, 開始ページ：13, 終了ページ：17, 2019年05月01日
© 2019 Elsevier B.V. We succeeded in developing a broadband-frequency-variable laser comb with a mode spacing of 12.5 GHz in the near-infrared region. We found that the spectrum of optical pump pulses can be frequency shifted over the mode spacing frequency by a single-sideband (SSB) optical modulator involving the amplitude and phase. Optical heterodyne measurement showed that the frequency shift of the optical pump pulses was precisely consistent with the modulation frequency applied to the SSB modulator with an accuracy of 20 kHz. The pump pulses were amplified and compressed to enhance the peak intensity. Finally, the frequency-shifted pump pulses launched into highly nonlinear fibers and generated a frequency-shifted laser comb. The precise frequency shift of pump pulses induced a simultaneous frequency shift of all modes of the laser comb. As a result, we succeeded in fast frequency sweeping of the laser comb over a full spectral range of 1080 to 1750 nm. This full-wavelength tuning implies that laser light of arbitrary and accurate wavelength can be obtained over the comb bandwidth.
英語
DOI：https://doi.org/10.1016/j.optcom.2018.12.086
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DOI ID：10.1016/j.optcom.2018.12.086, ISSN：0030-4018, J-Global ID：201902280722758379, SCOPUS ID：85059912698 - Development of discrete frequency swept laser for 2D single‐shot pseudo comb interferometry
TRUONG Tuan Cong; TRUONG Tuan Cong; BANH Tuan Quoc; BANH Tuan Quoc; SHIODA Tatsutoshi
Japanese Journal of Applied Physics, 巻：58, 号：5, 開始ページ：056503.1‐056503.6, 2019年
© 2019 The Japan Society of Applied Physics. We propose a discrete frequency swept laser with sufficient sweep repetition rate (SRR) of 10 kHz order for 2D single-shot pseudo comb interferometry, in which the shutter speed of 2D imaging sensor is operated at 10 μs order. The proposed light source can overcome the limited SRR in 1 kHz order of the conventional discrete frequency swept lasers, which are not adequate for 2D single-shot pseudo comb interferometry. The proposed light source with a frequency step of approximately 200 GHz and an SRR of 29 kHz is demonstrated, showing an effectiveness for the axial range expansion of 2D single-shot industrial profilometry and tomography in several tens of millimeters.
英語
DOI：https://doi.org/10.7567/1347-4065/ab0a7f
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DOI ID：10.7567/1347-4065/ab0a7f, ISSN：0021-4922, eISSN：1347-4065, J-Global ID：201902222711799113, SCOPUS ID：85067796557 - Scan‐less dual‐heterodyne mixing for dispersion spectrum measurement
SULTANA Nasrin; YUDA Leona; SHIODA Tatsutoshi
Optics & Photonics Japan講演予稿集(CD-ROM), 巻：2018, 開始ページ：ROMBUNNO.1pB9, 2018年10月24日
英語
J-Global ID：201902292378243261 - Controlling the dynamic range of 2D single‐shot imaging by frequency step of the discrete semiconductor tunable laser
TRUONG Tuan Cong; BANH Tuan Quoc; BANH Tuan Quoc; SHIODA Tatsutoshi
Optics & Photonics Japan講演予稿集(CD-ROM), 巻：2017, 開始ページ：ROMBUNNO.2aB2, 2017年10月16日
英語
J-Global ID：201702276984036707 - Precise profilometry for scattered media and tomography for multiple‐layers samples using the Discrete frequency scanning laser
TRUONG Tuan Cong; BANH Tuan Quoc; BANH Tuan Quoc; SHIODA Tatsutoshi
応用物理学会春季学術講演会講演予稿集(CD-ROM), 巻：64th, 開始ページ：ROMBUNNO.17a‐418‐8, 2017年03月01日
英語
J-Global ID：201702283349397655 - Controlling frequency step of discrete frequency scanning laser by means of etalon thickness
TRUONG Tuan Cong; BANH Tuan Quoc; BANH Tuan Quoc; KIM Heuihyeon; SHIODA Tatsutoshi
Optics & Photonics Japan講演予稿集(CD-ROM), 巻：2016, 開始ページ：ROMBUNNO.2aD8, 2016年10月15日
英語
J-Global ID：201602250686217131 - Development of discrete frequency scanning laser for interferometry
TRUONG Cong Tuan; BANH Quoc Tuan; BANH Quoc Tuan; KIM Heui Hyeon; SHIODA Tatsutoshi
応用物理学会秋季学術講演会講演予稿集(CD-ROM), 巻：77th, 開始ページ：ROMBUNNO.15p‐C32‐6, 2016年09月01日
英語
J-Global ID：201602266875783459 - Fiber optic remote sensor based on laser powering and liquid-crystal-based optical modulator
Yosuke Tanaka; Sayuri Sugano; Muneyuki Nakagawa; Tatsutoshi Shioda; Takashi Kurokawa; Toshiharu Fukuoka; Kazuyuki Ueta
巻：5855 PART II, 開始ページ：992, 終了ページ：995, 2005年
This paper demonstrates a novel fiber optic remote sensing system based on laser powering and a liquid-crystal optical modulator that transforms electrical signal of sensors into optical with low power consumption. A basic experiment for confirming the principle was conducted using a standard communication-grade semiconductor laser with the output of less than 20 mW both for laser powering and for sensor signal transmission. The sensor signal was transferred through 5-km-long optical fiber and detected with On/Off ratio of more than 15 dB.
DOI：https://doi.org/10.1117/12.623792
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DOI ID：10.1117/12.623792, ISSN：0277-786X, SCOPUS ID：28544453115
- 光領域差動利得信号生成技術の開拓と半透明サンプルの高速低雑音計測への応用
日本学術振興会, 科学研究費助成事業 挑戦的研究(萌芽), 挑戦的研究(萌芽), 2022年06月30日 - 2024年03月31日
田中 洋介; 塩田 達俊, 東京農工大学
配分額（総額）：6500000, 配分額（直接経費）：5000000, 配分額（間接経費）：1500000
課題番号：22K18790 - 電力線の絶縁破壊兆候を早期発見する高感度光ファイバセンシングの国際共同研究
日本学術振興会, 科学研究費助成事業, 国際共同研究加速基金(国際共同研究強化(B)), 2021年10月07日 - 2024年03月31日
田中 洋介; 稲田 優貴; 塩田 達俊, 東京農工大学
配分額（総額）：17680000, 配分額（直接経費）：13600000, 配分額（間接経費）：4080000
本研究の目的は、分布型光ファイバセンサによる温度または振動測定を利用した電力線の絶縁劣化初期段階の観測について、その具体的な手法を実際の電力施設を用いて確立することにある。そのためにマレーシアの電力会社テナガ・ナショナルの研究所(TNBR)内で、現地で実際に使用されているものと同等の電力線を用意し、センシング用の光ファイバを敷設することを計画した。分布型光ファイバセンシングについては、日本、マレーシア両国の研究者が協力して事前に準備実験を行うこととした。研究の第一段階の目標は、送電状態を変化させ、分布型光ファイバセンサで測定される電力線長手方向の温度分布や振動分布の変化との関係を明らかにすることとした。2021年度は、コロナ禍のため現地での実験を進めることができなくなったが、オンラインでの議論を活発に行い、両国の研究者が協力して光ファイバ分布センシングの高空間分解能化や高速化のための様々な手法の提案と原理確認を進めた。具体的には、光ファイバ内の散乱現象の一つであるブリュアン散乱が温度や歪みによって波長を変化させる現象を利用したセンシングにおいて、波長変化自体を測る従来手法に代わり、散乱光のパワーから即座に温度や歪みの変化を測定する手法を考案し、原理実証を行った。また、光源に光周波数コム光源を用いてブリュアン散乱を発生させ、散乱光スペクトルを一括測定する新たな手法の提案を行った。更に、精度向上のために機械学習を利用した手法について手掛けた。
課題番号：21KK0067 - 周波数領域光相関によるワンショット/広範囲/超高分解光波形計測法の研究
日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2021年04月01日 - 2024年03月31日
塩田 達俊, 埼玉大学
配分額（総額）：17550000, 配分額（直接経費）：13500000, 配分額（間接経費）：4050000
本研究の目的は、フェムト秒やピコ秒の時間分解能での光波形を“ワンショット”で計測する光計測システムを開発することである。具体的には、申請者が初めて提案した“周波数領域の”光相関測定を高速波形計測に適用し、100 fs台から1 nsまで時間的にギャップのないワンショット光波形計測システムを実現することである。初年度は、テラヘルツ領域に到達する兆候繰返し光パルス列をプローブ用光源として発生することを目標に実験し、100fs台の繰返し光パルスを生成した。さらに光単側波帯変調器を組み込んだ光ループ回路によりCW光を光源とした場合に100周回オーダーでの光周回を確認した。
課題番号：21H01837 - 二光子吸収応答受光系を用いた多点光ファイバ型ベクトル曲げセンサ
日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2020年04月01日 - 2023年03月31日
田中 洋介; 塩田 達俊, 東京農工大学
配分額（総額）：17810000, 配分額（直接経費）：13700000, 配分額（間接経費）：4110000
本研究の目標は、一本の光ファイバに複数の光路をまとめたマルチコア光ファイバをセンシングヘッドとして用い、このファイバを取り付けた対象に加わる曲げの大きさ、および向きを同時に多点で計測可能なセンサを実現することである。一本の光ファイバで多点の曲げ計測ができるようになれば、大型構造物の状態診断、ロボットアームの曲げセンシング、医療用カテーテルの曲げ監視等、様々な分野に応用できる。光ファイバは電磁雑音の影響を受けないため、このセンサは電磁波が飛び交う製造現場や電力施設、医療におけるMRI検査の現場等、様々な環境下で使用できる。また、軽量、細径で柔軟なことから、設置対象への影響が無視できる。
提案する曲げ計測システムは、光ファイバ回折格子をマルチコア光ファイバに加工したものをセンシングヘッドとすると共に、光信号を受光素子の二光子吸収応答を利用して処理する点に特徴がある。2021年度は、このシステムで測定の高速化を実現するため、光信号の波長掃引と強度変調の新たな制御手法の検討を進め、今後の発展のための土台を築いた。また、前年度までに行った多点3次元曲げ計測の研究成果を踏まえ、光ファイバ型の形状計測システムへの応用を実証した。光ファイバで効率よく計測できる形状は、なだらかな曲線形状のものが中心であり、当初想定した構造物診断や医療機器の曲げ計測応用に適している。今回、センシングファイバを医療用カテーテルに組み込み、曲げ形状計測への応用について実証実験を行った。マルチコア光ファイバでは複数の隣接する光路で温度の影響が同じであるため、ひずみ測定における誤差要因となる温度の影響をキャンセルし、温度無依存測定が可能なことを併せて実証した。
課題番号：20H02158 - フェムト秒時間分解－離散時間分散光コムシングルショット過渡吸収分光法の研究
日本学術振興会, 科学研究費助成事業, 挑戦的研究(萌芽), 2017年06月30日 - 2020年03月31日
塩田 達俊, 埼玉大学
配分額（総額）：6500000, 配分額（直接経費）：5000000, 配分額（間接経費）：1500000
シングルショット位相計測を、200 GHzの光周波数コムのモード間の25GHzサンプリングにより、40ピコ秒の時間領域で行う光システムの研究を行ってきた。この技術を過渡応答計測に適用する場合、時間分解能と広域な時間窓の両立には、広帯域かつ高分解な位相スペクトルの計測・制御技術が求められる。本課題で時間並列計測方式を考案し、1台の位相検波回路によって位相スペクトル計測を可能とした。375GHz (25GHz 、15modes)における振幅・位相スペクトルを測定し、2.7ps分解能、40ps時間レンジの超高速光電界波形計測が可能であることを実験的に示した。
課題番号：17K19069 - 光コム光源の導入による高速かつ高精度な分布型ファイバセンシング
日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2016年04月01日 - 2019年03月31日
田中 洋介; 塩田 達俊, 東京農工大学
配分額（総額）：16770000, 配分額（直接経費）：12900000, 配分額（間接経費）：3870000
本研究では、光周波数コムと呼ばれる周波数間隔一定の多波長光を用いた高速かつ高精度なファイバセンシングの実現を目標として検討を開始した。この手法はブリュアン利得スペクトルが光源の周波数掃引なしで測定できるため、短時間測定が可能である。利得スペクトルの一括測定に加え、光周波数コムによる多モード誘導ブリュアン散乱を用いたセンシングのでは、従来手法に対し最大で3桁の感度拡大が可能な測定系を実現した。また、本研究を進める中で関連するファイバセンシング技術として、光ファイバ回折格子を多点設置した高精度測定を着想し、実験による検証に成功した。
課題番号：16H04374 - 高速離散波長可変レーザーと擬似光周波数コム干渉顕微鏡の研究
日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2016年04月01日 - 2019年03月31日
塩田 達俊, 埼玉大学
配分額（総額）：16900000, 配分額（直接経費）：13000000, 配分額（間接経費）：3900000
モノづくり現場における製品の表面形状の検査装置に用いる技術の研究を行った。光学干渉計を用いた非接触計測により、深さ方向にマイクロメートル分解能でミリメートル領域の距離計測が可能な2次元シングルショット計測器を構築した。簡易に発生できる光コムを光源として、高次までの疑似光コム干渉で得られるシングルショット2次元断層像を体積サンプリング速度の高速なCCDで観測した。一方、その光源としてCCDの撮像時間より早い超高速な光周波数走査繰返し（1MHz）と離散的に周波数走査（200GHz間隔）する高速離散波長可変レーザーを新たに開発して疑似光コム干渉の基礎技術を開発した。
課題番号：16H03879 - フェムト秒時間分解光コムシングルショット過渡吸収分光法の研究
日本学術振興会, 科学研究費助成事業, 挑戦的萌芽研究, 2015年04月01日 - 2017年03月31日
塩田 達俊, 埼玉大学
配分額（総額）：4030000, 配分額（直接経費）：3100000, 配分額（間接経費）：930000
フェムト秒の時間分解能で数10ピコ秒の計測時間をもつシングルショット任意光波形制御/計測技術の実現をするために，これまでに我々は光周波数コムシンセサイザ/アナライザを開発した．ここで、時間分解能と制御時間領域の比と，その計測制御時間での積算時間を改善するために前者に対しては200 GHzコムのピーク間を25 GHzでサンプリングすることで計測時間を5ピコ秒から40ピコ秒へ拡大することを目指す．また，後者に対しては40ピコ秒の時間窓で信号光を切り出して1 GHzデジタイザでシングルショット計測することで，疑似的な25 GHz(40 ps)デジタイザでのシングルショット計測を実証した．
課題番号：15K13372 - 周波数可変な広帯域マルチギガヘルツコムによる分光計測法の研究
日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2014年04月01日 - 2017年03月31日
黒川 隆志; 塩田 達俊; 田中 洋介, 東京農工大学
配分額（総額）：16120000, 配分額（直接経費）：12400000, 配分額（間接経費）：3720000
本研究の目的は，広モード間隔の広帯域コムの全てのモードを一括して周波数シフトできる周波数可変なコム光源を開発することにある．この周波数可変コム光源を用いて，広帯域性と高分解能を併せ持つ分光技術を開拓する．
パルス整形で生成した4 psの短光パルス(繰り返し12.5GHz）を単側波帯変調器によりMHz精度で周波数シフトできることを確認した．このパルスを圧縮・増幅したのち高非線形ファイバに入射して，1100-1700 nmに及ぶ広帯域かつ周波数可変なコムを生成することに成功した．このコム光を回折格子分光器に入射し，低圧ガスやファプリペローフィルタのスペクトルを1 MHzの分解能で得ることに成功した．
課題番号：26286057 - 高強度マルチギガヘルツコムを用いた広ダイナミックレンジ分光・形状計測
日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2013年04月01日 - 2016年03月31日
柏木 謙; 黒川 隆志; 田中 洋介; 塩田 達俊, 東京農工大学
配分額（総額）：18460000, 配分額（直接経費）：14200000, 配分額（間接経費）：4260000
本研究課題では周波数間隔の広い光周波数コムを用いて広ダイナミックレンジの計測法を開発した。光周波数コムはある一定の間隔で周波数成分を持つ光源であり、一般的な周波数間隔の狭い光周波数コムは光強度が多くの周波数成分に分散するため各周波数成分の強度が低い。周波数間隔が10 GHz以上と広い光周波数コム(マルチギガヘルツコム)は少ない周波数成分に光強度が集中するため各成分の強度が高い。これにより広いダイナミックレンジが期待できる。本研究課題ではこのようなコムを計測に利用するため、広帯域マルチギガヘルツコムの周波数可変化技術を開発し、そのようなコムを用いた計測応用を検討した。
課題番号：25286065 - シングルショット-フェムト秒時間分解光周波数コムアナライザの研究
日本学術振興会, 科学研究費助成事業, 挑戦的萌芽研究, 2013年04月01日 - 2015年03月31日
塩田 達俊, 埼玉大学
配分額（総額）：3900000, 配分額（直接経費）：3000000, 配分額（間接経費）：900000
既存の計測手法に頼らず、非対称な超高速波形を高感度に計測できるフーリエ空間の多波長電界ヘテロダイン検波法と呼ばれる手法を開発した。光コムの隣接ピーク間の相対位相を、参照光コムを用いて検出する。フーリエ空間光源システムの試作・動作を下記項目に沿って行った。
1. 25GHz光周波数コム(256波)をシード光とした200GHz光周波数コム(32波)を生成した。
2. 光コムのパルス列をスペクトル領域つまり光コムの電界スペクトルをデジタイザにより波形時間内に測定することに成功した。測定した光電界スペクトルを逆フーリエ変換することで繰返し時間内で時間波形を測定して再現することに成功した。
課題番号：25600114 - 超高速ホログラフィック光周波数コム合成法の研究
日本学術振興会, 科学研究費助成事業, 若手研究(A), 2011年04月01日 - 2014年03月31日
塩田 達俊
配分額（総額）：27430000, 配分額（直接経費）：21100000, 配分額（間接経費）：6330000
フェムト秒時間分解能で光波形の制御と計測を実現するために、新たな光信号処理と計測技術を考案した。ピーク間隔100ギガヘルツ以上の光周波数コムを生成し、そのピーク毎の振幅・位相を制御できる光回路を構築した。また、複数のピーク間の位相スペクトルを測定できる二波長同時ヘテロダイン検波法を考案した。これらの制御系と計測系を融合すると、フェムト秒時間領域での任意光波形を周波数領域で制御することが可能になる。これをフェムト秒光周波数コム合成・解析法とし、光周波数コムの振幅・位相スペクトルの制御を行い、フェムト秒からピコ秒領域の超高速任意光波形の発生と計測に成功した。
課題番号：23686014 - 光周波数コムを利用した周波数＆時間分解近接場磁気光学顕微鏡の研究開発
日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2011年04月01日 - 2014年03月31日
石橋 隆幸; 塩田 達俊, 長岡技術科学大学
配分額（総額）：17680000, 配分額（直接経費）：13600000, 配分額（間接経費）：4080000
ナノ領域での磁気特性を評価するため、アパーチャーレスプローブを用いたSNOMの構築と、偏光特性の調査をおこなった。その結果、約10 nmの空間分解能と良好な偏光特性を実現するとともに、アパーチャーレスSNOMにおいて問題であった背景光と信号光の分離に成功した。FDTDシミュレーションでは、実験で得られた偏光特性をほぼ正確に再現することに成功し、プローブ周辺の電場分布を理解することができた。さらに、時間分解測定を実現するための装置の構築を行った。
課題番号：23310073 - プロジェクション方式とレンチキュラ方式のハイブリット型立体表示に関する研究
日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2008年 - 2010年
高木 康博; 塩田 達俊, 東京農工大学
配分額（総額）：18720000, 配分額（直接経費）：14400000, 配分額（間接経費）：4320000
眼精疲労のない人に優しい自然な立体ディスプレイを実現するためには、非常に多くの画像を同時に表示する必要がある。本研究では、レンチキュラ方式とマルチプロジェクション方式の構成方法を組み合わせた新しい立体ディスプレイの構成方法としてハイブリッド型の構成方法を提案した。ハイブリッド型の構成方法を用いて、256枚の画像を表示する立体ディスプレイシステムを試作した。試作システムに対する人間の眼の調節応答を測定し、眼精疲労のない奥行き表示範囲が拡大することを確かめた。
課題番号：20360153 - 光周波数コム光源を用いた3次元顕微鏡の分解能向上と計測の高速化
日本学術振興会, 科学研究費助成事業, 若手研究(B), 2008年 - 2009年
塩田 達俊
配分額（総額）：4420000, 配分額（直接経費）：3400000, 配分額（間接経費）：1020000
非線形ファイバを含み光パルスシンセサイザによる任意波形生成システムを光源とする3次元形状計測の実験系を組み、効率よく広帯域なスーパーコンティニューム光が得られる条件を確定した。3nm程度であった種光源のスペクトル帯域は、上記システムにより80nm程度まで拡大することがわかった。このとき、分解能は35micronとなった。
課題番号：20760031 - 光変調器を用いた光周波数掃引による高分解能分光システム
日本学術振興会, 科学研究費助成事業, 若手研究(B), 2006年 - 2007年
塩田 達俊
配分額（総額）：3600000, 配分額（直接経費）：3600000
高分解能な分光システムは基礎科学から応用まで幅広いニーズがある。これまで分解能1MHz、計測範囲100GHzと高性能なシステムが実現されているが、光周波数標準や物理化学過程の追跡などの進展のためにさらに性能の向上が望まれてきた。申請者は課題実施までに単側波(SSB)光変調器を用いて光周波数を高精度に且つプログラマブルに制御してスペクトル計測システムの実現を図ってきた。本研究課題では、SSB光変調器スペクトル計測システムの分解能を向上し、これまでの周波数制御システムをベースにして、新たに周波数安定化した光源を導入してシステムの性能を発展させることを目的とした。
平成19年度は、前年度までに構築した高分解スペクトル計測システムの計測範囲の広帯域化をはかった。また、光変調器を用いたシステム全体を構築して計測精度の確認を行った。具体的には5THz以上の周波数帯域を示す光周波数コムを光源として光フィルタにより個々のピークを切り出し、光変調器による高精度な光周波数掃引を行う実験系を構築した。光ファイバとインライン半透鏡を組み合せて構築した1MHz線幅の共振器の透過スペクトルを計測することで、実測値として1MHzの分解能を確認した。さらに、H^<13>C^<14>Nガス(圧力約1Tprr、長さ約80cm)を用いた繰り返し計測から1MHz以下の光周波数計測精度を得た。また、光フィルタの掃引による光周波数コムのピークを選択することで1THz以上の計測帯域を得ることを確認した。
課題番号：18760038 - 時空間多重表示を用いた自然な三次元ディスプレイの研究
日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2006年 - 2007年
高木 康博; 塩田 達俊, 東京農工大学
配分額（総額）：17050000, 配分額（直接経費）：14800000, 配分額（間接経費）：2250000
1.時間多重表示モジュールの実現
高密度指向性表示を行う時間多重表示モジュールを提案した。これは、ひとつの表示モジュールで複数の指向性画像を異なる水平方向へ表示する。高フレームレート表示デバイスを変形二次元配置した光源アレイで照明し、指向性確保のために結像系に光源アレイと相似な配列の開口アレイを配置する。
高フレームレート表示デバイスにはDMDを用い、光源アレイには白色LEDアレイを用いた。指向性画像間のクロストークと結像系の収差の評価から、多重度を15に決定した。実際に時間多重表示モジュールを設計・試作した。DMDをフレームレート900Hzで駆動し、60Hzのフレームレートで15個の指向性画像の表示を実現した。
2.時間多重光学エンジンの実現
複数台の時間多重表示モジュールを変形2次元配置して空間的に多重化することで、多数の指向性画像を表示する時間多重光学エンジンを実現した。すべてのモジュールは、モジュールの開口アレイの開口部が水平方向に連続になるように、水平位置が一致しないように縦横に変形二次元配置する。
時間多重表示モジュールを4台試作し、これらを変形2次元配置して、60指向性表示を行う時間多重光学エンジンを実現した。
3.時間多重高密度指向性ディスプレイの実現
時間多重光学エンジンに共有レンズと垂直方向拡散板を組み合わせて、多重結像系を構成し、時間多重高密度指向性ディスプレイを実現した。
共有レンズとして組み合わせフレネルレンズを用い、垂直方向拡散板としてレンチキュラシートを用いた。異なる水平方向へ0.31°ピッチで60方向への画像表示を実現した。
4.制御システム
1台のPCで4台のモジュールの制御を実現した。プロジェクション型画像表示システムでは、収差による画像歪みが生じるので、表示画像を逆に歪ませて表示することで、画像歪み補正を行った。すべての指向性画像に対して画像歪みを測定し、歪み補正テーブルを用意した。
課題番号：18360165 - RF制御による光周波数コムを利用した3次元顕微鏡の研究
日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2006年 - 2007年
黒川 隆志; 塩田 達俊; 武田 光夫, 東京農工大学
配分額（総額）：16610000, 配分額（直接経費）：14900000, 配分額（間接経費）：1710000
(1)コム発生系の広帯域化と深さ分解能の改善
コム発生器の後段に試作した等価フィルタと光増幅器を設置し、コムのスペクトル帯域が約3倍広帯域化した。これを光源として光干渉計へ適用した結果、適用前に100μmだった深さ分解能は、40μm以下に改善された。次に、非共振器型周波数コム発生器とパルスシンセサイザによりジッターとチャープの少ない種パルスを生成し、これを高非線形分散シフトファイバに導入して、コム間隔の可変化と広帯域化が可能なスーパーコンティニュウム光発生を言った。2kmのときにはピークパワー5.5Wのときに今回の最大帯域幅60nmまで拡大された。また200MHzの掃引コム間隔周波数が可能であった。これにより、深さ分解能は、30μmまで改善された。
(2)空間光学干渉計の設計と構築
1次元イメージセンサを用いた空間光学干渉計の設計と製作を行った。シリドリンカルレンズと対物レンズを導入することにより、顕微鏡干渉光学系を構成した。横(水平)方向空間分解能は8μmとなり、光コヒーレンストモグラフィへ応用できることを確認した。
(3)3次元顕微鏡の基本動作の確認
コム間隔周波数の掃引、イメージセンサの制御とデータ取得を一括してコンピュータ制御する系を構築して、3次元顕微鏡の基本動作を確認した。コム間隔周波数は25GHzを中心に10MHz掃引することで、約1mmの深さを観察することができた。3次元画像の取得時間約1分の性能を確認した。基本的な3次元画像として10円玉表面の凹凸形状を計測して"十"文字を深さ分解能40μm以下、水平方向分解能8μm程度で鮮明な画像が得られることを示した。また、ガラス膜の膜厚測定も精度数ミクロンでおこなえることを確認し、トモグラフィへの応用も可能なことを確認した。
課題番号：18360164 - 周波数コムを用いた光コヒーレンス・トモグラフィの研究
日本学術振興会, 科学研究費助成事業, 基盤研究(B), 2004年 - 2005年
黒川 隆志; 田中 洋介; 塩田 達俊; 武田 光夫, 東京農工大学
配分額（総額）：15300000, 配分額（直接経費）：15300000
従来の光による形状計測では、広帯域光源を用いた低コヒーレンス干渉や波長可変レーザを用いた波長走査法やコヒーレンス関数合成法のように時間平均として仮想的な周波数コム合成法も試みられている。しかし、これらは周波数間隔とコム発生法に制限が多く、ファイバセンシングのような距離計測に対しての応用に限られている。本研究では光周波数コムの周波数帯域を広帯域化して、周波数間隔数十GHzの光コムを用いた新しい表面形状法を提案し、本方式を適用して段差計測または膜厚計測を行った。
平成16年度は光周波数コムの発生方法として、波長1550nmのレーザー光を直列につながれた2個の位相変調器に入射することで12 GHz間隔で、帯域500 GHzの周波数コムを発生した。この時、片方の位相変調器に逓倍器によって2倍波の変調信号を入力することでより広い帯域の周波数コムが得られた。この手法により0.1mmから10mに及ぶ範囲で任意の深さの表面形状を物理的な稼動部を必要せずに計測することができる。実験によって計測精度300μmが得られた。
平成17年度はさらに高分解能な計測を実現するために,コムのピーク間隔を2倍に広げた上に共振器内に位相変調器を設置して光周波数コムの帯域を広げる方法を用いた。その結果,帯域は約10 THzとなり前年度の約20倍の帯域が得られた。ここで共振器の周波数特性を利用すると約30MHzから40MHzの範囲を掃引できることがわかった。この光源を実験に応用500μmの膜厚のガラス板を試料として繰返し計測を行った。その結果,帯域は約10 THzとなり計測の精度を19.7μmとすることに成功した。
課題番号：16360027