Details of the Researcher

PHOTO

Toshihiko Hirooka
Section
Research Institute of Electrical Communication
Job title
Professor
Degree

  • 博士（工学）（大阪大学）

  • 修士（工学）（大阪大学）

Professional Memberships 3

  • IEEE

  • Optical Society of America

  • 電子情報通信学会

Research Interests 3

  • 非線形ファイバ光学

  • 光信号処理

  • 超高速光伝送

Research Areas 1

  • Informatics / Information networks /

Papers 262

  1. Coherent Nyquist optical pulse transmission at nearly 1-Tb/s/λ over 1,600 km with a capacity of 21.5 Tb/s using PS-32 QAM signals

    Shohei Beppu, Aoto Ishikawa, Takeki Serikawa, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    Optics Express　32　(9)　16533-16533　2024/04/19

    Publisher: Optica Publishing Group

    DOI： 10.1364/oe.518396 　

    eISSN： 1094-4087

    More details Close

    We demonstrate the 1,600-km transmission at nearly 1-Tb/s/λ signals with a capacity of 21.5 Tb/s. Probabilistic shaping was newly applied to high-speed coherent optical Nyquist pulse transmission systems to maximize the transmission capacity. Employing a 160-GBd PS-32 QAM format, WDM signals at nearly 1-Tb/s/λ were successfully transmitted over 1,600 km with a capacity of 21.5 Tb/s.

  2. Eigen-function division multiplexed coherent optical transmission in time domain by using higher-order Hermite-Gaussian pulses

    Masataka Nakazawa, Masato Yoshida, Toshihiko Hirooka

    Optics Express　32　(7)　12682-12682　2024/03/21

    Publisher: Optica Publishing Group

    DOI： 10.1364/oe.510189 　

    eISSN： 1094-4087

    More details Close

    We describe a new multiplexing technique and its application to demultiplexing in the time domain by using higher-order Hermite-Gaussian (HG) pulses, which are solutions of the Schrödinger equation. We call this technique eigen-function division multiplexing (EDM). This method enables us to further increase the total transmission capacity by superimposing many different HG pulses in the same time slot. This technique is different from a conventional optical time domain multiplexing (OTDM) technique using interleaving, where one pulse exists only in one time slot. The transmitted EDM HG pulses can be demultiplexed by adopting the time-domain orthogonality of the HG pulses (eigen-function orthogonality). The information carried by the mth-order HG pulse (HGm pulse) can be coherently detected by a photo detector, where photo-mixing with a phase-locked HGm pulse generated by a local oscillator can realize demultiplexing. The overlap integral with a different HG pulse becomes zero due to the time domain orthogonality. First, we show numerically that such a new EDM transmission scheme in the time domain is possible. We then show experimentally that we could successfully carry out an EDM HG coherent pulse transmission with four different HG pulses (HG0, HG1, HG2, and HG3), where we report a 400∼480 Gbit/s (10 Gbaud x 4 eigen-functions x 2 pol-mux.) 32∼64 QAM EDM transmission over 300∼450 km.

  3. Experiments on the Generation of Higher-Order Hermite-Gaussian Pulses From an FM Mode-Locked Laser

    Masataka Nakazawa, Masato Yoshida, Toshihiko Hirooka

    IEEE Journal of Quantum Electronics　59　(6)　1-16　2023/12

    Publisher: Institute of Electrical and Electronics Engineers (IEEE)

    DOI： 10.1109/jqe.2023.3305121 　

    ISSN： 0018-9197

    eISSN： 1558-1713

  4. Demodulation Performance Comparison of High-Speed Coherent Nyquist Pulse Signal with Analog and Digital Demultiplexing Schemes

    Masato YOSHIDA, Kosuke KIMURA, Toshihiko HIROOKA, Keisuke KASAI, Masataka NAKAZAWA

    IEICE Transactions on Communications　E106.B　(11)　1059-1064　2023/11/01

    Publisher: Institute of Electrical and Electronics Engineers (IEEE)

    DOI： 10.1587/transcom.2022obp0001 　

    ISSN： 0916-8516

    eISSN： 1745-1345

  5. GAWBS Noise in Digital Coherent Transmission

    Masataka Nakazawa, Masato Yoshida, Toshihiko Hirooka

    Journal of Lightwave Technology　41　(11)　3358-3371　2023/06/01

    Publisher: Institute of Electrical and Electronics Engineers (IEEE)

    DOI： 10.1109/jlt.2023.3255942 　

    ISSN： 0733-8724

    eISSN： 1558-2213

  6. Experiments on Generation of Various Dark and Bright Pulses From an FM Mode-Locked Laser

    Masataka Nakazawa, Masato Yoshida, Toshihiko Hirooka

    IEEE Journal of Quantum Electronics　58　(6)　1-23　2022/12

    Publisher: Institute of Electrical and Electronics Engineers (IEEE)

    DOI： 10.1109/jqe.2022.3210339 　

    ISSN： 0018-9197

    eISSN： 1558-1713

  7. Experimental and Numerical Analysis of Ultrahigh-Speed Coherent Nyquist Pulse Transmission with Low-Nonlinearity Dispersion Compensator

    Kosuke KIMURA, Masato YOSHIDA, Keisuke KASAI, Toshihiko HIROOKA, Masataka NAKAZAWA

    IEICE Transactions on Communications　E105.B　(9)　1014-1022　2022/09/01

    Publisher: Institute of Electronics, Information and Communications Engineers (IEICE)

    DOI： 10.1587/transcom.2021ebp3178 　

    ISSN： 0916-8516

    eISSN： 1745-1345

  8. Demodulation Performance Comparison of 160 Gbaud Coherent Nyquist Pulse Signal with Analog and Digital DEMUX Schemes

    Masato Yoshida, Kosuke Kimura, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    2022 27th OptoElectronics and Communications Conference (OECC) and 2022 International Conference on Photonics in Switching and Computing (PSC)　2022/07/03

    Publisher: IEEE

    DOI： 10.23919/oecc/psc53152.2022.9849876 　

  9. 10.2 Tbit/s (1.28 Tbit/s/ch x 8 ch) WDM Nyquist Pulse Transmission over 2100 km

    Aoi Watanabe, Aoto Ishikawa, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    2022 27th OptoElectronics and Communications Conference (OECC) and 2022 International Conference on Photonics in Switching and Computing (PSC)　2022/07/03

    Publisher: IEEE

    DOI： 10.23919/oecc/psc53152.2022.9849931 　

  10. Software-Defined Fiber Optic Communications for Ultrahigh-Speed Optical Pulse Transmission Systems

    Mahdi Naghshvarianjahromi, Shiva Kumar, M. Jamal Deen, Taro Iwaya, Kosuke Kimura, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    IEEE Journal of Selected Topics in Quantum Electronics　28　(4)　1-10　2022/07

    Publisher: Institute of Electrical and Electronics Engineers (IEEE)

    DOI： 10.1109/jstqe.2022.3190885 　

    ISSN： 1077-260X

    eISSN： 1558-4542

  11. Experiments on an AM Mode-Locked Laser as an Arbitrary Optical Function Generator

    Masataka Nakazawa, Masato Yoshida, Toshihiko Hirooka

    IEEE JOURNAL OF QUANTUM ELECTRONICS　58　(3)　2022/06

    DOI： 10.1109/JQE.2022.3165322 　

    ISSN： 0018-9197

    eISSN： 1558-1713

  12. Experiments on an FM Mode-Locked Laser as an Arbitrary Optical Function Generator

    Masataka Nakazawa, Masato Yoshida, Toshihiko Hirooka

    IEEE JOURNAL OF QUANTUM ELECTRONICS　58　(3)　2022/06

    DOI： 10.1109/JQE.2022.3165317 　

    ISSN： 0018-9197

    eISSN： 1558-1713

  13. Broadband injection-locked homodyne receiver for digital coherent transmission using a low Q Fabry-Perot LD

    Keisuke Kasai, Takashi Kan, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　30　(8)　13345-13355　2022/04

    DOI： 10.1364/OE.456327 　

    ISSN： 1094-4087

  14. Precise Measurements and their Analysis of GAWBS-Induced Depolarization Noise in Multi-Core Fiber for Digital Coherent Transmission

    Masato Yoshida, Kozo Sato, Toshihiko Hirooka, Keisuke Kasai, Masataka Nakazawa

    IEICE TRANSACTIONS ON COMMUNICATIONS　E105B　(2)　151-158　2022/02

    DOI： 10.1587/transcom.2021CEP0006 　

    ISSN： 0916-8516

    eISSN： 1745-1345

  15. Measurement of Mode-Coupling Along a Multi-Core Submarine Fiber Cable with a Multi-Channel OTDR

    Masato Yoshida, Toshihiko Hirooka, Nakazawa Masataka, Tetsuya Hayashi, Takemi Hasegawa, Kohei Nakamura, Takanori Inoue

    2022 European Conference on Optical Communication, ECOC 2022　2022

  16. Theory of AM Mode-Locking of a Laser as an Arbitrary Optical Function Generator

    Masataka Nakazawa, Toshihiko Hirooka

    IEEE Journal of Quantum Electronics　57　(6)　2021/12/01

    Publisher: Institute of Electrical and Electronics Engineers Inc.

    DOI： 10.1109/JQE.2021.3114173 　

    ISSN： 1558-1713 0018-9197

  17. GAWBS noise correlation between cores in multi-core fibers

    Kozo Sato, Masato Yoshida, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　29　(26)　42523-42537　2021/12

    DOI： 10.1364/OE.442261 　

    ISSN： 1094-4087

  18. A generalized mode-locking theory for a Nyquist laser with an arbitrary roll-off factor Part I: Master equations and optical filters in a Nyquist laser

    Masataka Nakazawa, Toshihiko Hirooka

    IEEE Journal of Quantum Electronics　57　(3)　2021/06/01

    Publisher: Institute of Electrical and Electronics Engineers Inc.

    DOI： 10.1109/JQE.2021.3065960 　

    ISSN： 1558-1713 0018-9197

  19. A Generalized Mode-Locking Theory for a Nyquist Laser with an Arbitrary Roll-Off Factor PART II: Oscillation Waveforms and Spectral Characteristics

    Masataka Nakazawa, Toshihiko Hirooka

    IEEE Journal of Quantum Electronics　57　(3)　2021/06/01

    Publisher: Institute of Electrical and Electronics Engineers Inc.

    DOI： 10.1109/JQE.2021.3065935 　

    ISSN： 1558-1713 0018-9197

  20. 10 Channel WDM 80 Gbit/s/ch, 256 QAM Bi-Directional Coherent Transmission for a High Capacity Next-Generation Mobile Fronthaul

    Masato Yoshida, Takashi Kan, Keisuke Kasai, Toshihiko Hirooka, Katsumi Iwatsuki, Masataka Nakazawa

    JOURNAL OF LIGHTWAVE TECHNOLOGY　39　(5)　1289-1295　2021/03

    DOI： 10.1109/JLT.2020.3034417 　

    ISSN： 0733-8724

    eISSN： 1558-2213

  21. Ultrahigh-Speed Nyquist Pulse Transmission Beyond 10 Tbit/s

    Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS　27　(2)　2021/03

    DOI： 10.1109/JSTQE.2020.3011939 　

    ISSN： 1077-260X

    eISSN： 1558-4542

  22. Chromatic dispersion dependence of GAWBS phase noise compensation with pilot tone

    Kozo Sato, Takashi Kan, Masato Yoshida, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　29　(7)　10676-10687　2021/03

    DOI： 10.1364/OE.418891 　

    ISSN： 1094-4087

  23. 10 Tbit/s QAM Quantum Noise Stream Cipher Coherent Transmission Over 160 Km

    Masato Yoshida, Takashi Kan, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    JOURNAL OF LIGHTWAVE TECHNOLOGY　39　(4)　1056-1063　2021/02

    DOI： 10.1109/JLT.2020.3016693 　

    ISSN： 0733-8724

    eISSN： 1558-2213

  24. Experimental demonstration of distortion mitigation in 15 Tbit/s OTDM transmission using a cognitive dynamic system

    Mahdi Naghshvarianjahromi, Shiva Kumar, Jamal Deen, Taro Iwaya, Kosuke Kimura, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    26th Optoelectronics and Communications Conference　2021

    Publisher: OSA

    DOI： 10.1364/oecc.2021.t4b.8 　

  25. Single-Channel 1.28 Tbit/s Optical Nyquist Pulse Transmission over 3000 km with Roll-off Factor Optimization

    Aoi Watanabe, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    26th Optoelectronics and Communications Conference　2021

    Publisher: OSA

    DOI： 10.1364/oecc.2021.t4b.6 　

  26. Broadband Dynamic Injection-Locking Performance of Fabry-Perot LD and Its Application to Coherent Homodyne Receiver

    Takashi Kan, Keisuke Kasai, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    2021 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXPOSITION (OFC)　2021

  27. 64 Gbit/s, 256 QAM Transmission Through Coherent Optical-Wireless Link at 61 GHz Using Simple and High OSNR Carrier Frequency Converter

    Keisuke Kasai, Taisei Sato, Toshihiko Hirooka, Masato Yoshida, Masataka Nakazawa

    2021 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXPOSITION (OFC)　2021

  28. GAWBS Noise Correlation Between Cores in Four-Core Fiber

    Kozo Sato, Masato Yoshida, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    2021 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXPOSITION (OFC)　2021

  29. Spectrally efficient pilot tone-based compensation of inter-channel cross-phase modulation noise in a WDM coherent transmission using injection locking

    Takashi Kan, Kozo Sato, Masato Yoshida, Toshihiko Hirooka, Keisuke Kasai, Masataka Nakazawa

    OPTICS EXPRESS　29　(2)　1454-1469　2021/01

    DOI： 10.1364/OE.414381 　

    ISSN： 1094-4087

  30. Injection-locked 256 QAM WDM coherent transmissions in the C- and L-bands

    Takashi Kan, Keisuke Kasai, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　28　(23)　34665-34676　2020/11

    DOI： 10.1364/OE.404786 　

    ISSN： 1094-4087

  31. Precise measurements and their analysis of GAWBS-induced depolarization noise in various optical fibers for digital coherent transmission

    Masato Yoshida, Naoya Takefushi, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　28　(23)　34422-34433　2020/11

    DOI： 10.1364/OE.409326 　

    ISSN： 1094-4087

  32. Digital Coherent Optical Access Technologies for beyond 5G Network

    Keisuke Kasai, Masataka Nakazawa, Masato Yoshida, Katsumi Iwatsuki, Toshihiko Hirooka

    2020 IEEE International Symposium on Radio-Frequency Integration Technology, RFIT 2020　145-147　2020/09/01

    Publisher: Institute of Electrical and Electronics Engineers Inc.

    DOI： 10.1109/RFIT49453.2020.9226206 　

  33. GAWBS phase noise characteristics in multi-core fibers for digital coherent transmission

    Naoya Takefushi, Masato Yoshida, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　28　(15)　23012-23022　2020/07

    DOI： 10.1364/OE.399202 　

    ISSN： 1094-4087

  34. Theoretical and experimental analyses of GAWBS phase noise in various optical fibers for digital coherent transmission

    Naoya Takefushi, Masato Yoshida, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　28　(3)　2873-2883　2020/02

    DOI： 10.1364/OE.384505 　

    ISSN： 1094-4087

  35. 64 Gbit/s, 256 QAM Coherently-Linked Optical and Wireless Transmission in 61 GHz Band Using Novel Injection-Locked Carrier Frequency Converter.

    Keisuke Kasai, Toshihiko Hirooka, Masato Yoshida, Masataka Nakazawa

    1-3　2020

    DOI： 10.1109/ECOC48923.2020.9333340 　

  36. Low-Nonlinearity, Dispersion-Compensated Transmission Line with a Chirped Fiber Bragg Grating and Its Application to Ultrahigh-Speed Coherent Nyquist Pulse Transmission

    Taro Iwaya, Kosuke Kimura, Masato Yoshida, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    2020 OPTO-ELECTRONICS AND COMMUNICATIONS CONFERENCE (OECC 2020)　2020

    ISSN： 2166-8884

    eISSN： 2166-8892

  37. Precise and Wideband Compensation of Inter-Channel Cross-Phase Modulation Noise in WDM Coherent Transmission Using Injection Locking

    Takashi Kan, Kozo Sato, Masato Yoshida, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    2020 OPTO-ELECTRONICS AND COMMUNICATIONS CONFERENCE (OECC 2020)　2020

    ISSN： 2166-8884

    eISSN： 2166-8892

  38. Chromatic Dispersion Dependence of GAWBS Noise

    Kozo Sato, Takashi Kan, Masato Yoshida, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    2020 OPTO-ELECTRONICS AND COMMUNICATIONS CONFERENCE (OECC 2020)　2020

    ISSN： 2166-8884

    eISSN： 2166-8892

  39. Wavelength-tunable sub-picosecond optical switch over entire C-band using nonlinear optical loop mirror Peer-reviewed

    R. Hirata, T. Hirooka, M. Yoshida, M. Nakazawa

    IEICE Electron. Express　16　(23)　20190664　2019/12

  40. Suppression of large error floor in 1024 QAM digital coherent transmission by compensating for GAWBS phase noise Peer-reviewed

    M. Yoshida, N. Takefushi, K. Kasai, T. Hirooka, M. Nakazawa

    Opt. Express　27　(25)　36691-36698　2019/12

    DOI： 10.1364/OE.27.036691 　

    ISSN： 1094-4087

  41. Experimental and theoretical analyses of GAWBS depolarization noise in digital coherent transmission Peer-reviewed

    N. Takefushi, M. Yoshida, T. Hirooka, K. Kasai, M. Nakazawa

    European Conference on Optical Communication (ECOC 2019)　Tu.1.C.1　2019/09

  42. Demonstration of on-line bi-directional 10-RRHs with an 80 Gbit/s/RRH capacity using 256 QAM WDM coherent transmission for next generation mobile fronthaul Peer-reviewed

    T. Kan, M. Yoshida, K. Kasai, T. Hirooka, K. Iwatsuki, M. Nakazawa

    European Conference on Optical Communication (ECOC 2019)　M.1.C.4　2019/09

  43. Single-channel 15.3 Tbit/s, 64 QAM coherent Nyquist pulse transmission over 150 km with a spectral efficiency of 8.3 bit/s/Hz Peer-reviewed

    M. Yoshida, K. Kimura, T. Iwaya, K. Kasai, T. Hirooka, M. Nakazawa

    Opt. Express　27　(20)　28952-28967　2019/09

    DOI： 10.1364/OE.27.028952 　

    ISSN： 1094-4087

  44. Sub-Picosecond Optical Switch over Entire C-band by Using Nonlinear Optical Loop Mirror Peer-reviewed

    R. Hirata, T. Hirooka, M. Yoshida, M. Nakazawa

    Opto-Electronics and Communications Conference (OECC 2019)　Th1C-5　2019/07

  45. GAWBS Noise Characteristics in Digital Coherent Transmission in Various Optical Fibers Peer-reviewed

    N. Takefushi, M. Yoshida, K. Kasai, T. Hirooka, M. Nakazawa

    Opto-Electronics and Communications Conference (OECC 2019)　Th2C-5　2019/07

  46. Real-Time 256 QAM Bi-directional Coherent Transmission in Next Generation Mobile Fronthaul Peer-reviewed

    M. Yoshida, T. Kan, K. Kasai, T. Hirooka, M. Nakazawa

    Opto-Electronics and Communications Conference (OECC 2019)　TuA2-3　2019/07

  47. Dual-polarization on-line 256 and 512 QAM digital coherent transmission Peer-reviewed

    M. Yoshida, K. Kasai, T. Hirooka, M. Nakazawa

    Optical Fiber Communication Conference (OFC 2019)　M2H.4　2019/03

  48. Single-channel 10.2 Tbit/s (2.56 Tbaud) optical Nyquist pulse transmission over 300 km Peer-reviewed

    T. Hirooka, R. Hirata, J. Wang, M. Yoshida, M. Nakazawa

    Opt. Express　26　(21)　27221-27236　2018/10

    DOI： 10.1364/OE.26.027221 　

    ISSN： 1094-4087

  49. Single-channel 10.2 Tbit/s PDM-DQPSK Nyquist pulse transmission over 300 km Peer-reviewed

    T. Hirooka, R. Hirata, J. Wang, M. Yoshida, M. Nakazawa

    European Conference on Optical Communication (ECOC 2018)　We3G.6　2018/09

  50. Backward-Rayleigh-Scattering Suppressed 160 Gbit/s 256 QAM Injection-Locked Bidirectional Coherent Transmission for Next Generation Mobile Fronthaul Peer-reviewed

    K. Kasai, M. Yoshida, T. Hirooka, K. Iwatsuki, M. Nakazawa

    European Conference on Optical Communication (ECOC 2018)　Th2.71　2018/09

  51. Single-Channel 7.68 Tbit/s, 64 QAM Coherent Nyquist Pulse Transmission over 150 km with a Spectral Efficiency of 9.7 bit/s/Hz Peer-reviewed

    K. Kimura, J. Nitta, M. Yoshida, K. Kasai, T. Hirooka, M. Nakazawa

    Opto-Electronics and Communications Conference (OECC 2018)　5B3-4　2018/07

  52. 50.4 Tbit/s, 128 QAM L-band WDM Injection Locked Coherent Transmission over 160 km with Spectral Efficiency of 10.5 bit/s/Hz Peer-reviewed

    T. Kan, K. Kasai, M. Yosida, T. Hirooka, M. Nakazawa

    Opto-Electronics and Communications Conference (OECC 2018)　5B3-3　2018/07

  53. Reverse Phase Modulation Technique for GAWBS Noise Error Floor Elimination in 1024 QAM-160 km Digital Coherent Transmission Peer-reviewed

    M. Yoshida, N. Takefushi, M. Terayama, K. Kasai, T. Hirooka, M. Nakazawa

    Opto-Electronics and Communications Conference (OECC 2018)　4B1-3　2018/07

  54. Single-channel 7.68 Tbit/s, 64 QAM coherent Nyquist pulse transmission over 150 km with a spectral efficiency of 9.7 bit/s/Hz Peer-reviewed

    Kosuke Kimura, Junpei Nitta, Masato Yoshida, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    Optics Express　26　(13)　17418-17428　2018/06/25

    Publisher: OSA - The Optical Society

    DOI： 10.1364/OE.26.017418 　

    ISSN： 1094-4087

  55. A New Optical Phase-Locked System between Ultrashort Pulses for 640 Gbaud Nyquist OTDM Coherent QAM Transmission Peer-reviewed

    Kosuke Kimura, Junpei Nitta, Masato Yoshida, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    European Conference on Optical Communication, ECOC　2017-　1-3　2018/04/24

    Publisher: Institute of Electrical and Electronics Engineers Inc.

    DOI： 10.1109/ECOC.2017.8345851 　

  56. 80 Gbit/s/ch, 256 QAM Digital Coherent Optical Transmission System with Injection-Locking for Next Generation Mobile Fronthaul Network Peer-reviewed

    Keisuke Kasai, Yixin Wang, Masato Yoshida, Toshihiko Hirooka, Katsumi Iwatsuki, Masataka Nakazawa

    European Conference on Optical Communication, ECOC　2017-　1-3　2018/04/24

    Publisher: Institute of Electrical and Electronics Engineers Inc.

    DOI： 10.1109/ECOC.2017.8346036 　

  57. Single-carrier 552 Gbit/s, 46 Gbaud 64 QAM Coherent Transmission over 100 km with Co-propagating 10 Gbit/s-OOK Signals Through a Deployed ROADM Network Peer-reviewed

    Keisuke Kasai, Toshihiko Hirooka, Masato Yoshida, Masataka Nakazawa, Masaki Shiraiwa, Yoshinari Awaji, Naoya Wada

    European Conference on Optical Communication, ECOC　2017-　1-3　2018/04/24

    Publisher: Institute of Electrical and Electronics Engineers Inc.

    DOI： 10.1109/ECOC.2017.8345944 　

  58. Observation of guided acoustic-wave Brillouin scattering noise and its compensation in digital coherent optical fiber transmission Peer-reviewed

    Masataka Nakazawa, Masato Yoshida, Masaki Terayama, Seiji Okamoto, Keisuke Kasai, Toshihiko Hirooka

    Optics Express　26　(7)　9165-9181　2018/04/02

    Publisher: OSA - The Optical Society

    DOI： 10.1364/OE.26.009165 　

    ISSN： 1094-4087

  59. Experimental and Numerical Comparison of Probabilistically-Shaped 4096 QAM and Uniformly-Shaped 1024 QAM in All-Raman Amplified 160 km Transmission Peer-reviewed

    S. Okamoto, M. Terayama, M. Yoshida, K. Kasai, T. Hirooka, M. Nakazawa

    Optical Fiber Communication Conference (OFC 2018)　M3C.5　2018/03

  60. Injection-locked Homodyne Detection for Higher-order QAM Transmission Invited Peer-reviewed

    K. Kasai, M. Yoshida, T. Hirooka, M. Nakazawa

    Optical Fiber Communication Conference (OFC 2018)　M4G.1　2018/03

  61. Observation of Guided Acoustic-Wave Brillouin Scattering and its Digital Compensation in Coherent QAM Transmission Peer-reviewed

    M. Nakazawa, M. Terayama, S. Okamoto, M. Yoshida, K. Kasai, T. Hirooka

    Optical Fiber Communication Conference (OFC 2018)　M4B.2　2018/03

  62. Experimental and numerical comparison of probabilistically shaped 4096 QAM and a uniformly shaped 1024 QAM in all-Raman amplified 160 km transmission Peer-reviewed

    Seiji Okamoto, Masaki Terayama, Masato Yoshida, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    Optics Express　26　(3)　3535-3543　2018/02/05

    Publisher: OSA - The Optical Society

    DOI： 10.1364/OE.26.003535 　

    ISSN： 1094-4087

  63. A 40 GHz, 770 fs regeneratively mode-locked erbium fiber laser operating at 1.6 μm Peer-reviewed

    K. Harako, M. Yoshida, T. Hirooka, M. Nakazawa

    IEICE Electron. Express　14　(18)　20170829　2017/10

  64. QAM Quantum Noise Stream Cipher Transmission over 100 km with Continuous Variable Quantum Key Distribution Peer-reviewed

    M. Nakazawa, M. Yoshida, T. Hirooka, K. Kasai, T. Hirano, T. Ichikawa, R. Namiki

    IEEE J. Quantum Electron　53　(4)　8000316　2017/08

  65. Low-loss and reflection-free fused type fan-out device for 7-core fiber based on a bundled structure Peer-reviewed

    Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　25　(16)　18817-18826　2017/08

    DOI： 10.1364/OE.25.018817 　

    ISSN： 1094-4087

  66. 1024 QAM Coherent Optical Transmission In 31 Km-long, 19-core Fiber With Low Crosstalk And Large Effective Area Peer-reviewed

    M. Yoshida, K. Kasai, T. Hirooka, M. Nakazawa, K. Imamura, R. Sugizaki

    Opto-Electronics and Communications Conference (OECC 2017)　3-1K-2　2017/08

  67. PMD issues in Nyquist transmission Invited Peer-reviewed

    T. Hirooka

    International Symposium on Ultrafast Photonic Technologies (ISUPT 2017)　Invited talk　2017/07

  68. Single-channel 3.84 Tbit/s, 64 QAM coherent Nyquist pulse transmission over 150 km with a spectral efficiency of 10.6 bit/s/Hz Peer-reviewed

    Junpei Nitta, Masato Yoshida, Kosuke Kimura, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　25　(13)　15199-15207　2017/06

    DOI： 10.1364/OE.25.015199 　

    ISSN： 1094-4087

  69. 40 GHz, 770 fs Harmonically and Regeneratively FM Mode-Locked Erbium Fiber Laser in L-Band Peer-reviewed

    K. Harako, M. Yoshida, T. Hirooka, M. Nakazawa

    Conference on Lasers and Electro-Optics (CLEO 2017)　SM4L.2　2017/05

  70. Subpicosecond Coherent Nyquist Pulse Generation for 1-Tbaud Transmission Using a C2H2 Frequency-Stabilized CW Laser and a 40 GHz Optical Comb Generator Peer-reviewed

    D. Suzuki, K. Kasai, T. Hirooka, M. Nakazawa

    Conference on Lasers and Electro-Optics (CLEO 2017)　SM2L.5　2017/05

  71. Fabrication of multi core fiber by using slurry casting method Peer-reviewed

    J. Yamamoto, T. Yajima, Y. Kinoshita, F. Ishii, M. Yoshida, T. Hirooka, M. Nakazawa

    Optical Fiber Communication Conference (OFC 2017)　Th1H.5　2017/03

  72. Single-channel 3.84 Tbit/s, 64 QAM coherent Nyquist pulse transmission over 150 km with frequency-stabilized and mode-locked laser Peer-reviewed

    M. Yoshida, J. Nitta, K. Kimura, K. Kasai, T. Hirooka, M. Nakazawa

    Optical Fiber Communication Conference (OFC 2017)　Th2A.52　2017/03

  73. New Optical Phase-Locking System Based on Mode-Locked Fiber Laser for 640 Gbaud Coherent Nyquist QAM Transmission

    Tohoku-Section Joint Convention Record of Institutes of Electrical and Information Engineers, Japan　2017　22-22　2017

    Publisher: Organizing Committee of Tohoku-Section Joint Convention of Institutes of Electrical and Information Engineers, Japan

    DOI： 10.11528/tsjc.2017.0_22 　

  74. Single-channel 5.12 Tbit/s (1.28 Tbaud) DQPSK transmission over 300 km using non-coherent Nyquist pulses Peer-reviewed

    D. Suzuki, K. Harako, T. Hirooka, M. Nakazawa

    Opt. Express　24　(26)　29682-29690　2016/12

  75. 440 fs, 9.2 GHz regeneratively mode-locked erbium fiber laser with a combination of higher-order solitons and a SESAM saturable absorber Peer-reviewed

    Toshihiko Hirooka, Kazunari Tokuhira, Masato Yoshida, Masataka Nakazawa

    OPTICS EXPRESS　24　(21)　24255-24264　2016/10

    DOI： 10.1364/OE.24.024255 　

    ISSN： 1094-4087

  76. Roll-off factor dependence of Nyquist pulse transmission Peer-reviewed

    Koudai Harako, Daiki Suzuki, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　24　(19)　21986-21994　2016/09

    DOI： 10.1364/OE.24.021986 　

    ISSN： 1094-4087

  77. Injection-locked Homodyne Detection System for Higher-order QAM Digital Coherent Transmission Invited Peer-reviewed

    K. Kasai, M. Yoshida, T. Hirooka, M. Nakazawa

    European Conference on Optical Communication (ECOC 2016)　M1.C.3　2016/09

  78. Single-channel 5.12 Tbit/s (1.28 Tbaud) DQPSK Transmission over 300 km Using Non-coherent Nyquist Pulses Peer-reviewed

    D. Suzuki, K. Harako, T. Hirooka, M. Nakazawa

    European Conference on Optical Communication (ECOC 2016)　W.4.P1.SC5.49　2016/09

  79. Real-time 70 Gbit/s, 128 QAM Quantum Noise Stream Cipher Transmission over 100 km with Secret Keys Delivered by Continuous Variable Quantum Key Distribution System Peer-reviewed

    M. Nakazawa, M. Yoshida, T. Hirooka, K. Kasai, T Hirano

    European Conference on Optical Communication (ECOC 2016)　W.4.P1.SC5.59　2016/09

  80. A Non-Perturbative Mode-Locking Theory of the Nyquist Laser With a Dirichlet Kernel Solution Peer-reviewed

    Masataka Nakazawa, Toshihiko Hirooka

    IEEE JOURNAL OF QUANTUM ELECTRONICS　52　(8)　1300113　2016/08

    DOI： 10.1109/JQE.2016.2584585 　

    ISSN： 0018-9197

    eISSN： 1558-1713

  81. A 1.55 mu m, 271 fs and 1.07 mu m, 294 fs simultaneously mode-locked Er- and Yb-doped fiber laser with a single SWNT/PVA saturable absorber Peer-reviewed

    Masatoshi Nakao, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    IEICE ELECTRONICS EXPRESS　13　(14)　20160515　2016/07

    DOI： 10.1587/elex.13.20160515 　

    ISSN： 1349-2543

  82. Roll-off factor dependence of system performance in 1.28 Tbit/s/ch-525 km Nyquist pulse transmission Peer-reviewed

    K. Harako, D. Suzuki, T. Hirooka, M. Nakazawa

    Opto-Electronics and Communications Conference (OECC 2016)　MB1-2　2016/07

  83. 1024 QAM, 7-core fiber/multi-core EDFA transmission over 100 km with an aggregated spectral efficiency of 109 bit/s/Hz Peer-reviewed

    M. Yoshida, K. Kasai, T. Hirooka, M. Nakazawa

    Opto-Electronics and Communications Conference (OECC 2016)　MB2-5　2016/07

  84. A mode locking theory of the Nyquist laser Peer-reviewed

    M. Nakazawa, T. Hirooka

    Conference on Lasers and Electro-Optics (CLEO 2016)　24　(5)　JTu5A.107-4995　2016/06

    DOI： 10.1364/OE.24.004981 　

  85. A 440 fs, 9.2 GHz hybrid mode-locked erbium fiber laser with a combination of higher-order solitons and a SESAM saturable absorber Peer-reviewed

    T. Hirooka, K. Tokuhira, M. Yoshida, M. Nakazawa

    Conference on Lasers and Electro-Optics (CLEO 2016)　STu1P.4　2016/06

  86. Fused type fan-out device for multi-core fiber based on bundled structure Peer-reviewed

    M. Yoshida, T. Hirooka, M. Nakazawa

    Optical Fiber Communication Conference (OFC2016)　Tu3I.2　2016/03

  87. Mode coupling measurement at a splice point between few-mode fibers using a synchronous multi-channel OTDR Peer-reviewed

    M. Yoshida, T. Hirooka, M. Nakazawa

    Optical Fiber Communication Conference (OFC2016)　Th1J.4　2016/03

  88. QAM quantum noise stream cipher using digital coherent optical transmission Invited Peer-reviewed

    M. Yoshida, T. Hirooka, K. Kasai, M. Nakazawa

    Conference Record - Asilomar Conference on Signals, Systems and Computers　2016-　1007-1011　2016/02/26

    Publisher: IEEE Computer Society

    DOI： 10.1109/ACSSC.2015.7421290 　

    ISSN： 1058-6393

  89. OH-free low loss single-mode fiber fabricated by slurry casting / rod-in-tube method Peer-reviewed

    T. Yajima, J. Yamamoto, Y. Kinoshita, F. Ishii, T. Hirooka, M. Yoshida, M. Nakazawa

    IEICE Electron. Express　13　(1)　20151005　2016/01

    DOI： 10.1587/elex.12.20151005 　

  90. Single-channel 40 Gbit/s digital coherent QAM quantum noise stream cipher transmission over 480 km Peer-reviewed

    Masato Yoshida, Toshihiko Hirooka, Keisuke Kasai, Masataka Nakazawa

    OPTICS EXPRESS　24　(1)　652-661　2016/01

    DOI： 10.1364/OE.24.000652 　

    ISSN： 1094-4087

  91. Single-Channel 1.92 Tbit/s, 64 QAM Coherent Nyquist Orthogonal TDM Transmission With a Spectral Efficiency of 10.6 Bit/s/Hz Peer-reviewed

    David Odeke Otuya, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    JOURNAL OF LIGHTWAVE TECHNOLOGY　34　(2)　768-775　2016/01

    DOI： 10.1109/JLT.2015.2468580 　

    ISSN： 0733-8724

    eISSN： 1558-2213

  92. Optical and wireless-integrated next-generation access network based on coherent technologies Invited Peer-reviewed

    Toshihiko Hirooka, Masato Yoshida, Keisuke Kasai, Masataka Nakazawa

    BROADBAND ACCESS COMMUNICATION TECHNOLOGIES X　9772　9772-2　2016

    DOI： 10.1117/12.2211860 　

    ISSN： 0277-786X

  93. First demonstration of digital coherent transmission in a deployed ROADM network with a 120 Gbit/s polarization-multiplexed 64 QAM signal Peer-reviewed

    Toshihiko Hirookaa, Keisuke Kasai, Yixin Wang, Masataka Nakazawa, Masaki Shiraiwa, Yoshinari Awaji, Naoya Wada

    IEICE ELECTRONICS EXPRESS　12　(23)　20150884　2015/12

    DOI： 10.1587/elex.12.20150884 　

    ISSN： 1349-2543

  94. Q-factor analysis of nonlinear impairments in ultrahigh-speed Nyquist pulse transmission Peer-reviewed

    Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　23　(26)　33484-33492　2015/12

    DOI： 10.1364/OE.23.033484 　

    ISSN： 1094-4087

  95. Real-time adaptive 4-64 QAM, 20-60 Gbit/s quantum noise stream cipher transmission over 320 km with FPGA-based transmitter and receiver Peer-reviewed

    Masato Yoshida, Toshihiko Hirooka, Keisuke Kasai, Masataka Nakazawa

    European Conference on Optical Communication, ECOC　2015-　P.5.13　2015/11/30

    Publisher: Institute of Electrical and Electronics Engineers Inc.

    DOI： 10.1109/ECOC.2015.7341787 　

  96. 2.56 Tbit/s/ch (640 Gbaud) polarization-multiplexed DQPSK non-coherent Nyquist pulse transmission over 525 km Peer-reviewed

    Koudai Harako, Daiki Seya, Daiki Suzuki, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　23　(24)　30801-30806　2015/11

    DOI： 10.1364/OE.23.030801 　

    ISSN： 1094-4087

  97. High-speed, high spectrally efficient 64 QAM orthogonal TDM coherent Nyquist pulse transmission Invited Peer-reviewed

    Keisuke Kasai, David Odeke Otuya, Koudai Harako, Toshihiko Hirooka, Masataka Nakazawa

    2015 IEEE Summer Topicals Meeting Series, SUM 2015　76-77　2015/09/09

    Publisher: Institute of Electrical and Electronics Engineers Inc.

    DOI： 10.1109/PHOSST.2015.7248201 　

  98. 1024 QAM, 7-core (60 Gbit/s x 7) fiber transmission over 55 km with an aggregate potential spectral efficiency of 109 bit/s/Hz Peer-reviewed

    Masato Yoshida, Shohei Beppu, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　23　(16)　20760-20766　2015/08

    DOI： 10.1364/OE.23.020760 　

    ISSN： 1094-4087

  99. Ultrafast Nyquist OTDM demultiplexing using optical Nyquist pulse sampling in an all-optical nonlinear switch Peer-reviewed

    Toshihiko Hirooka, Daiki Seya, Koudai Harako, Daiki Suzuki, Masataka Nakazawa

    OPTICS EXPRESS　23　(16)　20858-20866　2015/08

    DOI： 10.1364/OE.23.020858 　

    ISSN： 1094-4087

  100. Generation of optical Nyquist pulses and their applications to high speed/high spectral efficiency transmission Invited Peer-reviewed

    T. Hirooka

    International Symposium on Ultrafast Photonic Technologies/Extremely Advanced Transmission Technology (ISUPT/EXAT 2015)　M2.1　2015/07

  101. 2.56 Tbit/s/ch polarization-multiplexed DQPSK non-coherent Nyquist pulse transmission over 525 km Peer-reviewed

    D. Suzuki, D. Seya, K. Harako, T. Hirooka, M. Nakazawa

    International Symposium on Ultrafast Photonic Technologies/Extremely Advanced Transmission Technology (ISUPT/EXAT 2015)　P-35　2015/07

  102. Generation of 10 W, 100 fs, 10 GHz pulse train using high power EDFA-MOPA system with cascaded Raman pumping Peer-reviewed

    A. Fujisaki, M. Yoshida, T. Hirooka, M. Nakazawa

    Conference on Lasers and Electro-Optics (CLEO 2015)　STh1L.7　2015/05

  103. Ad-hoc photonic network based on movable and deployable ICT resource unit to meet rapidly changing service demands Peer-reviewed

    T. Sakano, T. Komukai, A. Takahara, T. Hirooka, M. Nakazawa

    Optical Fiber Communication Conference (OFC2015)　M2A.1　2015/03

  104. Single-channel 1.92 Tbit/s, 64 QAM coherent orthogonal TDM transmission of 160 Gbaud optical Nyquist pulses with 10.6 bit/s/Hz spectral efficiency Peer-reviewed

    D. O. Otuya, K. Harako, K. Kasai, T. Hirooka, M. Nakazawa

    Optical Fiber Communication Conference (OFC2015)　M3G.2　2015/03

  105. Real-time 10 Gbit/s-16 QAM quantum stream cipher transmission over 320 km with FPGA-based transmitter and receiver Peer-reviewed

    M. Yoshida, T. Hirooka, K. Kasai, M. Nakazawa

    Optical Fiber Communication Conference (OFC2015)　W4F.4　2015/03

  106. An 11.6 W output, 6 kHz linewidth, single-polarization EDFA-MOPA system with a (C2H2)-C-13 frequency stabilized fiber laser Peer-reviewed

    Akira Fujisaki, Shunichi Matsushita, Keisuke Kasai, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　23　(2)　1081-1087　2015/01

    DOI： 10.1364/OE.23.001081 　

    ISSN： 1094-4087

  107. High-performance TDM demultiplexing of coherent Nyquist pulses using time-domain orthogonality Peer-reviewed

    Koudai Harako, David Odeke Otuya, Keisuke Kasai, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　22　(24)　29456-29464　2014/12

    DOI： 10.1364/OE.22.029456 　

    ISSN： 1094-4087

  108. Measurement of mode coupling distribution along a few-mode fiber using a synchronous multi-channel OTDR Peer-reviewed

    Masataka Nakazawa, Masato Yoshida, Toshihiko Hirooka

    OPTICS EXPRESS　22　(25)　31299-31309　2014/12

    DOI： 10.1364/OE.22.031299 　

    ISSN： 1094-4087

  109. A Single-channel 40 Gbit/s Digital Coherent QAM Quantum Stream Cipher Transmission over 480 km Peer-reviewed

    M. Nakazawa, M. Yoshida, T. Hirooka

    Asia Communications and Photonics Conference (ACP2014)　ATh4E.1　2014/11

  110. Single-channel 1.92 Tbit/s, Pol-Mux-64 QAM coherent Nyquist pulse transmission over 150 km with a spectral efficiency of 7.5 bit/s/Hz Peer-reviewed

    David Odeke Otuya, Keisuke Kasai, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　22　(20)　23776-23785　2014/10

    DOI： 10.1364/OE.22.023776 　

    ISSN： 1094-4087

  111. OH-free, low loss single-mode fibre fabricated by slurry casting / rod-in-tube method Peer-reviewed

    T. Yajima, J. Yamamoto, Y. Kinoshita, F. Ishii, T. Hirooka, M. Yoshida, M. Nakazawa

    European Conference on Optical Communication (ECOC2014)　Th2.4.4　2014/09

    DOI： 10.1109/ECOC.2014.6963829 　

  112. Real-time adaptive 4-64 QAM coherent optical transmission over 320 km with FPGA-based transmitter and receiver Peer-reviewed

    M. Yoshida, T. Hirooka, K. Kasai, M. Nakazawa

    European Conference on Optical Communication (ECOC2014)　Th2.5.2　2014/09

    DOI： 10.1109/ECOC.2014.6963904 　

  113. Novel ultrafast TDM demultiplexing scheme using orthogonality in coherent Nyquist pulses Peer-reviewed

    K. Harako, D. O. Otuya, K. Kasai, T. Hirooka, M. Nakazawa

    European Conference on Optical Communication (ECOC2014)　Tu4.6.5　2014/09

    DOI： 10.1109/ECOC.2014.6963952 　

  114. A single-channel 960 Gbit/s 64 QAM orthogonal TDM transmission with a spectral efficiency of 10.0 bit/s/Hz using coherent Nyquist pulses Peer-reviewed

    D. O. Otuya, K. Harako, K. Kasai, T. Hirooka, M. Nakazawa

    European Conference on Optical Communication (ECOC2014)　We.2.3.4　2014/09

    DOI： 10.1109/ECOC.2014.6964004 　

  115. The Nyquist laser Peer-reviewed

    Masataka Nakazawa, Masato Yoshida, Toshihiko Hirooka

    OPTICA　1　(1)　15-22　2014/07

    DOI： 10.1364/OPTICA.1.000015 　

    ISSN： 2334-2536

  116. Plug-and-Play Optical Interconnection Using Digital Coherent Technology for Resilient Network Based on Movable and Deployable ICT Resource Unit Peer-reviewed

    Tetsuro Komukai, Hirokazu Kubota, Toshikazu Sakano, Toshihiko Hirooka, Masataka Nakazawa

    IEICE TRANSACTIONS ON COMMUNICATIONS　E97B　(7)　1334-1341　2014/07

    DOI： 10.1587/transcom.E97.B.1334 　

    ISSN： 1745-1345

  117. Q margin comparison of RZ and Nyquist optical pulses in ultrahigh-speed TDM transmission Peer-reviewed

    T. Hirooka, L. Chen, M. Nakazawa

    OECC 2014　MO2B-3　2014/07

  118. Adaptive 4~64 QAM real-time coherent optical transmission over 320 km with FPGA-based transmitter and receiver Peer-reviewed

    M. Yoshida, T. Hirooka, K. Kasai, M. Nakazawa

    Opt. Express　22　(13)　16520-16527　2014/06

    DOI： 10.1364/OE.22.016520 　

  119. A 160 mW output, 5 kHz linewidth frequency-stabilized erbium silica fiber laser with a short cavity configuration, Peer-reviewed

    K. Kasai, A. Fujisaki, M. Yoshida, T. Hirooka, M. Nakazawa, S. Masuda

    Conference on Lasers and Electro-Optics (CLEO 2014)　SW1N.4　2014/06

  120. 1.92 Tbit/s, 64 QAM coherent Nyquist pulse transmission over 150 km with a spectral efficiency of 7.5 bit/s/Hz Peer-reviewed

    D. O. Otuya, K. Kasai, T. Hirooka, M. Yoshida, M. Nakazawa

    OFC2014　W1A.4　2014/03

  121. 100 Gbit/s DP-QPSK transmission over a 32 km legacy multi-mode GI fiber using a real-time digital coherent transceiver Peer-reviewed

    T. Hirooka, M. Nakazawa, T. Komukai, T. Sakano

    OFC2014　W2A.1　2014/03

  122. Measurement of mode coupling distribution along a few-mode fiber using a synchronous multi-channel OTDR Peer-reviewed

    M. Nakazawa, M. Yoshida, T. Hirooka

    OFC2014　W3D.7　2014/03

  123. All-optical high-performance demultiplexing using optical Nyquist pulse sampling Peer-reviewed

    D. Seya, K. Harako, T. Hirooka, M. Nakazawa

    OFC2014　W4F.2　2014/03

  124. QAM quantum stream cipher using digital coherent optical transmission Peer-reviewed

    Masataka Nakazawa, Masato Yoshida, Toshihiko Hirooka, Keisuke Kasai

    OPTICS EXPRESS　22　(4)　4098-4107　2014/02

    DOI： 10.1364/OE.22.004098 　

    ISSN： 1094-4087

  125. A 160 mW output, 5 kHz linewidth frequency-stabilized erbium silica fiber laser with a short cavity configuration

    Keisuke Kasai, Akira Fujisaki, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa, Shin Masuda

    Optics InfoBase Conference Papers　2014

    Publisher: Optical Society of America (OSA)

    DOI： 10.1364/cleo_si.2014.sw1n.4 　

    ISSN： 2162-2701

  126. 100 Gbit/s real-time digital coherent transmission over a 32 km legacy multi-mode graded-index fiber Peer-reviewed

    Toshihiko Hirooka, Masataka Nakazawa, Tetsuro Komukai, Toshikazu Sakano

    IEICE ELECTRONICS EXPRESS　11　(15)　20140563　2014

    DOI： 10.1587/elex.11.20140563 　

    ISSN： 1349-2543

  127. Detailed comparison between mode couplings along multi-core fibers and structural irregularities using a synchronous multi-channel OTDR system with a high dynamic range Peer-reviewed

    Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa, Katsunori Imamura, Ryuichi Sugizaki, Takeshi Yagi

    Optics Express　21　(24)　29157-29164　2013/12/02

    Publisher: Optical Society of American (OSA)

    DOI： 10.1364/OE.21.029157 　

    ISSN： 1094-4087

  128. Low-loss photonic crystal fiber fabricated by a slurry casting method Peer-reviewed

    T. Yajima, J. Yamamoto, F. Ishii, T. Hirooka, M. Yoshida, M. Nakazawa

    Opt. Express　21　(25)　30500-30506　2013/12

    DOI： 10.1364/OE.21.030500 　

  129. A single-channel 1.28 Tbit/s-58 km transmission in the 1.1 mu m band with wideband GVD and slope compensation Peer-reviewed

    Kengo Koizumi, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　21　(23)　29055-29064　2013/11

    DOI： 10.1364/OE.21.029055 　

    ISSN： 1094-4087

  130. Nondestructive measurement of mode-coupling along a multi-core fiber using a synchronous multi-channel OTDR Invited Peer-reviewed

    M. Nakazawa, M. Yoshida, T. Hirooka

    International Symposium on Extremely Advanced Transmission Technology (EXAT 2013)　pp. 60-pp.63　2013/11

  131. 640 Gbaud (1.28 Tbit/s/ch) optical Nyquist pulse transmission over 525 km with substantial PMD tolerance Peer-reviewed

    K. Harako, D. Seya, T. Hirooka, M. Nakazawa

    Opt. Express　21　(18)　21063-21076　2013/09

    DOI： 10.1364/OE.21.021062 　

  132. A single-channel 1.92 Tbit/s, 64 QAM coherent optical pulse transmission over 150 km using frequency-domain equalization Peer-reviewed

    David Odeke Otuya, Keisuke Kasai, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　21　(19)　22808-22816　2013/09

    DOI： 10.1364/OE.21.022808 　

    ISSN： 1094-4087

  133. Resilient Photonic Network Architecture with Plug & play Optical Interconnection Technology Peer-reviewed

    T. Sakano, H. Kubota, T. Komukai, T. Hirooka, M. Nakazawa

    OECC2013　TuQ3-5　2013/07

  134. A Single-Channel 1.92 Tbit/s, 64 QAM Coherent Pulse OTDM Transmission over 150 km Peer-reviewed

    D. O. Otuya, K. Kasai, T. Hirooka, M. Yoshida, M. Nakazawa

    OECC2013　WR2-2　2013/07

  135. Marked Reduction of Depolarization-Induced Crosstalk in Ultrahigh-Speed Pol-MUX Transmission with an Optical Nyquist Pulse Peer-reviewed

    K. Harako, T. Hirooka, M. Nakazawa

    OECC2013　WR4-5　2013/07

  136. Measurement of Structural Irregularity Dependence on Mode Coupling along Multi-Core Fiber Using Multi-Channel OTDR System Peer-reviewed

    M. Yoshida, T. Hirooka, M. Nakazawa

    IEEE Summer Topicals 2013　MC3.3　2013/07

    DOI： 10.1109/PHOSST.2013.6614464 　

  137. Orthogonal TDM Using Optical Nyquist Pulses Invited Peer-reviewed

    T. Hirooka, M. Nakazawa

    Signal Processing in Photonic Communications (SPPCom 2013)　SPM1D.3　2013/07

  138. Generation of 9 W, 4 kHz linewidth 13C2H2 frequency-stabilized fiber laser output with core pumped erbium-doped amplifier Peer-reviewed

    A. Fujisaki, K. Kasai, M. Yoshida, T. Hirooka, M. Nakazawa

    Conference on Lasers and Electro-Optics (CLEO 2013)　CW3M.1　2013/06

  139. A Single-Channel, 1.6 Tbit/s 32 QAM Coherent Pulse Transmission Over 150 km With RZ-CW Conversion and FDE Techniques Peer-reviewed

    D. Otuya, K. Kasai, T. Hirooka, M. Yoshida, M. Nakazawa, T. Hara, S. Oikawa

    Optical Fiber Communication Conference (OFC2013)　OTh4E.4　2013/03

  140. Large PMD Tolerant 1.28 Tbit/s/ch Transmission over 525 km with 640 Gbaud Optical Nyquist Pulses Peer-reviewed

    K. Harako, P. Ruan, T. Hirooka, M. Nakazawa

    Optical Fiber Communication Conference (OFC2013)　JW2A.38　2013/03

  141. 160 Gbit/s-300 km single-channel transmission in the 1.1 mu m band with a precise GVD and slope compensation Peer-reviewed

    Kengo Koizumi, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　21　(4)　4303-4310　2013/02

    DOI： 10.1364/OE.21.004303 　

    ISSN： 1094-4087

  142. Second-order PMD-induced crosstalk between polarization-multiplexed signals and its impact on ultrashort optical pulse transmission Peer-reviewed

    Toshihiko Hirooka, Koudai Harako, Pengyu Guan, Masataka Nakazawa

    Journal of Lightwave Technology　31　(5)　809-814　2013

    DOI： 10.1109/JLT.2012.2236884 　

    ISSN： 0733-8724

  143. Dynamic optical transport connection with a 100 Gbit/s digital coherent optical transponder for disaster-resilient networking Peer-reviewed

    Toshihiko Hirooka, Masataka Nakazawa, Hirokazu Kubota, Tetsuro Komukai, Toshikazu Sakano

    2013 IEEE Region 10 Humanitarian Technology Conference, R10-HTC 2013　261-263　2013

    DOI： 10.1109/R10-HTC.2013.6669052 　

  144. 512 QAM transmission over 240 km using frequency-domain equalization in a digital coherent receiver Peer-reviewed

    Yuki Koizumi, Kazushi Toyoda, Tatsunori Omiya, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　20　(21)　23383-23389　2012/10

    DOI： 10.1364/OE.20.023383 　

    ISSN： 1094-4087

  145. A 31 mW, 280 fs passively mode-locked fiber soliton laser using a high heat-resistant SWNT/P3HT saturable absorber coated with siloxane Peer-reviewed

    Takato Ono, Yuichiro Hori, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa, Junji Mata, Jun Tsukamoto

    OPTICS EXPRESS　20　(21)　23659-23665　2012/10

    DOI： 10.1364/OE.20.023659 　

    ISSN： 1094-4087

  146. Marked performance improvement of 256 QAM transmission using a digital back-propagation method Peer-reviewed

    Kazushi Toyoda, Yuki Koizumi, Tatsunori Omiya, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　20　(18)　19815-19821　2012/08

    DOI： 10.1364/OE.20.019815 　

    ISSN： 1094-4087

  147. Linear and nonlinear propagation of optical Nyquist pulses in fibers Peer-reviewed

    Toshihiko Hirooka, Masataka Nakazawa

    OPTICS EXPRESS　20　(18)　19836-19849　2012/08

    DOI： 10.1364/OE.20.019836 　

    ISSN： 1094-4087

  148. Highly dispersion-tolerant 160 Gbaud optical Nyquist pulse TDM transmission over 525 km Peer-reviewed

    Toshihiko Hirooka, Peng Ruan, Pengyu Guan, Masataka Nakazawa

    OPTICS EXPRESS　20　(14)　15001-15007　2012/07

    DOI： 10.1364/OE.20.015001 　

    ISSN： 1094-4087

  149. Nondestructive measurement of mode couplings along a multi-core fiber using a synchronous multi-channel OTDR Peer-reviewed

    Masataka Nakazawa, Masato Yoshida, Toshihiko Hirooka

    OPTICS EXPRESS　20　(11)　12530-12540　2012/05

    DOI： 10.1364/OE.20.012530 　

    ISSN： 1094-4087

  150. Low Loss Photonic Crystal Fiber Fabricated by Slurry Casting Method Invited Peer-reviewed

    T. Yajima, J. Yamamoto, F. Ishii, T. Hirooka, M. Yoshida, M. Nakazawa

    Conference on Lasers and Electro-Optics (CLEO 2012)　CTh3G.1　2012/05

  151. Single-Carrier 800-Gb/s 32 RZ/QAM Coherent Transmission Over 225 km Employing a Novel RZ-CW Conversion Technique Peer-reviewed

    Keisuke Kasai, David Odeke Otuya, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    IEEE PHOTONICS TECHNOLOGY LETTERS　24　(5)　416-418　2012/03

    DOI： 10.1109/LPT.2011.2180373 　

    ISSN： 1041-1135

    eISSN： 1941-0174

  152. Measurement of Mode Couplings along a Multi-Core Fiber Using a Multi-Channel OTDR Peer-reviewed

    M. Nakazawa, M. Yoshida, T. Hirooka

    Optical Fiber Communication Conference (OFC2012)　OTh3I.3　2012/03

  153. Bandwidth and distance dependences of depolarization-induced crosstalk in polarization-multiplexed transmission Peer-reviewed

    T. Hirooka, K. Harako, P. Guan, M. Nakazawa

    Optical Fiber Communication Conference (OFC2012)　JW2A.44　2012/03

  154. 1.6 Tbit/s, Single-carrier 32 RZ/QAM Coherent Transmission Over 150 km Utilizing an RZ-CW Conversion Scheme

    Otuya David Odeke

    Tohoku-Section Joint Convention Record of Institutes of Electrical and Information Engineers, Japan　2012　12-12　2012

    Publisher: Organizing Committee of Tohoku-Section Joint Convention of Institutes of Electrical and Information Engineers, Japan

    DOI： 10.11528/tsjc.2012.0_12 　

  155. Ultrahigh-speed "orthogonal" TDM transmission with an optical Nyquist pulse train Peer-reviewed

    Masataka Nakazawa, Toshihiko Hirooka, Peng Ruan, Pengyu Guan

    OPTICS EXPRESS　20　(2)　1129-1140　2012/01

    DOI： 10.1364/OE.20.001129 　

    ISSN： 1094-4087

  156. Ultrafast Coherent Optical Transmission Invited Peer-reviewed

    Masataka Nakazawa, Toshihiko Hirooka, Masato Yoshida, Keisuke Kasai

    IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS　18　(1)　363-376　2012/01

    DOI： 10.1109/JSTQE.2011.2125781 　

    ISSN： 1077-260X

    eISSN： 1558-4542

  157. A 10 GHz 1.1 ps Regeneratively Mode-Locked Yb Fiber Laser in the 1.1 μm Band Peer-reviewed

    K. Koizumi, M. Yoshida, T. Hirooka, M. Nakazawa

    Opt. Express　19　(25)　25426-25432　2011/12

  158. 2.56 Tbit/s/ch Polarization-Multiplexed DQPSK Transmission over 300 km Using Time-Domain Optical Fourier Transformation Peer-reviewed

    P. Guan, T. Hirano, K. Harako, Y. Tomiyama, T. Hirooka, M. Nakazawa

    Opt. Express　19　(26)　B567-B573　2011/12

  159. Novel RZ-CW conversion scheme for ultra multi-level, high-speed coherent OTDM transmission Peer-reviewed

    M. Nakazawa, K. Kasai, M. Yoshida, T. Hirooka

    Opt. Express　19　(26)　B574-B580　2011/12

  160. PMD-Induced Crosstalk in Ultrahigh-Speed Polarization-Multiplexed Optical Transmission in the Presence of PDL Peer-reviewed

    Toshihiko Hirooka, Toshiyuki Hirano, Yutaro Tomiyama, Pengyu Guan, Masataka Nakazawa

    JOURNAL OF LIGHTWAVE TECHNOLOGY　29　(19)　2963-2970　2011/10

    DOI： 10.1109/JLT.2011.2163617 　

    ISSN： 0733-8724

  161. Comparison between polarization-multiplexed DPSK and single-polarization DQPSK in 640 Gbaud, 1.28 Tbit/s-500 km single-channel transmission Invited Peer-reviewed

    Yutaro Tomiyama, Koudai Harako, Pengyu Guan, Toshihiko Hirooka, Masataka Nakazawa

    OPTICAL FIBER TECHNOLOGY　17　(5)　439-444　2011/10

    DOI： 10.1016/j.yofte.2011.07.007 　

    ISSN： 1068-5200

  162. 10 GHz, 1.1 ps pulse generation from a harmonically and regeneratively mode-locked Yb fiber laser at 1.1 μm Peer-reviewed

    K. Koizumi, M. Yoshida, T. Hirooka, M. Nakazawa

    17th Microoptics Conference (MOC’11)　H-22　2011/10

  163. Novel RZ-CW Conversion Scheme for Ultra Multi-level, High-speed Coherent OTDM Transmission Peer-reviewed

    M. Nakazawa, K. Kasai, M. Yoshida, T. Hirooka

    European Conference on Optical Communication (ECOC2011)　We.10.P1.75　2011/09

  164. 2.56 Tbit/s/ch Polarization-mutliplexed DQPSK Transmission over 300 km Using Time-domain optical Fourier Transformation Peer-reviewed

    P. Guan, T. Hirano, K. Harako, Y. Tomiyama, T. Hirooka, M. Nakazawa

    European Conference on Optical Communication (ECOC2011)　We.10.P1.80　2011/09

  165. Recent Progress on Ultra-high Speed and Multi Level Coherent Transmission Invited Peer-reviewed

    T. Hirooka, K. Kasai, M. Nakazawa

    Korea-Japan Workshop on Beyond 100G　2011/06

  166. A 10 GHz 2.5 ps regeneratively mode-locked Yb fiber laser in the 1.1 μm band Peer-reviewed

    K. Koizumi, M. Yoshida, T. Hirooka, M. Nakazawa

    Conference on Lasers and Electro-Optics (CLEO 2011)　CMBB3　2011/05

  167. New PMD-induced crosstalk in the presence of PDL in a polarization-multiplexed ultrahigh-speed transmission Peer-reviewed

    T. Hirooka, T. Hirano, P. Guan, M. Nakazawa

    Optical Fiber Communication Conference (OFC 2011)　JThA44　2011/03

  168. Single-Channel 1.28 Tbit/s-525 km DQPSK Transmission Using Ultrafast Time-Domain Optical Fourier Transformation and Nonlinear Optical Loop Mirror Peer-reviewed

    Pengyu Guan, Hans Christian Hansen Mulvad, Yutaro Tomiyama, Toshiyuki Hirano, Toshihiko Hirooka, Masataka Nakazawa

    IEICE TRANSACTIONS ON COMMUNICATIONS　E94B　(2)　430-436　2011/02

    DOI： 10.1587/transcom.E94.B.430 　

    ISSN： 0916-8516

    eISSN： 1745-1345

  169. High time-resolution 640-Gb/s clock recovery using time-domain optical Fourier transformation and narrowband optical filter Peer-reviewed

    P. Guan, H. C, Hansen Mulvad, K. Kasai, T. Hirooka, M. Nakazawa

    IEEE Photonics Technology Letters　22　(23)　1735-1737　2010/12

    DOI： 10.1109/LPT.2010.2083644 　

  170. Recent progress on ultra-high speed and multi level coherent transmission Invited Peer-reviewed

    T. Hirooka, M. Nakazawa

    Photonics 2010　M2B3　2010/12

  171. High-resolution 640 Gbit/s clock recovery using time-domain optical Fourier transformation and narrowband optical filter Peer-reviewed

    H. C, Hansen Mulvad, P. Guan, K. Kasai, T. Hirooka, M. Nakazawa

    European Conference on Optical Communication (ECOC 2010)　Mo.1.A.6　2010/09

    DOI： 10.1109/ECOC.2010.5621124 　

  172. 1.28 Tbit/s/channel single-polarization DQPSK transmission over 525 km using ultrafast time-domain optical Fourier transformation Peer-reviewed

    P. Guan, H. C, Hansen Mulvad, Y. Tomiyama, T. Hirano, T. Hirooka, M. Nakazawa

    European Conference on Optical Communication (ECOC 2010)　We.6.C.3　2010/09

    DOI： 10.1109/ECOC.2010.5621133 　

  173. 640-Gb/s/Channel Single-Polarization DPSK Transmission Over 525 km With Ultrafast Time-Domain Optical Fourier Transformation Peer-reviewed

    Toshiyuki Hirano, Pengyu Guan, Toshihiko Hirooka, Masataka Nakazawa

    IEEE PHOTONICS TECHNOLOGY LETTERS　22　(14)　1042-1044　2010/07

    DOI： 10.1109/LPT.2010.2049483 　

    ISSN： 1041-1135

    eISSN： 1941-0174

  174. Single-channel 400-Gb/s OTDM-32 RZ/QAM coherent transmission over 225 km using an optical phase-locked loop technique Peer-reviewed

    K. Kasai, T. Omiya, P. Guan, M. Yoshida, T. Hirooka, M. Nakazawa

    IEEE Photonics Technology Letters　22　(8)　562-564　2010/04

    DOI： 10.1109/LPT.2010.2042708 　

  175. Single-channel 400 Gbit/s, OTDM-32 RZ/QAM coherent transmission over 225 km using an optical phase-locked loop technique Peer-reviewed

    K. Kasai, T. Omiya, P. Guan, M. Yoshida, T. Hirooka, M. Nakazawa

    Optical Fiber Communication Conference (OFC 2010)　OThD6　2010/03

  176. 640 Gbit/s single-polarization DPSK transmission over 525 km with time-domain optical Fourier transformation in a round-trip configuration Peer-reviewed

    T. Hirano, P. Guan, T. Hirooka, M. Nakazawa

    Optical Fiber Communication Conference (OFC 2010)　OThD7　2010/03

  177. 10 Gbit/s photonic crystal fiber transmissions with 1.1 μm directly-modulated single-mode VCSEL Peer-reviewed

    K. Koizumi, M. Yoshida, T. Hirooka, M. Nakazawa

    Optical Fiber Communication Conference (OFC 2010)　OWK3　2010/03

  178. Recent progress on OTDM Terabit/s transmission and their future Invited Peer-reviewed

    T. Hirooka

    Optical Fiber Communication Conference (OFC 2010)　OWM5　2010/03

  179. Low-Penalty 5 x 320 Gb/s/Single-Channel WDM DPSK Transmission Over 525 km Using Time-Domain Optical Fourier Transformation Peer-reviewed

    Pengyu Guan, Masatada Okazaki, Toshiyuki Hirano, Toshihiko Hirooka, Masataka Nakazawa

    IEEE PHOTONICS TECHNOLOGY LETTERS　21　(21)　1579-1581　2009/11

    DOI： 10.1109/LPT.2009.2029074 　

    ISSN： 1041-1135

  180. 10Gbit/s photonic crystal fiber transmissions with 1.1 mu m directly-modulated single-mode VCSEL Peer-reviewed

    Kengo Koizumi, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    IEICE ELECTRONICS EXPRESS　6　(22)　1615-1620　2009/11

    DOI： 10.1587/elex.6.1615 　

    ISSN： 1349-2543

  181. All-Optical Demultiplexing of 640-Gb/s OTDM-DPSK Signal Using a Semiconductor SMZ Switch Peer-reviewed

    Toshihiko Hirooka, Masatada Okazaki, Toshiyuki Hirano, Pengyu Guan, Masataka Nakazawa, Shigeru Nakamura

    IEEE PHOTONICS TECHNOLOGY LETTERS　21　(20)　1574-1576　2009/10

    DOI： 10.1109/LPT.2009.2029555 　

    ISSN： 1041-1135

    eISSN： 1941-0174

  182. All-optical demultiplexing of 640 Gbit/s OTDM-DPSK signal using a semiconductor SMZ switch Peer-reviewed

    T. Hirooka, M. Okazaki, T. Hirano, P. Guan, M. Nakazawa, S. Nakamura

    European Conference on Optical Communication (ECOC 2009)　4.3.2　2009/09

  183. Low-penalty 5x320 Gbit/s (1.6 Tbit/s) WDM DPSK transmission over 525 km using time-domain optical Fourier transformation Peer-reviewed

    P. Guan, M. Okazaki, T. Hirano, T. Hirooka, M. Nakazawa

    European Conference on Optical Communication (ECOC 2009)　6.4.4　2009/09

  184. Ultrafast transmission technology using time-domain optical Fourier transformation Invited Peer-reviewed

    T. Hirooka, M. Nakazawa

    IEEE/LEOS Summer Topicals 2009　MC2.4　2009/07

    DOI： 10.1109/LEOSST.2009.5226260 　

  185. All-Optical 40-GHz Time. Domain Fourier Transformation Using XPM With a Dark Parabolic Pulse Invited Peer-reviewed

    Toshihiko Hirooka, Masataka Nakazawa

    IEEE PHOTONICS TECHNOLOGY LETTERS　20　(21-24)　1869-1871　2008/11

    DOI： 10.1109/LPT.2008.2004879 　

    ISSN： 1041-1135

  186. 320-Gb/s Single-Polarization DPSK Transmission Over 525 km Using Time-Domain Optical Fourier Transformation Invited Peer-reviewed

    Toshihiko Hirooka, Masatada Okazaki, Pengyu Guan, Masataka Nakazawa

    IEEE PHOTONICS TECHNOLOGY LETTERS　20　(21-24)　1872-1874　2008/11

    DOI： 10.1109/LPT.2008.2004880 　

    ISSN： 1041-1135

  187. 160-Gb/s 200-km Field Transmission Experiment With Large PMD Using a Time-Domain Optical Fourier Transformation Technique Invited Peer-reviewed

    Masatada Okazaki, Pengyu Guan, Toshihiko Hirooka, Masataka Nakazawa, Tetsuya Miyazaki

    IEEE PHOTONICS TECHNOLOGY LETTERS　20　(21-24)　2192-2194　2008/11

    DOI： 10.1109/LPT.2008.2006407 　

    ISSN： 1041-1135

  188. A lambda/4-Shifted Distributed-Feedback Laser Diode With a Fiber Ring Cavity Configuration Having an OSNR of 85 dB and a Linewidth of 7 kHz Invited Peer-reviewed

    Ho Thi Quynhanh, Akihito Suzuki, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    IEEE PHOTONICS TECHNOLOGY LETTERS　20　(17-20)　1578-1580　2008/09

    DOI： 10.1109/LPT.2008.928848 　

    ISSN： 1041-1135

  189. 320 Gbit/s single-polarization DPSK transmission over 525 km using time-domain optical Fourier transformation Invited Peer-reviewed

    T. Hirooka, M. Okazaki, P. Guan, M. Nakazawa

    European Conference on Optical Communication (ECOC 2008)　2008/09

    DOI： 10.1109/ECOC.2008.4729323 　

  190. 160 Gbit/s-200 km field transmission experiment using a time-domain optical Fourier transformation technique with a large PMD Invited Peer-reviewed

    M. Okazaki, P. Guan, T. Hirooka, M. Nakazawa, T. Miyazaki

    European Conference on Optical Communication (ECOC 2008)　2008/09

    DOI： 10.1109/ECOC.2008.4729498 　

  191. Stimulated Brillouin Scattering in Ultrahigh-Speed In-Phase RZ and CS-RZ OTDM Transmission Invited Peer-reviewed

    Toshihiko Hirooka, Kou Osawa, Masatada Okazaki, Masataka Nakazawa, Hitoshi Murai

    IEEE PHOTONICS TECHNOLOGY LETTERS　20　(17-20)　1694-1696　2008/09

    DOI： 10.1109/LPT.2008.2003407 　

    ISSN： 1041-1135

  192. A straight-line 160-Gb/s DPSK transmission over 1000 km with time-domain optical Fourier transformation Invited Peer-reviewed

    Toshihiko Hirooka, Masatada Okazaki, Masataka Nakazawa

    IEEE PHOTONICS TECHNOLOGY LETTERS　20　(13-16)　1094-1096　2008/07

    DOI： 10.1109/LPT.2008.924303 　

    ISSN： 1041-1135

  193. Bright and dark 40 GHz parabolic pulse generation using a picosecond optical pulse train and an arrayed waveguide grating Invited Peer-reviewed

    T. Hirooka, M. Nakazawa, K. Okamoto

    Opt. Lett.　33　(10)　1102-1104　2008/05

    DOI： 10.1364/OL.33.001102 　

  194. 40 GHz bright and dark parabolic pulse generation using a picosecond optical pulse source and a 64-channel AWG, Peer-reviewed

    T. Hirooka, M. Nakazawa, K. Okamoto

    Optical Fiber Communication Conference (OFC2008)　OTuC6　2008/02

    DOI： 10.1109/OFC.2008.4528579 　

  195. All-optical 40 GHz time-domain Fourier transformation using XPM with a dark parabolic pulse Peer-reviewed

    T. Hirooka, M. Nakazawa

    Optical Fiber Communication Conference (OFC2008)　OThG5　2008/02

    DOI： 10.1109/OFC.2008.4528464 　

  196. Optical fiber transmission of standard signals using optical combs Peer-reviewed

    M. Nakazawa, T. Hirooka, M. Yoshida

    The Review of Laser Engineering (in Japanese)　35　(10)　649-653　2007/10

    Publisher: The Laser Society of Japan

    DOI： 10.2184/lsj.35.649 　

    ISSN： 0387-0200

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    Recently, the delivery of frequency standards using optical combs through optical fiber networks has become an important subject. When we transmit optical combs through an optical fiber network, it is very important to investigate the distortion in the power spectrum of the longitudinal modes that occurs during the transmission. In this paper, we describe the spectrum deformation of the longitudinal mode that occurs during long-haul transmission through a dispersion-shifted fiber, when we use a 10 GHz mode-locked fiber laser with a linewidth as narrow as 1 kHz as the signal source. We found that the deformation of the longitudinal mode power spectrum occurs mainly at the tail of the spectrum, and the linewidth broadening increases in proportion to the transmission distance. The main reason for the linewidth broadening was the phase fluctuation of the optical fiber caused by temperature fluctuation.

  197. 160 Gbit/s-900 km DPSK transmission with time-domain optical Fourier transformation Peer-reviewed

    T. Hirooka, M. Okazaki, K. Osawa, M. Nakazawa

    European Conference on Optical Communication (ECOC2007)　1.3.3　2007/09

  198. Observation of stimulated Brillouin scattering in ultrahigh-speed in-phase and carrier-suppressed RZ OTDM transmission Peer-reviewed

    T. Hirooka, K. Osawa, M. Okazaki, M. Nakazawa, H. Murai

    European Conference on Optical Communication (ECOC2007)　P085　2007/09

  199. Ultrahigh-speed signal transmission / processing technologies Invited Peer-reviewed

    T. Hirooka, M. Nakazawa

    Optoelectronics and Communications Conference (OECC2007)　Invited paper, 10B2-1　2007/07

  200. Low power-penalty 160 Gbit/s DPSK transmission over 600 km Peer-reviewed

    K. Osawa, M. Okazaki, T. Hirooka, M. Nakazawa

    Optoelectronics and Communications Conference (OECC2007)　10B2-2　2007/07

  201. Terabit OTDM transmission—Key challenges Invited Peer-reviewed

    M. Nakazawa, T. Hirooka

    IEEE/LEOS Summer Topicals 2007　Invited paper, ME3.3　2007/07

    DOI： 10.1109/LEOSST.2007.4288418 　

  202. 40 Gbit/s-2 km photonic crystal fibre transmission with 850 nm singlemode VCSEL Peer-reviewed

    H. Hasegawa, Y. Oikawa, T. Hirooka, M. Nakazawa

    ELECTRONICS LETTERS　43　(11)　642-644　2007/05

    DOI： 10.1049/el:20070171 　

    ISSN： 0013-5194

  203. 4 x 10 Gb/s WDM transmission over a 5-km-long photonic crystal fiber in the 800-nm region Peer-reviewed

    Yosuke Oikawa, Hideaki Hasegawa, Kenya Suzuki, Yasuyuki Inoue, Toshihiko Hirooka, Masataka Nakazawa

    IEEE PHOTONICS TECHNOLOGY LETTERS　19　(5-8)　613-615　2007/03

    DOI： 10.1109/LPT.2007.894354 　

    ISSN： 1041-1135

  204. Ultra-stable regeneratively mode-locked laser as an opto-electronic microwave oscillator and its application to optical metrology Peer-reviewed

    Masataka Nakazawa, Masato Yoshida, Toshihiko Hirooka

    IEICE TRANSACTIONS ON ELECTRONICS　E90C　(2)　443-449　2007/02

    DOI： 10.1093/ietele/e90-c.2.443 　

    ISSN： 0916-8524

    eISSN： 1745-1353

  205. 160-Gb/s-600-km OTDM transmission using time-domain optical Fourier transformation Peer-reviewed

    Toshihiko Hirooka, Ken-Ichi Hagiuda, Takashi Kumakura, Kou Osawa, Masataka Nakazawa

    IEEE PHOTONICS TECHNOLOGY LETTERS　18　(21-24)　2647-2649　2006/11

    DOI： 10.1109/LPT.2006.887770 　

    ISSN： 1041-1135

  206. Optical adaptive equalization of high-speed signals using time-domain optical Fourier transformation Peer-reviewed

    Toshihiko Hirooka, Masataka Nakazawa

    JOURNAL OF LIGHTWAVE TECHNOLOGY　24　(7)　2530-2540　2006/07

    DOI： 10.1109/JLT.2006.874647 　

    ISSN： 0733-8724

  207. Polymer saturable absorber materials in the 1.5 mu m band using poly-methyl-methacrylate and polystyrene with single-wall carbon nanotubes and their application to a femtosecond laser Peer-reviewed

    M Nakazawa, S Nakahara, T Hirooka, M Yoshida

    OPTICS LETTERS　31　(7)　915-917　2006/04

    DOI： 10.1364/OL.31.000915 　

    ISSN： 0146-9592

  208. 10Gb/s transmission over 5 km at 850nm using single-mode photonic crystal fiber, single-mode VCSEL, and Si-APD Peer-reviewed

    Hideaki Hasegawa, Yosuke Oikawa, Masato Yoshida, Toshihiko Hirooka, Masataka Nakazawa

    IEICE ELECTRONICS EXPRESS　3　(6)　109-114　2006/03

    DOI： 10.1587/elex.3.109 　

    ISSN： 1349-2543

  209. ABCD matrix formalism of time-domain optical Fourier transformation for distortion-free pulse transmission Peer-reviewed

    Masataka Nakazawa, Toshihiko Hirooka

    IEICE ELECTRONICS EXPRESS　3　(4)　74-79　2006/02

    DOI： 10.1587/elex.3.74 　

    ISSN： 1349-2543

  210. 10 Gb/s x 4 channel WDM transmission over a 3 km-long photonic crystal fiber in the 800 nm region

    Tohoku-Section Joint Convention Record of Institutes of Electrical and Information Engineers, Japan　2006　(0)　13-13　2006

    Publisher: Organizing Committee of Tohoku-Section Joint Convention of Institutes of Electrical and Information Engineers, Japan

    DOI： 10.11528/tsjc.2006.0_13 　

  211. Fiber transmission of microwave and optical standard signals using a mode-locked fiber laser in the GHz region

    Tohoku-Section Joint Convention Record of Institutes of Electrical and Information Engineers, Japan　2006　(0)　14-14　2006

    Publisher: Organizing Committee of Tohoku-Section Joint Convention of Institutes of Electrical and Information Engineers, Japan

    DOI： 10.11528/tsjc.2006.0_14 　

  212. Polymer saturable absorber materials in 1.5 #Gmu#GRm band using PMMA and PS with single-wall carbon nanotubes Peer-reviewed

    M. Nakazawa, S. Nakahara, T. Hirooka, M. Yoshida, T. Kaino, K. Komatsu

    Optical Fiber Communication Conference (OFC 2006)　2006

    More details Close

    通研ＤＢインポート

  213. 10 Gb/s transmission over 3 km at 850 nm using single-mode photonic crystal fiber, single-mode VCSEL, and Si-APD Peer-reviewed

    H. Hasegawa, Y. Oikawa, T. Hirooka, M. Yoshida, M. Nakazawa

    Optical Fiber Communication Conference (OFC 2006)　2006

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    通研ＤＢインポート

  214. Recent progress and future prospects for high-speed optical transmission technology using an ultrashort optical pulse train (Invited Paper) Peer-reviewed

    M. Nakazawa, T. Hirooka

    IEICE Transactions on Communications　J89-B　(11)　2067-2081　2006

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    通研インポート200703

  215. Ultra-broadband dispersion measurement of photonic crystal fiber with pico-second streak camera and group-delay-free supercontinuum Peer-reviewed

    Y. Oikawa, H. Hasegawa, T. Hirooka, M. Yoshida, M. Nakazawa

    IEICE Transactions on Electronics (in Japanese)　J89-C　(7)　450-457　2006

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 1345-2827

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    通研インポート200703

  216. Comparison of 40 GHz optical demultiplexers using SMZ switch and EA modulator in 160 Gbit/s-500 km OTDM transmission Peer-reviewed

    T. Hirooka, T. Kumakura, K. Osawa, M. Nakazawa

    European Optical Society Annual Meeting 2006, EOS Topical Meeting on Extreme Optics (TOM 2)　3　(17)　60-61　2006

    DOI： 10.1587/elex.3.397 　

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    通研インポート200703

  217. 160 Gbit/s-600 km OTDM transmission using time-domain optical Fourier transformation Peer-reviewed

    T. Hirooka, K. Hagiuda, T. Kumakura, K. Osawa, M. Nakazawa

    European Conference on Optical Communication (ECOC 2006)　Tu1.5.4　2006

    DOI： 10.1109/ECOC.2006.4801045 　

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    通研インポート200703

  218. 10 Gb/s x 4 channel WDM transmission over 3 km in the 800 nm region using photonic crystal fibers Peer-reviewed

    H. Hasegawa, Y. Oikawa, T. Hirooka, M. Yoshida, K. Suzuki, Y. Inoue, M. Nakazawa

    European Conference on Optical Communication (ECOC 2006)　We4.5.4　2006

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    通研インポート200703

  219. Distortion-free optical transmission using time-domain optical Fourier transformation and transform-limited optical pulses Peer-reviewed

    M Nakazawa, T Hirooka

    JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS　22　(9)　1842-1855　2005/09

    DOI： 10.1364/JOSAB.22.001842 　

    ISSN： 0740-3224

  220. 40-GHz, 100-fs stimulated-Brillouin-scattering-free pulse generation by combining a mode-locked laser diode and a dispersion-decreasing fiber Peer-reviewed

    K Hagiuda, T Hirooka, M Nakazawa

    OPTICS LETTERS　30　(6)　670-672　2005/03

    DOI： 10.1364/OL.30.000670 　

    ISSN： 0146-9592

  221. Stimulated Brillouin scattering in dispersion-decreasing fiber with ultrahigh-speed femtosecond soliton pulse compression Peer-reviewed

    T Hirooka, S Ono, K Hagiuda, M Nakazawa

    OPTICS LETTERS　30　(4)　364-366　2005/02

    DOI： 10.1364/OL.30.000364 　

    ISSN： 0146-9592

  222. Ultrahigh-speed distortion-free optical pulse transmission using time-domain optical Fourier transformation Peer-reviewed

    T. Hirooka, M. Nakazawa, F. Futami, S. Watanabe

    IEICE Trans. Comm. (in Japanese)　J88-B　(8)　1402-1410　2005

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    通研ＤＢインポート

  223. Distortion-free optical fiber transmission of ultrashort optical pulses using time-domain optical Fourier transformation Peer-reviewed

    M. Nakazawa, T. Hirooka

    Japanese Journal of Optics (in Japanese)　(1)　26-31　2005

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    通研ＤＢインポート

  224. Ultra-broadband dispersion measurement of a photonic crystal fiber with pico-second streak camera and group-delay-free supercontinuum Peer-reviewed

    Y. Oikawa, H. Hasegawa, M. Yoshida, T. Hirooka, M. Nakazawa

    International Conference on Quantum Electronics and the Pacific Rim Conference on Lasers and Electro-Optics (IQEC/CLEO-PR 2005)　2005

    DOI： 10.1109/CLEOPR.2005.1569514 　

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    通研ＤＢインポート

  225. Ultrahigh-speed distortion-free transmission using all-optical time-domain Fourier transformation (Invited paper) Peer-reviewed

    T. Hirooka, M. Nakazawa

    International Conference on Quantum Electronics and the Pacific Rim Conference on Lasers and Electro-Optics (IQEC/CLEO-PR 2005)　2005

    DOI： 10.1109/CLEOPR.2005.1569852 　

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    通研ＤＢインポート

  226. Observation of optimum air-hole tapering of splicing between a conventional fiber and a photonic crystal fiber and analysis of reduction of Fresnel reflection Peer-reviewed

    H. Hasegawa, M. Kikegawa, M. Yoshida, T. Hirooka, M. Nakazawa

    International Conference on Quantum Electronics and the Pacific Rim Conference on Lasers and Electro-Optics (IQEC/CLEO-PR 2005)　J88-C　(10)　779-787　2005

    DOI： 10.1109/CLEOPR.2005.1569517 　

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    通研ＤＢインポート

  227. Derivation of analytical expression for third-order dispersion elimination using time-domain optical Fourier transformation Peer-reviewed

    Toshihiko Hirooka, Masataka Nakazawa

    IET Conference Publications　2005　(502)　653-654　2005

    Publisher: Institution of Engineering and Technology

    DOI： 10.1049/cp:20050655 　

  228. Measurement of optical carrier spectrum deformation in high-speed pulse transmission Peer-reviewed

    K. Osawa, K. Haneda, T. Hirooka, M. Yoshida, W. Suttawassuntorn, M. Nakazawa

    International Conference on Quantum Electronics and the Pacific Rim Conference on Lasers and Electro-Optics (IQEC/CLEO-PR 2005)　2005

    DOI： 10.1109/CLEOPR.2005.1569851 　

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    通研ＤＢインポート

  229. A new method for optimum dispersion designing of zero-dispersion and dispersion-flattened photonic crystal fibers Peer-reviewed

    H. Hasegawa, T. Hirooka, M. Nakazawa

    International Conference on Quantum Electronics and the Pacific Rim Conference on Lasers and Electro-Optics (IQEC/CLEO-PR 2005)　J88-C　(7)　519-527　2005

    DOI： 10.1109/CLEOPR.2005.1569519 　

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    通研ＤＢインポート

  230. A new adaptive equalization scheme for a 160-Gb/s transmitted signal using time-domain optical Fourier transformation Peer-reviewed

    T Hirooka, M Nakazawa, F Futami, S Watanabe

    IEEE PHOTONICS TECHNOLOGY LETTERS　16　(10)　2371-2373　2004/10

    DOI： 10.1109/LPT.2004.834450 　

    ISSN： 1041-1135

  231. New adaptive equalization scheme for 160 Gb/s transmitted signal using time-domain optical Fourier transformation Peer-reviewed

    T. Hirooka, M. Nakazawa, F. Futami, S. Watanabe

    30th European Conference on Optical Communication　Paper Th1.5.3　2004/09

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    <RIEC><DUMMY>あ</DUMMY><BIBID>2003500798</BIBID></RIEC>

  232. Generation of a 40-GHz, 100-fs pulse train from a mode-locked laser diode using DDF soliton compression Peer-reviewed

    K. Hagiuda, T. Hirooka, S. Ono, M. Yoshida, M. Nakazawa, S. Arahira, Y. Ogawa

    30th European Conference on Optical Communication　Paper Tu3.3.2　2004/09

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    <RIEC><DUMMY>あ</DUMMY><BIBID>2003500796</BIBID></RIEC>

  233. Stimulated Brillouin scattering in ultrahigh-speed femtosecond soliton compression with a dispersion-decreasing fiber Peer-reviewed

    T. Hirooka, S. Ono, K. Hagiuda, M. Nakazawa

    14th International Conference on Ultrafast Phenomena　Paper TuE38　2004/09

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    <RIEC><DUMMY>あ</DUMMY><BIBID>2003500792</BIBID></RIEC>

  234. Gaussian and sech approximations of mode field profiles in photonic crystal fibers Peer-reviewed

    T Hirooka, Y Hori, M Nakazawa

    IEEE PHOTONICS TECHNOLOGY LETTERS　16　(4)　1071-1073　2004/04

    DOI： 10.1109/LPT.2004.824950 　

    ISSN： 1041-1135

  235. Ideal distortion-free transmission using optical Fourier transformation and Fourier transform-limited optical pulses Peer-reviewed

    M Nakazawa, T Hirooka, F Futami, S Watanabe

    IEEE PHOTONICS TECHNOLOGY LETTERS　16　(4)　1059-1061　2004/04

    DOI： 10.1109/LPT.2004.824969 　

    ISSN： 1041-1135

  236. Parabolic pulse generation by use of a dispersion-decreasing fiber with normal group-velocity dispersion Peer-reviewed

    T Hirooka, M Nakazawa

    OPTICS LETTERS　29　(5)　498-500　2004/03

    DOI： 10.1364/OL.29.000498 　

    ISSN： 0146-9592

  237. Ideal distortion-free transmission using optical Fourier transformation and transform-limited ultrashort pulses Peer-reviewed

    M. Nakazawa, T. Hirooka, F. Futami, S. Watanabe

    European Conference on Optical Communication, Post-deadline paper, Th4.3.8　2003/09

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    <RIEC><DUMMY>あ</DUMMY><BIBID>2003500281</BIBID></RIEC>

  238. Incomplete collisions in strongly dispersion-managed return-to-zero communication systems Peer-reviewed

    MJ Ablowitz, A Docherty, T Hirooka

    OPTICS LETTERS　28　(14)　1191-1193　2003/07

    DOI： 10.1364/OL.28.001191 　

    ISSN： 0146-9592

  239. Analysis of timing and amplitude jitter due to intrachannel dispersion-managed pulse interactions Peer-reviewed

    T Hirooka, MJ Ablowitz

    IEEE PHOTONICS TECHNOLOGY LETTERS　14　(5)　633-635　2002/05

    DOI： 10.1109/68.998708 　

    ISSN： 1041-1135

  240. Resonant intrachannel pulse interactions in dispersion-managed transmission systems Peer-reviewed

    MJ Ablowitz, T Hirooka

    IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS　8　(3)　603-615　2002/05

    DOI： 10.1109/JSTQE.2002.1016364 　

    ISSN： 1077-260X

  241. Collision-induced timing shifts in dispersion-managed soliton systems Peer-reviewed

    MJ Ablowitz, G Biondini, A Biswas, A Docherty, T Hirooka, S Chakravarty

    OPTICS LETTERS　27　(5)　318-320　2002/03

    DOI： 10.1364/OL.27.000318 　

    ISSN： 0146-9592

  242. Suppression of intrachannel dispersion-managed pulse interactions by distributed amplification Peer-reviewed

    T Hirooka, MJ Ablowitz

    IEEE PHOTONICS TECHNOLOGY LETTERS　14　(3)　316-318　2002/03

    DOI： 10.1109/68.986798 　

    ISSN： 1041-1135

  243. Intrachannel pulse interactions in dispersion-managed transmission systems: energy transfer Peer-reviewed

    MJ Ablowitz, T Hirooka

    OPTICS LETTERS　27　(3)　203-205　2002/02

    DOI： 10.1364/OL.27.000203 　

    ISSN： 0146-9592

  244. Higher-order asymptotic analysis of dispersion-managed transmission systems: solutions and their characteristics Peer-reviewed

    Mark J. Ablowitz, Toshihiko Hirooka, Takashi Inoue

    Journal of the Optical Society of America B　11　(12)　2876-2885　2002

  245. Managing nonlinearity in strongly dispersion managed optical pulse transmission Peer-reviewed

    Toshihiko Hirooka, Mark J. Ablowitz

    Nonlinear Optics 2002　WE1　(3)　204-206　2002

  246. Timing and amplitude jitter due to intra-channel dispersion-managed pulse interactions Peer-reviewed

    Toshihiko Hirooka, Mark J. Ablowitz

    Nonlinear Guided Waves and Their Applications 2002　NL MD54-1-NL MD54-3　2002

  247. Intrachannel pulse interactions in dispersion-managed transmission systems: timing shifts Peer-reviewed

    MJ Ablowitz, T Hirooka

    OPTICS LETTERS　26　(23)　1846-1848　2001/12

    DOI： 10.1364/OL.26.001846 　

    ISSN： 0146-9592

  248. Nonlinear effects in quasi-linear dispersion-managed pulse transmission Peer-reviewed

    MJ Ablowitz, T Hirooka

    IEEE PHOTONICS TECHNOLOGY LETTERS　13　(10)　1082-1084　2001/10

    DOI： 10.1109/68.950742 　

    ISSN： 1041-1135

  249. Quasi-linear optical pulses in strongly dispersion-managed transmission systems Peer-reviewed

    MJ Ablowitz, T Hirooka, G Biondini

    OPTICS LETTERS　26　(7)　459-461　2001/04

    DOI： 10.1364/OL.26.000459 　

    ISSN： 0146-9592

  250. Resonant intrachannel four-wave mixing in strongly dispersion-managed transmission systems Peer-reviewed

    M. J. Ablowitz, T. Hirooka

    Conference on Optical Fiber Communications (OFC 2001)　WDD33　2001/03

  251. Quasi-linear optical pulses in strongly dispersion-managed transmission systems Peer-reviewed

    M. J. Ablowitz, T. Hirooka, G. Biondini, W. L. Kath

    Nonlinear Guided Waves and Their Applications (NLGW 2001)　MC76　2001/03

  252. Resonant nonlinear intrachannel interactions in strongly dispersion-managed transmission systems Peer-reviewed

    MJ Ablowitz, T Hirooka

    OPTICS LETTERS　25　(24)　1750-1752　2000/12

    DOI： 10.1364/OL.25.001750 　

    ISSN： 0146-9592

  253. Effect of map strength on polarization mode dispersion in dispersion-managed soliton systems Peer-reviewed

    Nishioka, I, T Hirooka, A Hasegawa

    IEEE PHOTONICS TECHNOLOGY LETTERS　12　(11)　1480-1482　2000/11

    DOI： 10.1109/68.887693 　

    ISSN： 1041-1135

  254. Feasibility of densely dispersion managed soliton transmission at 160 Gb/s Peer-reviewed

    T Hirooka, T Nakada, A Hasegawa

    IEEE PHOTONICS TECHNOLOGY LETTERS　12　(6)　633-635　2000/06

    DOI： 10.1109/68.849067 　

    ISSN： 1041-1135

  255. Nonlinear gain control of dispersion-managed soliton amplitude and collisions Peer-reviewed

    T Hirooka, S Wabnitz

    OPTICAL FIBER TECHNOLOGY　6　(2)　109-121　2000/04

    DOI： 10.1006/ofte.1999.0325 　

    ISSN： 1068-5200

  256. Stable filter control in wavelength division multiplexed soliton systems Peer-reviewed

    A. Hasegawa, T. Hirooka

    Electronics Letters　36　(1)　68-70　2000/01

    DOI： 10.1049/el:20000113 　

  257. 160 Gb/s soliton transmission in a densely dispersion-managed fiber in the presence of variable dispersion and polarization-mode dispersion Peer-reviewed

    T. Hirooka, T. Nakada, A. H. Liang, A. Hasegawa

    Nonlinear Guided Waves and Their Applications (NLGW '99)　ThA2　1999/09

  258. Stabilisation of dispersion-managed soliton transmissions by nonlinear gain Peer-reviewed

    T Hirooka, S Wabnitz

    ELECTRONICS LETTERS　35　(8)　655-657　1999/04

    DOI： 10.1049/el:19990463 　

    ISSN： 0013-5194

  259. Quasi-soliton propagation with periodic optical phase conjugation Peer-reviewed

    T Hirooka, A Hasegawa

    ELECTRONICS LETTERS　34　(21)　2056-2057　1998/10

    DOI： 10.1049/el:19981378 　

    ISSN： 0013-5194

  260. Chirped soliton interaction in strongly dispersion managed WDM systems Peer-reviewed

    T. Hirooka, A. Hasegawa

    Optics Letters.　23　(10)　768-770　1998/05

  261. Wavelength division multiplexing with quasi soliton systems Peer-reviewed

    T. Hirooka, A. Hasegawa

    Conference on Optical Fiber Communications (OFC '98)　ThI1　1998/02

  262. Demultiplexing in wavelength division multiplexed soliton transmission systems Invited Peer-reviewed

    T. Hirooka, A. Hasegawa

    The Pacific Conference on Lasers and Electro-Optics (CLEO/Pacific Rim '97)　Invited paper, WJ1　1997/07

Show all ︎Show first 5

Misc. 118

  1. Performance comparison of injection-locked carrier frequency conversion and self-heterodyne detection methods in cohelently-linked optical and wireless transmission

    佐藤大晟, 佐藤大晟, 白幡晃一, 白幡晃一, 葛西恵介, 廣岡俊彦, 吉田真人, 中沢正隆

    電子情報通信学会技術研究報告(Web)　121　(320(OCS2021 33-40))　2022

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  2. Recent progress and challenges toward ultrahigh-speed transmission beyond 10 Tbit/s with optical Nyquist pulses

    Masataka Nakazawa, Masato Yoshida, Toshihiko Hirooka

    IEICE ELECTRONICS EXPRESS　18　(7)　2021/04

    DOI： 10.1587/elex.18.20212001 　

    ISSN： 1349-2543

  3. Single-channel 1.28 Tbit/s Optical Nyquist Pulse Transmission over 3000 km

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    電子情報通信学会大会講演論文集(CD-ROM)　2021　2021

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  4. Performance comparison between Fabry-Perot LD based- and ECLD based-injection-locking circuits

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    電子情報通信学会大会講演論文集(CD-ROM)　2021　2021

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  5. Study on Chromatic Dispersion Dependence of GAWBS Noise

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    電子情報通信学会大会講演論文集(CD-ROM)　2021　2021

    ISSN： 1349-144X

  6. 12.8 Tbit/s (1.28 Tbit/s/ch x 10) OTDM-WDM Transmission of PDM-DQPSK Optical Nyquist Pulses over 1500 km

    渡邊碧, 吉田真人, 廣岡俊彦, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2021　2021

    ISSN： 1349-144X

  7. BER performance improvement of ultrahigh-speed coherent Nyquist pulse transmission using low-nonlinearity, dispersion-compensated transmission line with chirped FBG and LCoS

    木村光佑, 木村光佑, 吉田真人, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会技術研究報告(Web)　121　(18(OFT2021 1-11))　2021

    ISSN： 2432-6380

  8. Precise and Wideband Compensation of WDM Inter-Channel Cross-Phase Modulation Noise Using Injection Locking

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    電子情報通信学会大会講演論文集(CD-ROM)　2021　2021

    ISSN： 1349-144X

  9. Low-Nonlinearity, Dispersion-Compensated Transmission Line with a Chirped Fiber Bragg Grating and LCoS and Its Application to Ultrahigh-Speed Coherent Nyquist Pulse Transmission

    岩屋太郎, 木村光佑, 吉田真人, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2021　2021

    ISSN： 1349-144X

  10. Toward optical and wireless convergence with coherently-linked access network

    廣岡俊彦, 葛西恵介, 吉田真人, 中沢正隆

    電子情報通信学会技術研究報告(Web)　120　(341(SR2020 47-59))　2021

    ISSN： 2432-6380

  11. Study on chromatic dispersion dependence of GAWBS noise

    佐藤耕造, 管貴志, 吉田真人, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会技術研究報告(Web)　120　(309(OCS2020 27-39))　2021

    ISSN： 2432-6380

  12. 12.8 Tbit/s (1.28 Tbit/s/ch x 10) OTDM-WDM Transmission of PDM-DQPSK Optical Nyquist Pulses over 1500 km

    渡邊碧, 吉田真人, 廣岡俊彦, 中沢正隆

    電子情報通信学会技術研究報告(Web)　120　(309(OCS2020 27-39))　2021

    ISSN： 2432-6380

  13. Next Generation C-RAN Mobile Fronthaul Using On-line Bi-directional 256 QAM WDM Coherent Transmission

    管貴志, 吉田真人, 葛西恵介, 廣岡俊彦, 岩月勝美, 中沢正隆

    電子情報通信学会技術研究報告　119　(366(OCS2019 65-77)(Web))　2020

    ISSN： 0913-5685

  14. Effect of GAWBS Depolarization Noise on Digital Coherent Optical Transmission

    竹節直也, 吉田真人, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2020　2020

    ISSN： 1349-144X

  15. A proposal on optical-wireless mobile fronthaul for advanced 5G

    中沢正隆, 葛西恵介, 吉田真人, 廣岡俊彦, 岩月勝美

    電子情報通信学会大会講演論文集(CD-ROM)　2020　2020

    ISSN： 1349-144X

  16. Single-channel 15.3 Tbit/s, 64 QAM coherent Nyquist pulse transmission over 150 km

    木村光佑, 吉田真人, 岩屋太郎, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2020　2020

    ISSN： 1349-144X

  17. 10 Tbit/s QAM quantum noise stream cipher coherent transmission over 160 km

    吉田真人, 管貴志, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2020　2020

    ISSN： 1349-144X

  18. Experimental and theoretical analyses of GAWBS phase noise in multi-core fibers for digital coherent transmission

    吉田真人, 竹節直也, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会技術研究報告(Web)　120　(140(OCS2020 4-7))　2020

    ISSN： 2432-6380

  19. 160 Gbit/s, 256 QAM bidirectional coherent transmission for mobile fronthaul without backward Rayleigh scattering interference

    葛西恵介, 吉田真人, 廣岡俊彦, 岩月勝美, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2020　2020

    ISSN： 1349-144X

  20. Experimental and theoretical analyses of GAWBS noise in multi-core fiber

    吉田真人, 竹節直也, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2020　2020

    ISSN： 1349-144X

  21. 50.4 Tbit/s, L-band 480 ch-WDM, 128 QAM-160 km Digital Coherent Optical Transmission Using an Injection-locked Homodyne Receiver

    管貴志, 葛西恵介, 吉田真人, 廣岡俊彦, 中沢正隆

    電子情報通信学会技術研究報告　119　(93(OCS2019 10-19)](Web))　2019

    ISSN： 0913-5685

  22. 次世代モバイルフロントホール用256QAMオンライン双方向コヒーレント伝送

    吉田真人, 管貴志, 葛西恵介, 廣岡俊彦, 岩月勝美, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2019　2019

    ISSN： 1349-144X

  23. リアルタイム偏波多重256~512QAMデジタルコヒーレント光伝送

    吉田真人, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2019　2019

    ISSN： 1349-144X

  24. 256QAM WDMオンライン双方向コヒーレント伝送を用いた次世代C-RANモバイルフロントホール

    管貴志, 吉田真人, 葛西恵介, 廣岡俊彦, 岩月勝美, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2019　2019

    ISSN： 1349-144X

  25. デジタルコヒーレント光伝送における各種ファイバのGAWBS雑音特性

    竹節直也, 吉田真人, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2019　2019

    ISSN： 1349-144X

  26. 50.4Tbit/s,L-band WDM128QAM-160kmコヒーレント光伝送

    管貴志, 葛西恵介, 吉田真人, 廣岡俊彦, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2019　2019

    ISSN： 1349-144X

  27. 非線形光ループミラーを用いたフルCバンドサブピコ秒光スイッチ

    平田綾也, 廣岡俊彦, 吉田真人, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2019　2019

    ISSN： 1349-144X

  28. 単一チャンネル7.68Tbit/s-150km,64QAMコヒーレントナイキストパルス伝送

    新田純平, 木村光佑, 吉田真人, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2018　2018

    ISSN： 1349-144X

  29. 光注入同期法を用いた次世代モバイルフロントホール用160Gbit/s,256QAMデジタルコヒーレント伝送

    葛西恵介, WANG Yixin, 吉田真人, 廣岡俊彦, 岩月勝美, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2018　2018

    ISSN： 1349-144X

  30. 注入同期法を用いた12bit/s/Hz,58.2Tbit/s,256QAM-160km CバンドWDM伝送

    管貴志, 葛西恵介, 吉田真人, 廣岡俊彦, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2018　2018

    ISSN： 1349-144X

  31. 単一チャネル10.2Tbit/s-300km光ナイキストパルス伝送

    平田綾也, WANG Jianping, 廣岡俊彦, 吉田真人, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2018　2018

    ISSN： 1349-144X

  32. GAWBS位相雑音補償による1024QAMコヒーレント光伝送におけるエラーフロアの抑制

    吉田真人, 竹節直也, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2018　2018

    ISSN： 1349-144X

  33. PS-4096QAM信号と1024QAM信号の160km伝送特性比較

    岡本聖司, 岡本聖司, 寺山雅樹, 吉田真人, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2018　2018

    ISSN： 1349-144X

  34. 光ナイキストパルスを用いた単一チャネル10Tbit/s級超高速伝送

    廣岡俊彦, 吉田真人, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2018　2018

    ISSN： 1349-144X

  35. 12 bit/s/Hz, 58.2 Tbit/s, 256 QAM-160 km C-band WDM Transmission Using an Injection Locking Technique

    管貴志, 葛西恵介, 吉田真人, 廣岡俊彦, 中沢正隆

    電子情報通信学会技術研究報告　118　(238(OFT2018 13-51)(Web))　2018

    ISSN： 0913-5685

  36. Observation of GAWBS Noise and Development of its Compensation Technique in Digital Coherent Optical Transmission

    竹節直也, 吉田真人, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会技術研究報告　118　(238(OFT2018 13-51)(Web))　2018

    ISSN： 0913-5685

  37. 単一チャネル3.84Tbit/s,64QAMコヒーレントナイキストパルス信号の150km伝送

    新田純平, 木村光佑, 吉田真人, 葛西恵介, 廣岡俊彦, 中沢正隆

    電子情報通信学会大会講演論文集(CD-ROM)　2017　2017

    ISSN： 1349-144X

  38. High Spectral Efficient Transmission with Digital Coherent Ultra-multilevel QAM Format

    45　(12)　466-471　2016/12

    Publisher: 日本光学会

    ISSN： 0389-6625

  39. B-10-61 Q-factor analysis of dispersion and nonlinear impairments in ultrahigh-speed Nyquist pulse transmission

    Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2016　(2)　354-354　2016/03/01

    Publisher: The Institute of Electronics, Information and Communication Engineers

  40. B-10-38 Real-time adaptive 4-64 QAM, 20-60 Gbit/s quantum noise stream cipher transmission

    Nakazawa Masataka, Yoshida Masato, Hirooka Toshihiko, Kasai Keisuke

    Proceedings of the IEICE General Conference　2016　(2)　331-331　2016/03/01

    Publisher: The Institute of Electronics, Information and Communication Engineers

  41. B-10-46 2.56 Tbit/s/ch DQPSK Non-Coherent Nyquist Pulse Transmission over 525 km

    Harako Koudai, Seya Daiki, Suzuki Daiki, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2015　(2)　210-210　2015/08/25

    Publisher: The Institute of Electronics, Information and Communication Engineers

  42. B-10-50 1024 QAM, 7-core (60 Gbit/s x 7) fiber transmission over 55 km with an aggregate spectral efficiency of 109 bit/s/Hz

    Yoshida Masato, Beppu Shohei, Kasai Keisuke, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2015　(2)　214-214　2015/08/25

    Publisher: The Institute of Electronics, Information and Communication Engineers

  43. B-10-57 QAM quantum noise stream cipher using digital coherent optical transmission

    Nakazawa Masataka, Yoshida Masato, Hirooka Toshihiko, Kasai Keisuke

    Proceedings of the Society Conference of IEICE　2015　(2)　221-221　2015/08/25

    Publisher: The Institute of Electronics, Information and Communication Engineers

  44. B-10-26 1.92 Tbit/s/ch, 64 QAM coherent Nyquist pulse transmission with a spectral efficiency of 10.6 bit/s/Hz

    Otuya David Odeke, Harako Koudai, Kasai Keisuke, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2015　(2)　362-362　2015/02/24

    Publisher: The Institute of Electronics, Information and Communication Engineers

  45. High-performance TDM demultiplexing of coherent Nyquist pulses using time-domain orthogonality

    HARAKO Koudai, OTUYA David Odeke, KASAI Keisuke, HIROOKA Toshihiko, NAKAZAWA Masataka

    Technical report of IEICE. OCS　114　(281)　97-100　2014/10/30

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    We propose a simple and high-performance scheme for demultiplexing coherent Nyquist TDM signals by photo-mixing on a photo-detector with Nyquist LO pulses. This scheme takes advantage of the time-domain orthogonality of Nyquist pulses, which enables high-SNR demultiplexing and homodyne detection simultaneously in spite of a strong overlap with adjacent pulses in the time domain. The feasibility of this scheme is demonstrated through a demultiplexing experiment employing 80 Gbaud, 64 QAM Nyquist pulse OTDM signals. This scheme exhibits excellent demultiplexing performance with a much simpler configuration than a conventional ultrafast all-optical sampling scheme.

  46. B-10-29 High Speed, Low Penalty Optical Demultiplexing Using Nonlinear Optical Loop Mirror With a Nyquist Control Pulse

    Seya Daiki, Harako Kodai, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2014　(2)　397-397　2014/03/04

    Publisher: The Institute of Electronics, Information and Communication Engineers

  47. B-10-28 100 Gbit/s real-time digital coherent transmission over a 32 km multi-mode graded-index fiber

    Hirooka Toshihiko, Nakazawa Masataka, Komukai Tetsuro, Sakano Toshikazu

    Proceedings of the IEICE General Conference　2014　(2)　396-396　2014/03/04

    Publisher: The Institute of Electronics, Information and Communication Engineers

  48. 1.28 Tbit/s/ch optical Nyquist transmission over 525 km with substantial PMD tolerance

    Harako Kodai, Seya Daiki, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2013　(2)　241-241　2013/09/03

    Publisher: The Institute of Electronics, Information and Communication Engineers

  49. 1.28 Tbit/s-58 km single-channel transmmission at 1.1μm

    Koizumi Kengo, Yoshida Masato, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2013　(2)　240-240　2013/09/03

    Publisher: The Institute of Electronics, Information and Communication Engineers

  50. 光多値化技術とさらなる周波数利用効率向上に向けて (特集 光ファイバー通信の新たなブレークスルーへ向けて)

    中沢 正隆, 廣岡 俊彦, 吉田 真人

    O plus E : Optics・Electronics　35　(8)　836-841　2013/08

    Publisher: アドコム・メディア

    ISSN： 0911-5943

  51. TK-3-8 Optical Interconnections Suitable for Resiliellt ICT

    Kubota Hirokazu, Komukai Tetsuro, Sakano Toshikazu, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2013　(2)　"SSS-32"-"SSS-33"　2013/03/05

    Publisher: The Institute of Electronics, Information and Communication Engineers

  52. TK-3-7 Optical Transmission Technologies for Enhancing the Resilience of Information and Communication Networks

    Morita Itsuro, Yoshikane Noboru, Tsuritani Takehiro, Hirooka Toshihiko, Yoshida Masato, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2013　(2)　"SSS-30"-"SSS-31"　2013/03/05

    Publisher: The Institute of Electronics, Information and Communication Engineers

  53. B-10-66 Highly dispersion-tolerant 160 Gbaud optical Nyquist pulse TDM transmission over 525 km

    Hirooka Toshihiko, Ruan Peng, Guan Pengyu, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2012　(2)　248-248　2012/08/28

    Publisher: The Institute of Electronics, Information and Communication Engineers

  54. B-10-34 Marked performance improvement of 256 QAM transmission using a digital back-propagation method

    Toyoda Kazushi, Koizumi Yuki, Omiya Tatsunori, Yoshida Masato, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2012　(2)　216-216　2012/08/28

    Publisher: The Institute of Electronics, Information and Communication Engineers

  55. B-10-62 1.1 μm, 160 Gbit/s OTDM transmission over 30 km

    Koizumi Kengo, Hirooka Toshihiko, Yoshida Masato, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2012　(2)　244-244　2012/08/28

    Publisher: The Institute of Electronics, Information and Communication Engineers

  56. 1.07μm passively mode-locked ytterbium-doped fiber laser with SWNT/PMMA saturable absorber

    YOSHIDA Masato, HORI Yuichiro, HIROOKA Toshihiko, NAKAZAWA Masataka

    IEICE technical report. Component parts and materials　112　(182)　83-86　2012/08/16

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    Single-wall carbon nanotubes (SWNT) have received considerable attention as a nonlinear optical material for ultrashort lasers and optical switch devices because of their attractive features such as ultrafast saturable absorption (SA) effects with a recovery time of faster than 1 ps. The SA wavelength depends on the tube diameter. We previously reported an SWNT polymer material that used polymethylmethacrylate (PMMA) and applied it to a passively mode-locked Er fiber laser for 171 fs pulse generation at 1.55 μm. In this report, we describe a mode-locked Yb-doped fiber laser for femtosecond pulse generation at 1.1 μm realized by using an SWNT/PMMA wafer in the cavity. By optimizing the cavity configuration as a dispersion-managed soliton laser, we obtained a 543 fs, 15.1 MHz pulse train.

  57. Increase of Output Power of Passively Mode-Locked Fiber Laser with a SWNT

    ONO Takato, HORI Yuichiro, YOSHIDA Masato, HIROOKA Toshihiko, NAKAZAWA Masataka, MATA Junji, TSUKAMOTO Jun

    IEICE technical report. Component parts and materials　112　(182)　87-90　2012/08/16

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    We have demonstrated a passively mode-locked fiber laser with SWNT-based saturable absorbers made by uniformly dispersing SWNTs into polymer such as poly methyl methacrylate, or by depositing SWNTs on the optical fiber end. However, the output power of the lasers is limited to less than 10 mW due to relatively low tolerance to optical damage of these SWNT-based saturable absorbers. In this work, we fabricated a SWNT saturable absorber with a substantial increase in the optical damage threshold by sealing SWNT with siloxane which has a high heat resistance. By installing this saturable absorber in a passively mode-locked fiber laser, a 31 mW, 280 fs ultrashort pulse was successfully generated.

  58. 1.07μm passively mode-locked ytterbium-doped fiber laser with SWNT/PMMA saturable absorber

    YOSHIDA Masato, HORI Yuichiro, HIROOKA Toshihiko, NAKAZAWA Masataka

    IEICE technical report. Reliability　112　(180)　83-86　2012/08/16

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    Single-wall carbon nanotubes (SWNT) have received considerable attention as a nonlinear optical material for ultrashort lasers and optical switch devices because of their attractive features such as ultrafast saturable absorption (SA) effects with a recovery time of faster than 1 ps. The SA wavelength depends on the tube diameter. We previously reported an SWNT polymer material that used polymethylmethacrylate (PMMA) and applied it to a passively mode-locked Er fiber laser for 171 fs pulse generation at 1.55 μm. In this report, we describe a mode-locked Yb-doped fiber laser for femtosecond pulse generation at 1.1 μm realized by using an SWNT/PMMA wafer in the cavity. By optimizing the cavity configuration as a dispersion-managed soliton laser, we obtained a 543 fs, 15.1 MHz pulse train.

  59. Increase of Output Power of Passively Mode-Locked Fiber Laser with a SWNT

    ONO Takato, HORI Yuichiro, YOSHIDA Masato, HIROOKA Toshihiko, NAKAZAWA Masataka, MATA Junji, TSUKAMOTO Jun

    IEICE technical report. Reliability　112　(180)　87-90　2012/08/16

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    We have demonstrated a passively mode-locked fiber laser with SWNT-based saturable absorbers made by uniformly dispersing SWNTs into polymer such as poly methyl methacrylate, or by depositing SWNTs on the optical fiber end. However, the output power of the lasers is limited to less than 10 mW due to relatively low tolerance to optical damage of these SWNT-based saturable absorbers. In this work, we fabricated a SWNT saturable absorber with a substantial increase in the optical damage threshold by sealing SWNT with siloxane which has a high heat resistance. By installing this saturable absorber in a passively mode-locked fiber laser, a 31 mW, 280 fs ultrashort pulse was successfully generated.

  60. 1.07μm passively mode-locked ytterbium-doped fiber laser with SWNT/PMMA saturable absorber

    YOSHIDA Masato, HORI Yuichiro, HIROOKA Toshihiko, NAKAZAWA Masataka

    IEICE technical report. EMD　112　(181)　83-86　2012/08/16

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    Single-wall carbon nanotubes (SWNT) have received considerable attention as a nonlinear optical material for ultrashort lasers and optical switch devices because of their attractive features such as ultrafast saturable absorption (SA) effects with a recovery time of faster than 1 ps. The SA wavelength depends on the tube diameter. We previously reported an SWNT polymer material that used polymethylmethacrylate (PMMA) and applied it to a passively mode-locked Er fiber laser for 171 fs pulse generation at 1.55 μm. In this report, we describe a mode-locked Yb-doped fiber laser for femtosecond pulse generation at 1.1 μm realized by using an SWNT/PMMA wafer in the cavity. By optimizing the cavity configuration as a dispersion-managed soliton laser, we obtained a 543 fs, 15.1 MHz pulse train.

  61. Increase of Output Power of Passively Mode-Locked Fiber Laser with a SWNT

    ONO Takato, HORI Yuichiro, YOSHIDA Masato, HIROOKA Toshihiko, NAKAZAWA Masataka, MATA Junji, TSUKAMOTO Jun

    IEICE technical report. EMD　112　(181)　87-90　2012/08/16

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    We have demonstrated a passively mode-locked fiber laser with SWNT-based saturable absorbers made by uniformly dispersing SWNTs into polymer such as poly methyl methacrylate, or by depositing SWNTs on the optical fiber end. However, the output power of the lasers is limited to less than 10 mW due to relatively low tolerance to optical damage of these SWNT-based saturable absorbers. In this work, we fabricated a SWNT saturable absorber with a substantial increase in the optical damage threshold by sealing SWNT with siloxane which has a high heat resistance. By installing this saturable absorber in a passively mode-locked fiber laser, a 31 mW, 280 fs ultrashort pulse was successfully generated.

  62. 1.07μm passively mode-locked ytterbium-doped fiber laser with SWNT/PMMA saturable absorber

    YOSHIDA Masato, HORI Yuichiro, HIROOKA Toshihiko, NAKAZAWA Masataka

    Technical report of IEICE. OPE　112　(183)　83-86　2012/08/16

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    Single-wall carbon nanotubes (SWNT) have received considerable attention as a nonlinear optical material for ultrashort lasers and optical switch devices because of their attractive features such as ultrafast saturable absorption (SA) effects with a recovery time of faster than 1 ps. The SA wavelength depends on the tube diameter. We previously reported an SWNT polymer material that used polymethylmethacrylate (PMMA) and applied it to a passively mode-locked Er fiber laser for 171 fs pulse generation at 1.55 μm. In this report, we describe a mode-locked Yb-doped fiber laser for femtosecond pulse generation at 1.1 μm realized by using an SWNT/PMMA wafer in the cavity. By optimizing the cavity configuration as a dispersion-managed soliton laser, we obtained a 543 fs, 15.1 MHz pulse train.

  63. Increase of Output Power of Passively Mode-Locked Fiber Laser with a SWNT

    ONO Takato, HORI Yuichiro, YOSHIDA Masato, HIROOKA Toshihiko, NAKAZAWA Masataka, MATA Junji, TSUKAMOTO Jun

    Technical report of IEICE. OPE　112　(183)　87-90　2012/08/16

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    We have demonstrated a passively mode-locked fiber laser with SWNT-based saturable absorbers made by uniformly dispersing SWNTs into polymer such as poly methyl methacrylate, or by depositing SWNTs on the optical fiber end. However, the output power of the lasers is limited to less than 10 mW due to relatively low tolerance to optical damage of these SWNT-based saturable absorbers. In this work, we fabricated a SWNT saturable absorber with a substantial increase in the optical damage threshold by sealing SWNT with siloxane which has a high heat resistance. By installing this saturable absorber in a passively mode-locked fiber laser, a 31 mW, 280 fs ultrashort pulse was successfully generated.

  64. 1.07μm passively mode-locked ytterbium-doped fiber laser with SWNT/PMMA saturable absorber

    YOSHIDA Masato, HORI Yuichiro, HIROOKA Toshihiko, NAKAZAWA Masataka

    Technical report of IEICE. LQE　112　(184)　83-86　2012/08/16

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    Single-wall carbon nanotubes (SWNT) have received considerable attention as a nonlinear optical material for ultrashort lasers and optical switch devices because of their attractive features such as ultrafast saturable absorption (SA) effects with a recovery time of faster than 1 ps. The SA wavelength depends on the tube diameter. We previously reported an SWNT polymer material that used polymethylmethacrylate (PMMA) and applied it to a passively mode-locked Er fiber laser for 171 fs pulse generation at 1.55 μm. In this report, we describe a mode-locked Yb-doped fiber laser for femtosecond pulse generation at 1.1 μm realized by using an SWNT/PMMA wafer in the cavity. By optimizing the cavity configuration as a dispersion-managed soliton laser, we obtained a 543 fs, 15.1 MHz pulse train.

  65. Increase of Output Power of Passively Mode-Locked Fiber Laser with a SWNT

    ONO Takato, HORI Yuichiro, YOSHIDA Masato, HIROOKA Toshihiko, NAKAZAWA Masataka, MATA Junji, TSUKAMOTO Jun

    Technical report of IEICE. LQE　112　(184)　87-90　2012/08/16

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    We have demonstrated a passively mode-locked fiber laser with SWNT-based saturable absorbers made by uniformly dispersing SWNTs into polymer such as poly methyl methacrylate, or by depositing SWNTs on the optical fiber end. However, the output power of the lasers is limited to less than 10 mW due to relatively low tolerance to optical damage of these SWNT-based saturable absorbers. In this work, we fabricated a SWNT saturable absorber with a substantial increase in the optical damage threshold by sealing SWNT with siloxane which has a high heat resistance. By installing this saturable absorber in a passively mode-locked fiber laser, a 31 mW, 280 fs ultrashort pulse was successfully generated.

  66. 32 RZ/QAM coherent optical transmission employing an RZ-CW conversion technique

    KASAI Keisuke, OTUYA David Odeke, YOSHIDA Masato, HIROOKA Toshihiko, NAKAZAWA Masataka

    Technical report of IEICE. OCS　112　(152)　13-18　2012/07/19

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    Coherent optical time division multiplexing (OTDM) transmission with a multi-level modulation format has attracted a lot of attention as a ultra-high speed and highly spectral-efficient optical transmission system. However, in the conventional coherent OTDM, it is difficult to demodulate an ultra-high speed, multi-level RZ data signal with a high signal to noise ratio due to input optical power limitation of coherent detection circuits. Recently, we proposed a demodulation scheme by using an RZ-CW conversion scheme in a coherent receiver, in which the transmitted coherent RZ data are OTDM demultiplexed and converted into a data signal on a CW carrier. In this paper, we demonstrate an advantage of the scheme with 10 Gsymbol/s, 4- and 8-OTDM 32 RZ/QAM demodulation experiments. Furthermore, we have successfully transmitted a polarization multiplexed, 10 Gsymbol/s, 32 RZ/QAM (800 Git/s) data signal over 225 km by using this conversion scheme.

  67. Demultiplexing of 160Gbit/s OTDM signal using a nonlinear optical loop mirror at 1.1μm

    KOIZUMI Kengo, HIROOKA Toshihiko, YOSHIDA Masato, NAKAZAWA Masataka

    Technical report of IEICE. OCS　112　(86)　47-52　2012/06/14

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    With the increasing demand for ultrahigh capacity optical networks, it has been increasingly important to exploit new transmission bandwidths beyond the 1.55 and 1.31μm bands. The 1.1μm region is expected to provide an ultrawide transmission band because a wideband ytterbium (Yb)-doped fiber amplifiers (YDFA) are available. In this talk, we describe a multiplexer and demultiplexer using a nonlinear optical loop mirror (NOLM), and demonstrate the generation and demultiplexing of a 160 Gbit/s optical time-division multiplexed (OTDM) signal using a 10 GHz mode-locked Yb fiber laser in the 1.1μm wavelength region.

  68. Depolarization-Induced Crosstalk in Polarization-Multiplexed Transmission and Its Impact on Ultrahigh-Speed Optical Transmission

    HIROOKA Toshihiko, HARAKO Koudai, GUAN Pengyu, NAKAZAWA Masataka

    Technical report of IEICE. OCS　112　(42)　1-4　2012/05/11

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    Ultrashort optical pulses such as used in a single-channel Terabit/s OTDM transmission suffers from significant transmission impairments due to second-order PMD, i.e., signal depolarization due to frequency dependence of a principal state of polarization, even when the first-order PMD is completely compensated. In particular, in polarization-multiplexed transmission, depolarization leads to a complicated form of inter-polarization crosstalk, which prevents one from complete separation of the two channels. In this paper, we shall present an analytical expression and experimental demonstration of depolarization-induced crosstalk in polarization-multiplexed transmission caused by second-order PMD. It is found that the crosstalk depends on the fourth power of the bandwidth and the square of distance.

  69. B-10-34 Ultrahigh-speed orthogonal TDM transmission with an optical Nyquist pulse train

    Nakazawa Masataka, Hirooka Toshihiko, Ruan Peng, Guan Pengyu

    Proceedings of the IEICE General Conference　2012　(2)　357-357　2012/03/06

    Publisher: The Institute of Electronics, Information and Communication Engineers

  70. B-10-54 Single-channel 800 Gbit/s, 32 RZ/QAM coherent transmission employing an RZ-CW conversion technique

    Kasai Keisuke, Odeke Otuya David, Yoshida Masato, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2012　(2)　377-377　2012/03/06

    Publisher: The Institute of Electronics, Information and Communication Engineers

  71. B-10-70 Demultiplexing of 160 Gbit/s OTDM signal using a nonlinear optical loop mirror at 1.1μm

    Koizumi Kengo, Hirooka Toshihiko, Yoshida Masato, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2012　(2)　393-393　2012/03/06

    Publisher: The Institute of Electronics, Information and Communication Engineers

  72. B-10-49 Comparison between Polarization-Multiplexed DPSK and Single-Polarization DQPSK in 1.28Tbit/s/ch-525 km Transmission

    Tomiyama Yutaro, Harako Koudai, Guan Pengyu, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2011　(2)　262-262　2011/08/30

    Publisher: The Institute of Electronics, Information and Communication Engineers

  73. BI-7-8 512 QAM ultra-multilevel digital coherent optical transmission

    Koizumi Yuki, Toyoda Kazushi, Yoshida Masato, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2011　(1)　"SS-67"-"SS-68"　2011/08/30

    Publisher: The Institute of Electronics, Information and Communication Engineers

  74. B-10-27 PMD-Induced Crosstalk in the Presence of PDL in a Polarization-Multiplexed Ultrahigh-Speed Transmission

    Hirooka Toshihiko, Hirano Toshiyuki, Guan Pengyu, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2011　(2)　336-336　2011/02/28

    Publisher: The Institute of Electronics, Information and Communication Engineers

  75. B-10-82 640 Gbit/s Clock Recovery Using Time-Domain Optical Fourier Transformation and Narrow-Band Optical Filter

    Guan Pengyu, Mulvad Hans Christian Hansen, Kasai Keisuke, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2011　(2)　391-391　2011/02/28

    Publisher: The Institute of Electronics, Information and Communication Engineers

  76. Performance improvement of 10Gsymbol/s, 64 QAM coherent optical transmission by using back propagation method of nonlinear Schrodinger equation

    TOYODA Kazushi, OKAMOTO Seiji, OMIYA Tatsunori, YOSHIDA Masato, HIROOKA Toshihiko, NAKAZAWA Masataka

    IEICE technical report　110　(392)　67-72　2011/01/20

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    We have demonstrated 64〜512 QAM coherent optical transmission using a C_2H_2 frequency-stabilized fiber laser and an OPLL circuit. In such a ultra multi-level transmission, compensation for impairments due to fiber dispersion and nonlinearity plays a very important role. As a highly precise compensation scheme, a back propagation method of the nonlinear Schrodinger equation has been proposed. We applied this scheme to a single-polarization, 10 Gsymbol/s, 64 QAM transmission and demonstrated the impairment compensation both numerically and experimentally.

  77. B-10-79 Performance improvement of 10 Gsymbol/s, 64QAM coherent optical transmission by using back propagation method of nonlinear Schrodinger equation

    Toyoda Kazushi, Okamoto Seiji, Omiya Tatsunori, Yoshida Masato, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2010　(2)　266-266　2010/08/31

    Publisher: The Institute of Electronics, Information and Communication Engineers

  78. Single-channel 400Gbit/s, OTDM-32 RZ/QAM coherent transmission over 225km

    KASAI Keisuke, OMIYA Tatsunori, GUAN Pengyu, YOSHIDA Masato, HIROOKA Toshihiko, NAKAZAWA Masataka

    IEICE technical report　110　(94)　1-6　2010/06/17

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    Coherent optical time division multiplexing (OTDM) transmission with a multi-level modulation format based on digital signal processing (DSP) has attracted a lot of attention with a view to expanding the capacity per channel of wavelength division multiplexing (WDM) transmission systems. This transmission system can overcome the speed and bandwidth limitations of electrical components such as A/D and D/A converters and realize ultrahigh-speed coherent transmission by using a multi-level amplitude and phase-modulated coherent RZ pulse and the OTDM. However, in a conventional coherent OTDM system, the optical phase between an RZ data pulse and a local oscillator are not phase-locked. Therefore, it is difficult to realize a coherent OTDM transmission with high multiplicity. In this work, we demonstrated a multi-level coherent OTDM transmission with a high-precision optical phase-locked loop (OPLL) technique by using optical comb generation circuits. 400 Gbit/s data (polarization-multiplexed, 10 Gsymbol/s, 4-OTDM 32 RZ/QAM) were successfully transmitted over 225 km with a bit error rate performance below the forward error correction (FEC) limit. We also realized a 320 Gbit/s-450 km transmission with an OTDM 16 RZ/QAM scheme.

  79. B-10-89 640Gbit/s/channel-525km single-polarization DPSK transmission with ultrafast time-domain optical Fourier transformation circuit

    Hirano Toshiyuki, Guan Pengyu, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2010　(2)　427-427　2010/03/02

    Publisher: The Institute of Electronics, Information and Communication Engineers

  80. B-10-62 Optical phase-locked loop for coherent OTDM transmission with an optical comb technique

    Yoshida Masato, Kasai Keisuke, Omiya Tatsunori, Guan Pengyu, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2010　(2)　400-400　2010/03/02

    Publisher: The Institute of Electronics, Information and Communication Engineers

  81. B-10-82 Single-channel 400Gbit/s, OTDM-32 RZ/QAM coherent transmission over 225 km

    Kasai Keisuke, Omiya Tatsunori, Guan Pengyu, Yoshida Masato, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2010　(2)　420-420　2010/03/02

    Publisher: The Institute of Electronics, Information and Communication Engineers

  82. B-10-36 320 Gbit/s/ch WDM Transmission over 525 km Using Time-domain Optical Fourier Transformation

    Guan Pengyu, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2009　(2)　216-216　2009/09/01

    Publisher: The Institute of Electronics, Information and Communication Engineers

  83. B-10-81 160 Gbit/s×8 channel-525 km WDM transmission using time-domain optical Fourier transformation

    Guan Pengyu, Okazaki Masatada, Hirano Toshiyuki, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2009　(2)　400-400　2009/03/04

    Publisher: The Institute of Electronics, Information and Communication Engineers

  84. B-10-77 10 Gbit/s photonic crystal fiber transmission with a l.1μm directly-modulated VCSEL

    Koizumi Kengo, Hirooka Toshihiko, Yoshida Masato, Nakazawa Masataka

    Proceedings of the IEICE General Conference　396-396　2009

    Publisher: The Institute of Electronics, Information and Communication Engineers

  85. 次世代光通信基盤技術の展望

    中沢正隆, 廣岡俊彦

    ケミカルエンジニヤリング　54　(1)　51-57　2009/01

  86. B-10-73 All-optical 40 GHz time-domain Fourier transformation using XPM with an optical parabolic pulse

    Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2008　(2)　356-356　2008/03/05

    Publisher: The Institute of Electronics, Information and Communication Engineers

  87. モード同期ファイバーレーザーと超高速光通信 (特集 最近の光周波数制御技術とその応用)

    中沢 正隆, 廣岡 俊彦

    光技術コンタクト　45　(11)　579-586　2007/11

    Publisher: 日本オプトメカトロニクス協会

    ISSN： 0913-7289

  88. B-10-48 160 Gbit/s-1000 km Straight-line DPSK Transmission with Time-domain Optical Fourier Transmission

    Okazaki Masatada, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2007　(2)　242-242　2007/08/29

    Publisher: The Institute of Electronics, Information and Communication Engineers

  89. Photonic crystal fiber transmission with an 850nm VCSEL

    HIROOKA Toshihiko, HASEGAWA Hideaki, OIKAWA Yosuke, NAKAZAWA Masataka, SUZUKI Kenya, INOUE Yasuyuki

    IEICE technical report　107　(34)　1-6　2007/05/04

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    Recently, a photonic crystal fiber (PCF), which has a core region surrounded by multiple air holes, has received a lot of attention because of its new characteristics such as endlessly single-mode operation and arbitrary dispersion control. By combining PCF with inexpensive and high-speed optical devices such as VCSEL and Si-APD, we can construct low-cost and high-speed communication systems in the 800nm region such as 10-40 Gbit/s Ethernet. In this paper, we describe key technologies for 800nm high-speed transmission such as low-dispersion PCF and single-mode VCSEL. Then we describe the demonstration of a single-channel 10Gbit/s and 4×2.5Gbit/s WDM transmission with a directly modulated VCSEL. We also report a single-channel 40Gbit/s and 4×10Gbit/s WDM transmission through the PCF by employing an externally modulated VCSEL. These results indicate that simple, inexpensive and high-speed transmission over short distances such as LAN and FTTH appears to be feasible by combining these devices.

  90. B-10-44 40 Gb/s-2 km photonic crystal fiber transmission with an 850 nm single-mode VCSEL

    Hasegawa Hideaki, Oikawa Yosuke, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2007　(2)　383-383　2007/03/07

    Publisher: The Institute of Electronics, Information and Communication Engineers

  91. B-10-43 10 Gbit/s (4 x 2.5 Gbit/s) photonic crystal fiber transmission with direct modulation of 850 nm VCSELs

    Oikawa Yosuke, Hasegawa Hideaki, Hirooka Toshihiko, Nakazawa Masataka, Suzuki Kenya, Inoue Yasuyuki

    Proceedings of the IEICE General Conference　2007　(2)　382-382　2007/03/07

    Publisher: The Institute of Electronics, Information and Communication Engineers

  92. B-10-67 Effect of time-domain optical Fourier transformation on 160 Gbit/s DPSK transmission

    Hirooka Toshihiko, Osawa Kou, Okazaki Masatada, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2007　(2)　406-406　2007/03/07

    Publisher: The Institute of Electronics, Information and Communication Engineers

  93. B-10-23 40 Gbit/s (4×10 Gbit/s) over 5km photonic crystal fiber transmission using VCSELs and AWG at 850nm

    Oikawa Yosuke, Hasegawa Hideaki, Suzuki Kenya, Inoue Yasuyuki, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2006　(2)　217-217　2006/09/07

    Publisher: The Institute of Electronics, Information and Communication Engineers

  94. C-4-13 40GHz bright and dark parabolic optical pulse generation using a picosecond optical pulse source and a 64 channel AWG

    Hirooka Toshihiko, Osawa Kou, Nakazawa Masataka, Okamoto Katsunari

    Proceedings of the Society Conference of IEICE　2006　(1)　227-227　2006/09/07

    Publisher: The Institute of Electronics, Information and Communication Engineers

  95. B-10-64 Performance comparison of SMZ and EA type 40GHz optical DEMUX devices in 160Gbit/s OTDM transmission

    Osawa Kou, Kumakura Takashi, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2006　(2)　258-258　2006/09/07

    Publisher: The Institute of Electronics, Information and Communication Engineers

  96. Comparison of optical demultiplexing using SMZ and EA modulator in 160Gbit/s-500km OTDM transmission

    HIROOKA Toshihiko, KUMAKURA Takashi, OSAWA Kou, NAKAZAWA Masataka

    IEICE technical report　106　(211)　33-38　2006/08/17

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    Optical time division multiplexing (OTDM) enables ultrahigh-speed transmission at a single wavelength with a bit rate beyond the limit of electrical signal processing. One of the key technologies for OTDM is an optical demultiplexer, which selects a low bit-rate signal from a high-speed OTDM data sequence at a receiver. In this paper, we compare two types of demultiplexers, one with a symmetric Mach-Zehnder (SMZ) switch and the other with an electro-absorption modulator (EAM), when used for 160Gbit/s (4×40Gbit/s) OTDM transmission over 500km. By combining the SMZ switch with a time-domain optical Fourier transmformation technique, we succeeded in obtaining slightly better bit-error rate (BER) performance than with the EAM.

  97. 40Gbit/s (4x10Gbit/s)-3km WDM transmission using 850nm VCSEL, AWG, and PCF

    OIKAWA Yosuke, HASEGAWA Hideaki, HIROOKA Toshihiko, YOSHIDA Masato, NAKAZAWA Masataka, SUZUKI Kenya, INOUE Yasuyuki

    IEICE technical report　106　(211)　27-32　2006/08/17

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    Recently, a photonic crystal fiber (PCF), which has a core region surrounded by multiple air holes, has received a lot of attention because of its new characteristics such as endlessly single-mode operation and arbitrary dispersion control. By combining a VCSEL, a Si-APD, and a PCF we can construct inexpensive and high-speed communication systems such as 10-40Gbit/s Ethernet. In this paper, we report the first 10Gbit/s x 4 channel WDM transmission over 3km at 850nm using a single-mode PCF without power penalty. We used a special arrayed waveguide grating (AWG) operating at 850nm as a multiplexer and a demultiplexer.

  98. Linewidth broadening in high-speed optical comb transmission using a picosecond mode-locked laser

    OSAWA Kou, HIROOKA Toshihiko, YOSHIDA Masato, NAKAZAWA Masataka

    IEICE technical report　106　(211)　63-68　2006/08/17

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    An optical pulse train generated from a mode-locked laser has neatly repetitive longitudinal modes in the frequency domain. Since the interval between adjacent modes is defined by the repetition frequency of the laser and each mode has a narrow linewidth with a high SN ratio, the modes can be used for highly accurate optical frequency measurement. Recently, the delivery of such optical frequency standards through optical fiber networks has become an important subject. When we transmit longitudinal modes through an optical fiber network, it is very important to investigate the deformation in the power spectrum of the modes that occurs during the transmission. In this paper, we report the spectrum deformation of the longitudinal mode that occurs during long-haul transmission through dispersion-shifted fiber. We used a 10GHz mode-locked fiber laser with a linewidth as narrow as 1kHz as the signal source. As a result, we found that the deformation of the longitudinal mode power spectrum occurs mainly at the tail of the spectrum and the linewidth broadening increases in proportion to the transmission distance. The main reason for the linewidth broadening in the present experiment was the phase fluctuation of the optical fiber caused by temperature fluctuation or vibration.

  99. B-10-68 160 Gbit/s-524km OTDM Transmission Using Time-domain Optical Fourier Transformation

    Hagiuda Ken-ichi, Kumakura Takashi, Osawa Kou, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2006　(2)　388-388　2006/03/08

    Publisher: The Institute of Electronics, Information and Communication Engineers

  100. B-10-81 10Gb/s-5km transmission at 850nm using a photonic crystal fiber, VCSEL, and Si-APD

    Hasegawa Hideaki, Oikawa Yosuke, Hirooka Toshihiko, Yoshida Masato, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2006　(2)　401-401　2006/03/08

    Publisher: The Institute of Electronics, Information and Communication Engineers

  101. Observation of Optimum Air-Hole Tapering of Splicing between a Conventional Fiber and a Photonic Crystal Fiber and Analysis of Reduction of Fresnel Reflection

    HASEGAWA Hideaki, KIKEGAWA Manabu, YOSHIDA Masato, HIROOKA Toshihiko, NAKAZAWA Masataka

    The IEICE transactions on electronics C　88　(10)　779-787　2005/10/01

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 1345-2827

  102. B-10-72 ABCD matrix formalism for distortion-free transmission using time-domain optical Fourier transformation

    Nakazawa Masataka, Hirooka Toshihiko

    Proceedings of the Society Conference of IEICE　2005　(2)　290-290　2005/09/07

    Publisher: The Institute of Electronics, Information and Communication Engineers

  103. B-10-73 Derivation of analytical expression for third-order dispersion elimination using time-domain optical Fourier transformation

    Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2005　(2)　291-291　2005/09/07

    Publisher: The Institute of Electronics, Information and Communication Engineers

  104. C-3-107 Fabrication of a zero-dispersion, dispersion-flattened photonic crystal fiber in the 800 nm region

    Hasegawa Hideaki, Oikawa Yosuke, Hirooka Toshihiko, Yoshida Masato, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2005　(1)　251-251　2005/09/07

    Publisher: The Institute of Electronics, Information and Communication Engineers

  105. A New Method for Optimum Dispersion Designing of Zero-Dispersion and Dispersion-Flattened Photonic Crystal Fibers

    HASEGAWA Hideaki, HIROOKA Toshihiko, NAKAZAWA Masataka

    The IEICE transactions on electronics C　88　(7)　519-527　2005/07/01

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 1345-2827

  106. B-10-69 Theoretical study on elimination of waveform distortion using time-domain optical Fourier transformation

    Nakazawa Masataka, Hirooka Toshihiko

    Proceedings of the IEICE General Conference　2005　(2)　359-359　2005/03/07

    Publisher: The Institute of Electronics, Information and Communication Engineers

  107. B-10-68 Proposal of ultrahigh-speed distortion-free transmission using all-optical time-domain Fourier transformation

    Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2005　(2)　358-358　2005/03/07

    Publisher: The Institute of Electronics, Information and Communication Engineers

  108. C-3-76 Broadband dispersion measurement of a photonic crystal fiber with pico-second streak camera and SC light

    Hasegawa Hideaki, Oikawa Yousuke, Yoshida Masato, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2005　(1)　246-246　2005/03/07

    Publisher: The Institute of Electronics, Information and Communication Engineers

  109. Effect of stimulated Brillouin scattering in generation of an ultrahigh-speed femtosecond pulse train using a dispersion-decreasing fiber

    HAGIUDA Ken-ichi, HIROOKA Toshihiko, NAKAZAWA Masataka

    326　13-18　2004/08/26

  110. Ultrahigh-speed parabolic pulse generation for time-domain optical Fourier transformation

    HIROOKA Toshihiko, NAKAZAWA Masataka

    326　117-122　2004/08/26

  111. B-10-118 Distortion-free transmission of ultrashort optical pulses using optical Fourier transformation

    Hirooka Toshihiko, Nakazawa Masataka, Futami Fumio, Watanabe Shigeki

    Proceedings of the IEICE General Conference　2004　(2)　489-489　2004/03/08

    Publisher: The Institute of Electronics, Information and Communication Engineers

  112. C-3-138 A method for optimizing dispersion characteristics of photonic crystal fibers

    Hasegawa Hideaki, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2004　(1)　312-312　2004/03/08

    Publisher: The Institute of Electronics, Information and Communication Engineers

  113. C-3-144 Splicing characteristics between a photonic crystal fiber and a conventional fiber

    Kikegawa Manabu, Hasegawa Hideaki, Yoshida Masato, Hirooka Toshihiko, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2004　(1)　318-318　2004/03/08

    Publisher: The Institute of Electronics, Information and Communication Engineers

  114. C-4-1 Stimulated Brillouin Scattering in DDF soliton compression of an ultrahigh-speed optical pulse train

    Ono Shimpei, Hirooka Toshihiko, Yoshida Masato, Nakazawa Masataka

    Proceedings of the IEICE General Conference　2004　(1)　329-329　2004/03/08

    Publisher: The Institute of Electronics, Information and Communication Engineers

  115. FDTD Analysis of Fresnel Reflection at a Splice between a Photonic Crystal Fiber and a Conventional Fiber

    Hirooka Toshihiko, Hori Yusuke, Hasegawa Hideaki, Yoshida Masato, Nakazawa Masataka

    Proceedings of the Society Conference of IEICE　2003　(1)　214-214　2003/09/10

    Publisher: The Institute of Electronics, Information and Communication Engineers

  116. Observation of an optimum air-hole tapering for splicing between a conventional fiber and a photonic crystal fiber and the reduction of Fresnel reflection

    KIKEGAWA Manabu, HASEGAWA Hideaki, YOSHIDA Masato, HIROOKA Toshihiko, NAKAZAWA Masataka

    Technical report of IEICE. OCS　103　(255)　51-56　2003/08/21

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    We have already reported about an observation of a huge Fresnel reflection at a splicing point between a photonic crystal fiber (PCF) and a conventional fiber. This was caused by the difference of the refractive index in the claddings, which leads to a serious problem when utilizing PCF in optical communications. In this paper, the splicing characteristics between a PCF and a conventional fiber were measured in detail, and a splicing condition for suppressing the Fresnel reflection to below the Rayleigh scattering level was clarified. We also measured the cross-sectional structures of PCF near the splicing point by SEM, and a relation between reduction of the Fresnel reflection and air-hole form in the cladding of PCF was discussed.

  117. Gaussian and Sech Approximation of a Mode Field in Photonic Crystal Fibers

    HIROOKA Toshihiko, HORI Yusuke, NAKAZAWA Masataka

    Technical report of IEICE. OFT　103　(257)　57-62　2003/08/14

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

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    Mode field distribution in the cladding region of photonic crystal fibers (PCF) depends strongly on the wavelength or the cladding structure. In this report, we formulate the least square approximation of the electrical field distribution of the fundamental mode (HEn mode) in PCF by a Gaussian and a hyperbolic-secant (sech) function. The analysis shows that the shape of the mode field varies with the ratio of a hole diameter d and a pitch A. The mode field is found to be approximated by a Gaussian function for large d/Λ values (i.e., for strongly guiding structure) as in step-index fibers, and by a sech function for small d/Λ values (for weakly guiding structure).

  118. Observation of an optimum air-hole tapering for splicing between a conventional fiber and a photonic crystal fiber and the reduction of Fresnel reflection

    KIKEGAWA Manabu, HASEGAWA Hideaki, YOSHIDA Masato, HIROOKA Toshihiko, NAKAZAWA Masataka

    Technical report of IEICE. OFT　103　(257)　51-56　2003/08/14

    Publisher: The Institute of Electronics, Information and Communication Engineers

    ISSN： 0913-5685

    More details Close

    We have already reported about an observation of a huge Fresnel reflection at a splicing point between a photonic crystal fiber (PCF) and a conventional fiber. This was caused by the difference of the refractive index in the claddings, which leads to a serious problem when utilizing PCF in optical communications. In this paper, the splicing characteristics between a PCF and a conventional fiber were measured in detail, and a splicing condition for suppressing the Fresnel reflection to below the Rayleigh scattering level was clarified. We also measured the cross-sectional structures of PCF near the splicing point by SEM, and a relation between reduction of the Fresnel reflection and air-hole form in the cladding of PCF was discussed.

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Books and Other Publications 1

  1. フォトニクス基礎

    伊藤弘昌

    コロナ社　2009/11

Research Projects 7

  1. 振幅・位相および時間情報を用いた３次元光秘匿通信技術の研究開発

    吉田 真人, 廣岡 俊彦, 葛西 恵介

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 基盤研究(A)

    Institution: 東北大学

    2021/04/05 - 2025/03/31

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    初年度は、これまでに開発してきた光の位相と振幅を用いた2次元物理暗号へ、新たに時間軸におけるデータの拡散動作を導入した3次元光秘匿通信の動作原理を実証した。具体的には、送信機として任意波形生成装置を使用し、受信器としてデジタルオシロスコープを用いた単一チャネルのオフライン伝送実験の結果をもとに、時間軸のデータ拡散動作を追加することによる安全性の向上効果を検証した。その結果、8ビット以上の乱数を用いた時間拡散を利用することにより、盗聴者が1シンボル分の正しい情報を得るために必要な信号の受信回数を1桁以上高められることを明らかにした。これは暗号化に用いる信号の多値度を4倍（2ビット）高めることに相当する。言い換えると、一定の安全性を確保することを考えた場合に、時間領域の拡散効果を利用することにより暗号化信号の多値度を2ビットだけ下げることができ、より汎用性の高い電子部品（D/A、A/D変換器）を送受信装置に利用することが可能となる。このように提案する光秘匿通信方式の実用性を高められることを明らかにした。 また本年度は、上述したオフライン伝送実験の成果をもとに、リアルタイム動作を実現するためのFPGA（Field Programmable Gate Array）回路の作製に着手した。具体的には8ビットの乱数列生成器を追加し、それを用いて申請書で提案した2種類の時間拡散動作（方式１：ダミー信号を利用する方式、方式２：ダミー信号は用いず、暗号化データの順序を時間軸上で入れ替える）を実現するためのFPGA回路を設計した。

  2. 多機能なコヒーレントナイキストパルスの提案とそれを用いた超高速・高効率光伝送技術

    中沢 正隆, 廣岡 俊彦, 吉田 真人, 葛西 恵介

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 特別推進研究

    Institution: 東北大学

    2014 - 2018

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    本年度はナイキストパルス伝送の高速・大容量化ならびに周波数利用効率(SE : Spectral Efficiency)向上への最終的な取り組みとして、(a)ノンコヒーレントナイキストパルスを用いた単一チャネル10Tbit/s伝送の実現、(b)波長多重ナイキストパルス伝送、ならびに(c)コヒーレントナイキストパルス伝送の単一チャネル15Tbit/sへの高速化・高SE化、の3つに取り組んだ。 (a)に関しては、2.56Tsymbol/sのシンボルレートで単一チャネル10.2Tbit/sの超高速伝送を2.5～3.7bit/s/HzのSEで実現した。10Tbit/sへの高速化にあたり、ノンコヒーレントナイキストパルスの340fsへの超短パルス化、4次分散まで考慮した高次分散補償、ならびに非線形ファイバループミラー(NOLM : Nonlinear Optical Loop Mirror)を用いたゲート幅230fsの超高速光多重分離を実現した。これらの技術を結集し、単一チャネル10.2Tbit/s信号の225km伝送(SE : 3.7bit/s/Hz)および300km伝送(SE : 2.5bit/s/Hz)を達成した。 次に(b)に関しては、ナイキストパルスの波長分割多重(WDM : Wavelength Division Multiplexing)への応用を目指して、1チャネルあたり1.28Tbit/sの超高速WDM伝送システムを構築した。この際、光通信用波長帯(Cバンド)で18Tbit/sのWDM信号を僅か14チャネルで生成することにより、1.28Tbits×14波WDM伝送を3.7bit/s/HzのSEで実現した。 (c)に関しては、最終目標であるコヒーレントナイキストパルスを用いた単一チャネル15.4Tbit/s、SE=8.3bit/s/Hzの超高速・高効率伝送に世界で初めて成功した。具体的には、コヒーレントパルスのシンボルレートを1.28Tsymbol/sまで高速化し、64QAM(Quadrature Amplitude Modulation)方式により単一チャネルで10Tbit/sを凌駕する究極的なコヒーレント超高速伝送を実現している。その際、ホモダイン検波回路における自己ビート成分の低減、および多重分離に関与しないトリビュータリを抑制するための光ゲート回路の導入により、ナイキストパルスの高OSNR化を図っている。これらの要素技術により、単一チャンネル15.4Tbit/s-150km超高速コヒーレントナイキストパルス伝送を8.3bit/s/Hzという極めて高いSEで達成した。 以上により、ナイキストパルスが高速性と高SE化の両面で極めて優れた伝送性能を有する究極的な光パルスであることを実証することに成功した。

  3. GHz mode-locked pulse laser with simultaneously stabilized optical frequency and repetition rate and its applications

    NAKAZAWA MASATAKA, YOSHIDA Masato

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (S)

    Institution: Tohoku University

    2009/05/11 - 2014/03/31

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    We have demonstrated for the first time a mode-locked pulse laser with simultaneo-usly stabilized optical frequency and repetition rate by using a Cs atomic resonance and an acetylene mol-ecular absorption line, respectively. We also successfully demonstrated a 440 fs short pulse generation byemploying a saturable absorber in the laser cavity for narrowing the pulse width. Furthermore,we applied apulse source based on a frequency stabilized CW laser to coherent optical pulse transmission, and we have successfully demonstrated for the first time a 1.92 Tbit/s single channel transmission with 64 QAM signal.

  4. 超高速光パラボラパルスの発生と光伝送・信号処理への応用

    廣岡 俊彦

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 若手研究(S)

    Institution: 東北大学

    2009 - 2013

    More details Close

    本年度はまず、従来用いてきたアレイ導波路回折格子の代わりに、周波数分解能が1GHzの液晶型波長選択光スイッチを波形整形回路として新たに用いることにより、簡便で且つ高精度なパラボラ光パルスの発生に初めて成功した。従来の手法では光スペクトルの縦モードを1本ずつ分波し各々の強度と位相を制御していたのに対し、本回路は光スペクトルを液晶型の変調器で制御しており、液晶をシリコン基板上に形成することにより高い分解能を実現している。その結果、縦モードを分波することなくスペクトルを制御できるため、波形整形の自由度が飛躍的に向上している。さらに、強度変調の消光比も15 dB以上向上しており、波形の高精度化だけでなくS/Nも大幅に改善することに成功した。 また、パラボラ光パルスの新たな応用として、時間領域光フーリエ変換(OFT)を位相比較器として用いた超高速光信号のクロック抽出回路を提案した。この手法は、OFTを用いて高速の光パルス列を周波数軸上のスペクトル列に変換し、OFT回路中の位相変調ピークからのずれ量を狭帯域光フィルタを用いて検出している。これを誤差信号としてPLL制御を行なうことによりクロック信号を抽出している。実際に本手法を用いて、640 Gbit/s OTDM信号から40 GHzのクロック抽出を実証した。

  5. Research on 320 Gbit/s-500 km OTDM Transmission Technology

    HIROOKA Toshihiko

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Young Scientists (A)

    Institution: Tohoku University

    2007 - 2008

  6. Establishment of novel ultrahigh-speed distortion-free optical transmission technology using time-domain optical Fourier transformation

    NAKAZAWA Masataka, HIROOKA Toshihiko, YOSHIDA Masato

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Specially Promoted Research

    Institution: Tohoku University

    2004 - 2008

  7. 波長分割多重ソリトン方式によるネットワークに関する研究

    廣岡 俊彦

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 特別研究員奨励費

    Institution: 大阪大学

    1998 - 1999

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