TODA HIROYUKI
Faculty of Science and Engineering Department of Electronics
Professor
Last Updated :2019/09/19

Researcher Profile and Settings

Research Interests

  • Microwave photonics
  • Optical Fiber Communication
  • Radio on fiber
  • Optical Solitons
  • Wavelength-division multiplexing
  • Optical time-division multiplexing
  • Nonlinear optics
  • Optical modulators

Research Areas

  • Electrical and electronic engineering/Communication/Network engineering
  • Electrical and electronic engineering/Electron device/Electronic equipment

Research History

  • 1999- Engaged in research on Microwave Photonics
  • 1992- Engaged in research on optical fiber communication
  • 1990-1992 Engaged in research on nonlinear optical devices
  • 1984-1990 Engaged in research on Integrated-uptic devices

Academic & Professional Experience

  • Doshisha University, Associate Professor, 2005 - 2008
  • - Doshisha University, Professor, 2008
  • Osaka University, Assistant Professor, 1998 - 2005
  • Osaka University, Research Associate, 1996 - 1998
  • Osaka University, Research Associate, 1990 - 1996
  • Georgia Institute of Technology, Postdoctoral , 1990 - 1992
  • Fellowships of the Japan Society for the , 1989 - 1990
  • Fellow
  • Scientists
  • Promotion of Science for Japanese Junior

Education

  • Osaka University, Graduate School, Division of Engineering, Department of Electronic Engineering, 1989
  • Osaka University, Graduate School, Division of Engineering, Department of Electronic Engineering, 1986
  • Osaka University, Faculty of Engineering, Department of Electronic Engineering, 1984

Academic Degrees

  • Doctor of Engineering, Osaka University
  • Master of Engineering, Osaka University

Association Memberships

  • Laser Society of Japan
  • Japanse Society of Applied Physics - JSAP
  • Optical Society of America - OSA
  • Institute of Electronics
  • Information and Communication Engineers - IEICE
  • Institute of Electrical and Electronics Engineers - IEEE

Published Papers

  • Flexible generation of 28 Gbps PAM4 60 GHz/80 GHz radio over fiber signal by injection locking of direct multilevel modulated laser to spacing-tunable two-tone light
    Guo Wei Lu, Guo Wei Lu, Ruben S. Luís, Hiroyuki Toda, Jiabin Cui, Takahide Sakamoto, Hongxiang Wang, Yuefeng Ji, Naokatsu Yamamoto
    © 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement To meet the ever-increasing bandwidth demands in the future broadband wireless networks, the millimeter-wave (mm-wave) frequency region is being actively perused, owing to its broad bandwidth and high frequencies. In this paper, a photonic mm-wave system is proposed and experimentally demonstrated based on the injection locking of a direct multilevel modulated laser to a spacing-tunable two-tone light. Since the mm-wave frequency of the generated signal is locked to the frequency spacing of the injected two-tone light, it shows better frequency stabilization than the schemes based on two free-running lasers. Moreover, by simply tuning the tone spacing, the mm-wave frequency could be easily reconfigured, offering flexibility in the mm-wave signal generation. Instead of using complex and expensive optical modulators, the multilevel modulation on the mm-wave data carrier is implemented through the direct multilevel modulation of a laser and the injection locking. A 28 Gbps four-level pulse amplitude modulation (PAM4) is realized by biasing a 10 G-class laser at a current far from the threshold, providing a cost-effective and simple mm-wave generation scheme. In the experiment, a photonic approach to generating 28 Gbps PAM4 60 GHz/80 GHz mm-wave signals is experimentally demonstrated. A power penalty of less than 0.2 dB is observed for the filtered-out PAM4 signals with respect to the original PAM4. Besides, an ultra-low phase noise of up to −98 dBc/Hz is obtained for the mm-wave carriers after the injection locking. The proposed scheme possesses the flexibility and frequency stability of the mm-wave frequency, and also has low cost and implementation complexity., Optics Express, 2620603 - 20613, 06 Aug. 2018
  • Towards ultrasensitive optical links enabled by low-noise phase-sensitive amplifiers
    Z. Tong, C. Lundström, P. A. Andrekson, C. J. McKinstrie, M. Karlsson, D. J. Blessing, E. Tipsuwannakul, B. J. Puttnam, H. Toda, L. Grüner-Nielsen
    In principle, optical phase-sensitive amplifiers are known to be capable of realizing noiseless amplification, as well as improving the signal-to-noise-ratio of optical links by 3 dB compared to conventional, phase-insensitively amplified links. However, current state-of-the-art phase-sensitive amplifiers are still far from being practical, lacking, for example, significant noise performance improvement, broadband gain and modulation-format transparency. Here, we demonstrate experimentally, for the first time, an optical-fibre-based non-degenerate phase-sensitive amplifier link consisting of a phase-insensitive parametric copier followed by a phase-sensitive amplifier that provides broadband amplification, signal modulation-format independence, and nearly 6 dB link noise-figure improvement over conventional, erbium-doped fibre amplifier-based links. The PSA has a record-low 1.1 dB noise figure, and can be extended to work with multiple wavelength channels with modest system complexity. This concept can also be realized in other materials with third-order nonlinearities, and is useful in any attenuation-limited optical link. © 2011 Macmillan Publishers Limited. All rights reserved., Nature Photonics, 5(7)430 - 436, Jul. 2011
  • Reconfigurable dense wavelength-division-multiplexing millimeter-waveband radio-over-fiber access system technologies
    Toshiaki Kuri, Hiroyuki Toda, Juan Jose Vegas Olmos, Juan Jose Vegas Olmos, Ken Ichi Kitayama
    A reconfigurable dense wavelength-division-multiplexed (DWDM) access system for millimeter-waveband radio-over-fiber (RoF) is described. Focuses are on the enabling techniques such as optical-frequency-interleaved DWDM grid assignment, supercontinuum multi-wavelength light source, photonic upconversion for RoF signals, and optical path switching for dynamic channel allocation for wireless services. © 2006 IEEE., Journal of Lightwave Technology, 282247 - 2257, 16 Aug. 2010
  • Reconfigurable 2.5-Gb/s baseband and 60-GHz (155-Mb/s) millimeter-waveband radio-over-fiber (interleaving) access network
    J. J. Vegas Olmos, Toshiaki Kuri, Takahiro Sono, Kazunori Tamura, Hiroyuki Toda, Ken Ichi Kitayama
    In this paper, we propose a dynamic reconfigurable wavelength division multiplexed (WDM) millimeter-waveband radio-over-fiber (RoF) and baseband access network. We also demonstrate dynamic channel allocation capability of millimeter-waveband optical RoF and baseband signals in WDM access network using a supercontinuum (SC) light source, arrayed-waveguide gratings, and a reconfigurable optical crossconnect switch. The dynamic reconfigurable RoF and baseband network architecture is presented and its features are described. Two 155-Mb/s RoF channels and two 2.5-Gb/s baseband channels are effectively generated, transmitted through 25 km of fiber, switched, and then transmitted again through 2 km of fiber and detected with error-free operation (bit error rate < 10-9). The proposed architecture allows the RoF and baseband to coexist and is highly scalable, both in terms of channel counts and access point (AP) counts. © 2008 IEEE., Journal of Lightwave Technology, 26(15)2506 - 2512, Nov. 2008
  • Wireless and optical-integrated access network with peer-to-peer connection capability
    J. J. Vegas Olmos, Toshiaki Kuri, Takahiro Sono, Kazunori Tamura, Hiroyuki Toda, Ken Ichi Kitayama
    We show a bidirectional optical access network with dynamic channel allocation capability of decimeter-wave band optical radio-over-fiber (RoF) and baseband signals. The network can be configured enabling peer-to-peer connectivity, and is based on a simple access point (AP) unit. The proposed RoF architecture is highly scalable, both in terms of channels and APs. © 2008 IEEE., IEEE Photonics Technology Letters, 20(13)1127 - 1129, Jul. 2008
  • Novel demultiplexer for dense wavelength-division-multiplexed millimeter-wave-band radio-over-fiber systems with optical frequency interleaving technique
    Toshiaki Kuri, Hiroyuki Toda, Ken Ichi Kitayama
    We propose a simple demultiplexer for dense wavelength- division-multiplexed (DWDM) milllimeter-wave-band radio-over-fiber (RoF) systems that uses an optical-frequency-interleaving technique, which consists of only a 2 × N arrayed waveguide grating with an optical coupler. In the proposed demultiplexer, a suppression ratio of more than 25 dB against adjacent channels is experimentally obtained. The transmission performance of 12-channel DWDM 60-GHz-band RoF signals with 25-GHz channel spacing over 25- and 2-km standard single-mode fibers via the proposed demultiplexer achieves a bit-error rate of less than 10-9. © 2007 IEEE., IEEE Photonics Technology Letters, 192018 - 2020, 15 Dec. 2007
  • Special section on evolution of microwave and millimeter-wave photonics technology
    Yuichi Matsushima, Yuichi Matsushima, Yuichi Matsushima, Hiroyuki Toda, Kazi Sarwar Abedin, Koji Yasukawa, Tomohiro Akiyama, Tadao Nagatsuma, Tazuko Tomioka, Hiroshi Ito, Hiroyuki Sasai, Kazuhisa Haeiwa, Masahiro Tsuchiya, Masashi Hotta
    IEICE Transactions on Electronics, E90-C343 - 344, 01 Jan. 2007
  • Distributed PMD compensation experiment using polarizers
    Hiroyuki Toda, Masaki Nara, Masaki Nara, Masayuki Matsumoto, Daniele Alzetta, Daniele Alzetta
    We experimentally demonstrated polarization-mode dispersion (PMD) compensation by distributing polarizers with only 1 degree of freedom (DOF) along the transmission line. The average power penalty was measured to be 0.4 dB by inserting four compensators, where average differential group delay was 47% of bit period. Copyright © 2007 The Institute of Electronics, Information and Communication Engineers., IEICE Transactions on Communications, E90-B3670 - 3672, Jan. 2007
  • Novel demultiplexer for dense wavelength division mutliplexed millimeter-wave-band radio-over-fiber systems with optical frequency interleaving technique
    Toshiaki Kuri, Hiroyuki Toda, Ken Ichi Kitayama
    IEEE Photonics Technology Letters, 19(24)2018 - 2020, 2007
  • Wavelength-division-multiplexed millimeter-waveband radio-on-fiber system using a supercontinuum light source
    Teppei Nakasyotani, Hiroyuki Toda, Hiroyuki Toda, Toshiaki Kuri, Toshiaki Kuri, Ken Ichi Kitayama, Ken Ichi Kitayama
    We propose to use a supercontinuum (SC) for a low-phase-noise multiwavelength light source in wavelength-division-multiplexing (WDM) millimeter-waveband (mm-waveband) radio-on-fiber (RoF) systems. We demonstrate the generation of low-phase-noise 60-GHz-band RoF signal. We also demonstrate the generation of two-channel WDM 60-GHz-band RoF signals and the transmission of the signals over a 25-km standard single-mode fiber (SMF) using photonic upconversion. The single multiwavelength light source can be shared with a number of users and simplifies the system configuration, which would allow the realization of high-reliability as well as low-cost RoF systems. Finally, the RoF network capacity with a single SC light source is estimated to be over 10 000 channels when the spectrum of the SC light source is fully utilized. © 2006 IEEE., Journal of Lightwave Technology, 24(1)404 - 410, Jan. 2006
  • DWDM millimeter-wave radio-on-fiber systems
    Hiroyuki Toda, Toshiaki Kuri, Ken Ichi Kitayama
    International Journal of Microwave and Optical Technology, 1(2)761 - 766, 2006
  • Compensation of Polarization Mode Dispersion for High-Speed Optical Fiber Transmission Systems
    TODA Hiroyuki, MATSUMOTO Masayuki, ALZETTA Daniele
    In optical fiber transmission systems, polarization mode dispersion (PMD), represents a severe source of degradation as the bit rate increases. In this paper, we review PMD compensation techniques performed in optical domain. We also report our experimental results on PMD compensation by distributing linear polarizers along the transmission line. Polarizers are used as PMD compensator elements with only 1 degree-of-freedom (DOF) which result in simple configuration and fast response. Even though the polarizers do not compensate 1 st-order PMD perfectly, Distributed 4 polarizers outperformed a 2-DOF polarizer-based PMD compensator placed at the optical receiver front-end., The Review of Laser Engineering, 一般社団法人 レーザー学会, レーザー研究, 33(2)95 - 99, Feb. 2005, Japanese
  • Compact dual-band antenna base station for simultaneously transmitting microwave and millimeter-wave signals in radio-on-fiber systems
    戸田 裕之
    IEEE LEOS Newsletter, 19(2)14 - 15, 2005
  • Demultiplexing using an arrayed-waveguide grating for frequency-interleaved DWDM millimeter-wave radio-on-fiber systems
    Hiroyuki Toda, Tsukasa Yamashita, Tsukasa Yamashita, Toshiaki Kuri, Ken Ichi Kitayama
    The frequency-interleaved dense- wavelength-division-multiplexing (DWDM) millimeter-wave (mm-wave) radio-on-fiber is an indispensable technique to improve the optical spectrum efficiency. We propose possible configurations of multiplexing and demultiplexing (DEMUX) schemes using an arrayed-waveguide grating (AWG) with two input and N output waveguides (N: total channel number). In this paper, we focus on the DEMUX scheme and experimentally demonstrate the DEMUX scheme using a commercially available AWG. In the experiment, 25-GHz-separated two-channel optical double sideband signals modulated by a 60-GHz millimeter-wave carrying a 156-Mb/s data are optically multiplexed by the frequency interleaving. The power penalty after DEMUX, which was due to interchannel interference, was less than 0.5 dB. We also made a transmission experiment over 25-km standard single-mode fiber (SMF). No noticeable power penalty in the received data due to chromatic dispersion of the transmission fiber was observed. This is because only the carrier and a sideband are detected in the proposed DEMUX scheme., Journal of Lightwave Technology, 21(8)1735 - 1741, Aug. 2003
  • Dense wavelength-division multiplexing millimeter-wave-band radio-on-fiber signal transmission with photonic downconversion
    Toshiaki Kuri, Hiroyuki Toda, Ken Ichi Kitayama
    Photonic downconversion (PDC) technique for dense wavelength division multiplexing (DWDM) millimeter-wave-band radio-on-fiber (ROF) uplink systems is investigated. The PDC technique is carried out for a lump of all uplink wavelength division multiplexing (WDM) ROF signals at a central station. Each channel is optically separated, photodetected, and demodulated individually without serious signal degradation due to the fiber dispersion effect. Error-free 25-GHz-spaced DWDM transmission and demultiplexing of two 60-GHz-band, 155-Mb/s differential phase-shift keying (DPSK) ROF signals over 25-km-long standard single-mode fiber (SMF) are experimentally demonstrated., Journal of Lightwave Technology, 21(6)1510 - 1517, Jun. 2003
  • Experimental demonstration of the compressed optical packet multiplexing scheme
    Akira Hasegawa, Hiroyuki Toda, Makoto Shikata, Yukihiro Ozeki, Tetsuyuki Suzaki, Yoshiyasu Ueno, Kazuhito Tajima
    Packet multiplexing has been proposed as a practical method in optical time-division multiplexing. One reasonable approach is to use a packet compression-expansion scheme at the node to match the transmission rate between the ultrafast backbone optical network and slower (electrical) networks. This scheme is superior to the conventional bit interleave scheme in that it does not require an ultrafast switch at the bit rate; instead, switching at the slower header bit rate and/or packet rate is sufficient. In contrast to the bit interleave, we call this scheme compressed optical packet multiplexing (COPM). Here we present an experimental demonstration of an all-optical COPM with use of a 155-Mbit/s video signal that is optically compressed into a 2.64-Gbit/s optical signal and optically expanded back to the original rate with a reasonable bit error rate. © 2002 Optical Society of America., Journal of Optical Networking, 1221 - 236, 01 Jan. 2002
  • Improvement of amplitude and phase margins in optical RZ receiver using nonlinearity in normal dispersion fiber: effect on the Gordon-Haus timing jitter
    戸田 裕之
    Trans. IEEJ, 122A(1)54 - 58, 2002
  • Experimental demonstration of compressed optical packet multiplexing scheme
    戸田 裕之
    OSA Journal of Optical Networking, 1(7)221 - 236, 2002
  • Improvement of amplitude and phase margins in an RZ optical receiver using Kerr nonlinearity in normal dispersion fiber
    Maoki Suzuki, Hiroyuki Toda, Anhui H. Liang, Akira Hasegawa
    In this letter, we propose a new return-to-zero (RZ) optical receiver to improve the amplitude and phase margins without increasing the intersymbol interference by utilizing Kerr nonlinearity in normal dispersion fiber. We employed this technique to a jitter-limited 10-Gb/s optical soliton transmission experiment at 16 000 km in a sliding frequency recirculating loop. The amplitude and phase margins obtained with the proposed method were 67% and 18% wider than that with the conventional RZ receiver using a 7.5-GHz low-pass filter., IEEE Photonics Technology Letters, 13(11)1248 - 1250, Nov. 2001
  • Optical packet compressor based on a fiber delay loop
    Hiroyuki Toda, Fumitoshi Nakada, Maoki Suzuki, Akira Hasegawa
    We propose an optical packet compressor based on a fiber delay loop and demonstrate its feasibility for an all optical inter-local area network (LAN) TDM network. The proposed scheme requires only a few devices for compression operation and only one delay to obtain the desired compression ratio. The calculated optical signal-to-noise ratio of the compressed packet with 1-nm bandwidth is more than 20 dB when the number of the compressed bits is less than 100. Compression of 25-MHz 10-bit packet to 5 GHz is experimentally demonstrated., IEEE Photonics Technology Letters, 12708 - 710, 01 Jun. 2000
  • An optical packet compressor based on a fiber delay loop
    戸田 裕之
    IEEE Photonics Technology Letters, 12(6)708 - 710, 2000
  • Dense periodic fibers with ultralow four-wave mixing over a broad wavelength range
    A. H. Liang, A. H. Liang, H. Toda, A. Hasegawa
    The four wave mixing (FWM) in dense periodic fibers (DPF) has been determined by generalizing the conventional theory of Hill et al. As compared to conventional dispersion-managed systems and constant-dispersion systems, the FWM in DPF is much less. Designing two sections of DPF with similar effective area reduce the splice loss in DPF, which degrades the signal to noise ratio., Optics Letters, 241094 - 1096, 15 Aug. 1999
  • High-speed soliton transmission in dense periodic fibers
    A. H. Liang, H. Toda, A. Hasegawa
    The transmission of a densely dispersion-managed soliton (DDMS) in dense periodic fiber (DPF) was studied using nonlinear Schrodinger equation. Stable high-speed DDMS can be transmitted in an optimal DPF with low soliton interaction. Even in the presence of higher-order effects, the transmission of the 80-Gbit/s soliton was found to be possible., Optics Letters, 24799 - 801, 15 Jun. 1999
  • Influence of noise in optical pulse source on soliton transmission
    Hiroyuki Toda, Katsuyuki Mino, Katsuyuki Mino, Yuji Kodama, Akira Hasegawa, Peter A. Andrekson
    This paper performed a 10-Gb/s optical soliton transmission experiment in a sliding frequency recirculating loop and found that the noise in optical pulse source decreased error-free distance. This is because the mean frequency of soliton at the pulse source is modulated by the noise which results in the increase of timing jitter at the receiver even in a strong sliding frequency controlled soliton transmission line. Jitter in arrival time of transmitted solitons was theoretically analyzed to verify experimental results., Journal of Lightwave Technology, 171027 - 1031, 01 Jun. 1999
  • 10 Gbit/s optical soliton transmission experiment in a comb-like dispersion profiled fiber loop
    Hiroyuki Toda, Yoshihisa Inada, Yuji Kodama, Akira Hasegawa
    We performed 10 Gbit/s optical soliton transmission experiment over 2,000km with bit error rate of <10-9 in a comb-like dispersion profiled fiber (CDPF) loop of 80 km amplifier spacing which corresponds to 1.8 times of dispersion distance. By reducing the average dispersion of the CDPF, error free distance of 3,000 km was obtained., IEICE Transactions on Communications, E82-B1541 - 1543, 01 Jan. 1999
  • Evaluation of dispersive waves in soliton pulses generated from Mach-Zehnder modulator and singlemode fibre
    H. Toda, N. Yamaguchi, Y. Kodama, T. Shiozaki, A. Hasegawa
    Dispersive wave energy included in a soliton pulse generated from a Mach-Zehnder modulator and a singlemode fibre is evaluated. When pulse repetition is 10GHz, the minimum dispersive wave energy is only 0.23% when the pulsewidth is 23ps, and 3% even when the pulsewidth is 13ps., Electronics Letters, 341246 - 1247, 11 Jun. 1998
  • A feasible all optical soliton based inter-LAN network using time division multiplexing
    Akira Hasegawa, Hiroyuki Toda
    By sacrificing approximately ten percent of the transmission speed, ultra-high speed optical time division multiplexed network can be fully operatable by the use of currently available electrical switches. The network utilizes dispersion managed quasi-solitons and transmits TDM packet which comprises of ATM cells that are introduced from a gateway through bit compression to match to the ultra-high speed traffics. The network can provide flexible bandwidth and bit on demand at burst rate of the maximum LAN speed., IEICE Transactions on Communications, E81-B1681 - 1685, 01 Jan. 1998
  • Improvement of gain and noise figure by periodic bending of an erbium-doped fiber
    A. H. Liang, H. Toda, A. Hasegawa
    The gain and noise figure can be improved by periodic bending of an erbium-doped fiber. Bending of 5.4 m at the beginning of an erbium-doped fiber results in a reduction of noise figure, a gain increment, and a reduction of forward amplified spontaneous emission of 5.1, 3.6, and 1.5 dB for a 1533-nm small signal; 4.0, 1.9, and 2.1 dB for a 1550-nm small signal; and 2.7, 0.9, and 1.8 dB for a 1560-nm small signal (-40 dBm), respectively. In addition, the periodic bending can operate an erbium-doped fiber amplifier at quantum-limited noise and enables its operation to be more stable. © 1997 Optical Society of America., Optics Letters, 221766 - 1768, 01 Dec. 1997
  • Optical soliton transmission experiment in a comb-like dispersion profiled fiber loop
    Hiroyuki Toda, Yasushi Furukawa, Takashi Kinoshita, Yuji Kodama, Akira Hasegawa, Akira Hasegawa
    We discuss the properties of comb-like dispersion profiled fiber (CDPF) for an optical soliton transmission. It is found that the CDPF in which the standard single-mode fiber is placed both at the first and at the end of each section is more suitable to reduce dispersive waves if chirp-free transform limited optical pulse is used as a light source. A 10-ps optical soliton transmission experiment is performed in such a CDPF over 1000 km with the amplifier spacing of 80 km that corresponds to 3.1 times the dispersion distance., IEEE Photonics Technology Letters, 91415 - 1417, 01 Oct. 1997
  • Reduction of dispersive waves by chirping compensation in an optical soliton source with an electro-absorption modulator
    Hiroyuki Toda, Toni Shiozaki, Yasuhiro Maeda, Akira Hasegawa
    A proper amount of group delay dispersion of a dispersion compensating fiber or a single mode fiber reduces chirping of the optical pulse generated by an electroabsorption modulator. Evaluation of the amount of dispersive wave (nonsoliton components) contained in the output of the fiber by means of the inverse scattering transform provides the condition to minimize the dispersive wave generation although it does not generally agree with the condition to minimize the pulse width., Journal of Lightwave Technology, 15743 - 748, May 1997
  • 10-GHz optical soliton transmission experiment in a sliding-frequency recirculating fiber loop
    Hiroyuki Toda, Hiroyuki Yamagishi, Akira Hasegawa
    A 10-GHz optical soliton transmission experiment was performed in a recirculating fiber loop in which the carrier frequency was slowly shifted by an acousto-optic modulator with respect to an optical bandpass filter to simulate the sliding-frequency effect. The soliton pulses were transmitted over 4000 km without any significant change in pulse width. © 1995, Optical Society of America., Optics Letters, 201002 - 1004, 01 Jan. 1995
  • Simple technique to reveal a slow nonlinear mechanism in a z-scanlike n2measurement
    Hiroyuki Toda, Hiroyuki Toda, Carl M. Verber
    We report a simple technique to determine whether the nonlinear mechanism that dominates the results of a z-scan n2measurement is slower than the duration of the exciting pulse. In this technique, the temporal waveform of the beam transmitted through an aperture is observed, instead of total energy per pulse as in a normal z-scan measurement. Using a doubled Nd:YAG laser, we observed a slow response in index change in the absorptive material methyl nitroaniline, whereas CS2showed fast response compared with the laser pulse width of 65 ns. © 1992 Optical Society of America., Optics Letters, 171379 - 1381, 01 Oct. 1992
  • Integrated-Optic Heterodyne Interferometer for Displacement Measurement
    Hiroyuki Toda, Masamitsu Haruna, Hiroshi Nishihara
    An integrated-optic heterodyne interferometer is proposed and demonstrated for displacement measurement with an accuracy of several nanometers. All guided-wave components required for displacement measurement, including a serrodyne phase modulator, TE-TM mode converters, and a mode splitter, are integrated on a Z-propagating LiNb03 substrate of 47 × 5 mm2. Using the fabricated optical IC, phase difference between reference and signal beats has been steadily detected without stabilization against substrate temperature change. The phase difference between two beats was successfully measured, showing an accuracy of ± 3 nm in the displacement measurement. © 1991 IEEE, Journal of Lightwave Technology, 9683 - 687, 01 Jan. 1991
  • An Optical Integrated Circuit for Time-Division 2-D Velocity Measurement
    Hiroyuki Toda, Kenichi Kasazumi, Masamitsu Haruna, Hiroshi Nishihara
    We propose and demonstrate a novel LiNbO3 optical integrated circuit (optical IC) pigtailed with two single-mode fibers, which allows time-division two-dimensional (2-D) velocity measurement. To detect time-division multiplexed beat signals corresponding to velocity components vxand v yof a moving object, a waveguide switch is integrated on a Z-propagating LiNbO3 substrate of 28 × 7 mm2 in addition to a waveguide interferometer with a frequency shifter. In the tested optical IC, either vxor vy could be measured selectively with the signal-to-noise ratio of 20 dB by driving an electronic gate placed after a photodiode in synchronization with the waveguide switch. © 1989 IEEE, Journal of Lightwave Technology, 7364 - 367, 01 Jan. 1989
  • Optical integration of a fiber laser doppler velocimeter
    Hiroyuki Toda, Masamitsu Haruna, Hiroshi Nishihara
    This paper describes an optical integrated circuit (optical IC) for a laser Doppler velocimeter (LDV) in which a polarization‐maintaining optical fiber is used to pick up a signal light. To realize more compact and stable heterodyne optics for velocity measurement, a waveguide interferometer including a frequency shifter, a TE/TM mode converter, and a TE/TM mode splitter is integrated on a Z‐propagating LiNbO3 substrate 32 × 7 mm2 in size. In the fabrication of the optical IC, a 3‐μm wide waveguide pattern was made by a laser‐beam direct writing method. The polarizationmaintaining optical fiber was butt‐coupled to the output waveguide of the optical IC. Using the fabricated optical IC, the Dopplershifted signal light was detected with the signal‐to‐noise ratio of 25 dB in the velocity measurement of a moving mirror. The configuration of the optical IC, properties of key waveguide components, fabrication and velocity measurement characteristics of the optical IC, are described in this paper. Copyright © 1988 Wiley Periodicals, Inc., A Wiley Company, Electronics and Communications in Japan (Part II: Electronics), 7196 - 108, 01 Jan. 1988
  • Laser-beam writing system for optical integrated circuits
    Masamitsu Haruna, S. Yoshida, H. Toda, H. Nishihara
    A computer-controlled laser-beam writing system has been developed for optical integrated circuits (optical ICs). This system allows us to make waveguidepatterns 'formula presented' wide, such as directional couplers, and Yjunction, crossed, and S-shaped waveguides, automatically within an edge roughness of 'formula presented' on a photoresist- coated 'formula presented' substrate. By combining these waveguide patterns, optical ICs can be delineated over more than 50-mm length. This paper presents the system description and the laser-beam writing characteristics of key waveguide patterns. The integrated-optic fiber laser Doppler velocimeter is also demonstrated as an example of large-area optical ICs. © 1987, Optical Society of America., Applied Optics, 264587 - 4592, 01 Jan. 1987
  • Optical Integrated Circuit For a Fiber Laser Doppler Velocimeter
    Hiroyuki Toda, Masamitsu Haruna, Hiroshi Nishihara
    In this paper, we propose and demonstrate a new optical integrated circuit (optical IC) pigtailed with a polarization-maintain-ing fiber for the laser Doppler velocimeter. In this optical IC, a waveguide frequency shifter, a TE/TM mode converter, and a mode splitter are integrated in Z-propagation Ti-diffused LiNbO<inf>3</inf> as well as a waveguide interferometer. Since the optical IC is as long as 32 mm, the waveguide patterning has been made with < 0.2-μm accuracy by a laser-beam lithographic system recently developed. Using the fabricated optical IC, the velocity of a moving object has been successfully heterodyne-detected with the signal-to-noise ratio of 25 dB. Copyright © 1987 by The Institute of Electrical and Electronics, Inc., Journal of Lightwave Technology, 5901 - 905, 01 Jan. 1987
  • Integrated-optic device for a fibre laser doppler velocimeter
    H. Toda, M. Haruna, H. Nishihara
    We first demonstrate an integrated-optic device for a fibre laser Doppler velocimeter, which consists of a waveguide interferometer and a frequency shifter in z-propagation Ti-diffused LiNbO3. The device is also pigtailed with a single-mode fibre to pick up a Doppler-shifted signal. Using the fabricated device, the velocity of a moving object was successfully heterodyne-detected with a signal/noise ratio of 30 dB. © 1986, The Institution of Electrical Engineers. All rights reserved., Electronics Letters, 22982 - 984, 01 Jan. 1986

Misc

  • 28Gbps PAM4 60GHz radio over fiber system by injection locking two-tone light to directly-modulated laser
    Guo Wei Lu, Guo Wei Lu, Ruben S. Luis, Hiroyuki Toda, Jiabin Cui, Takahide Sakamoto, Hongxiang Wang, Yuefeng Ji, Naokatsu Yamamoto
    © 2018 OSA. A 28Gbps PAM4 60GHz radio-over-fiber system is proposed and experimentally demonstrated by injection locking a two-tone light to a directly-modulated laser. Experimental results show negligible power penalty for the obtained PAM4 after the injection locking., 2018 Conference on Lasers and Electro-Optics, CLEO 2018 - Proceedings, 06 Aug. 2018
  • Millimeter-wave communication system using photonic-based remote antennas for configurable network in dense user environment
    Hiroshi Murata, Yui Otagaki, Naruto Yonemoto, Yasuyuki Kakubari, Kensuke Ikeda, Nobuhiko Shibagaki, Hiroyuki Toda, Hiroshi Mano, Usman Habib, Nathan Gomes
    © 2017 IEEE. Photonic-based millimeter-wave communication systems combined with conventional wireless systems have been proposed for the application in dense user environments like a large football stadium. By utilizing a narrow beam antenna for millimeter-wave asymmetric links, effective communication channels can be obtained., 2017 IEEE Conference on Antenna Measurements and Applications, CAMA 2017, 2018-January24 - 27, 29 Jan. 2018
  • Output power enhancement in photonic-based 60-GHz generation by optical pulse compression with a dispersion shifted fiber
    Takashi Yamaguchi, Shigenobu Sakakibara, Yui Otagaki, Hiroshi Murata, Hiroyuki Toda
    © 2017 IEEE. In this manuscript, we propose to use optical pulse compression in a dispersion-shifted fiber (DSF) to enhance the output power in photonic-based RF generation. In a 60-GHz RF generation experiment using a DSF, an RF gain due to the optical pulse compression of 5.2 dB was obtained at a DSF length of 15 km and an average optical power to the DSF of 20.0 dBm., MWP 2017 - 2017 International Topical Meeting on Microwave Photonics, 2017-December1 - 3, 05 Dec. 2017
  • Output power enhancement in photonic-based RF generation by optical pulse compression with a constant dispersion fiber
    Takashi Yamaguchi, Hiroyuki Toda
    © 2017 OSA. Microwave and millimeter-wave generation based on photonic technology [1-3] is promising for many applications. In this method, the RF output power is limited by the maximum average optical power to the photo detector (PD). Therefore, photodiodes with high optical power handling are necessary if high RF output power is required. Hirata et al. reported that if the optical pulse width to the PD is narrower, though the average power to the PD is the same, the RF output power is enhanced since the fundamental frequency component included in the PD input is increased [4]. Kuo et al. theoretically analyzed this phenomenon with a phase-locked optical frequency comb with equal amplitude [5] and derived that the RF power is enhanced by 6 dB when the number of comb lines is increased from two (optical two-tone) to infinite (zero pulse width). So far, 100-GHz [5] and 160-GHz [6] RF generations have been reported by using short optical pulses to the PD. The use of an optical frequency comb and a spectral pulse shaper enables us to shorten the optical pulse width. Recently, we have proposed a new simple approach that utilizes an optical pulse compression in a constant dispersion optical fiber, which is performed by the combined effects of group velocity dispersion and self phase modulation [7, 8]. The optical pulse width can be shortened by properly adjusting the fiber length and launched power to the fiber in accordance with the fiber dispersion and pulse repetition frequency. In this talk, we present operational principle of the proposed method, results of simulation and experiment of 20-GHz RF generation using a standard single-mode fiber, and the simulation results for investigating the possibility of 100-GHz and 300-GHz RF generation., Optics InfoBase Conference Papers, Part F83-ACPC 2017, 01 Jan. 2017
  • Millimeter-Wave Communication System Using Photonic-Based Remote Antennas for Configurable Network in Dense User Environment
    2017 IEEE CONFERENCE ON ANTENNA MEASUREMENTS & APPLICATIONS (CAMA), 24 - 27, 2017
  • Millimeter-wave wireless signal generation and detection using photonic technique for mobile communication systems
    Toshiyuki Inoue, Kensuke Ikeda, Yasuyuki Kakubari, Naruto Yonemoto, Nobuhiko Shibagaki, Hiroyuki Toda, Hiroshi Murata
    © 2016 IEEE. We have been trying to develop photonic devices and sub-systems for radio-over-fiber based wireless mobile communication in dense-user environments. We report demonstrations of millimeter-wave wireless signal generation using optical 2-Tone and its detection by use of array-Antenna-electrode electrooptic modulators., 2016 IEEE International Topical Meeting on Microwave Photonics, MWP 2016, 55 - 58, 19 Dec. 2016
  • Output power enhancement by optical pulse compression in photonic-based RF generation
    Takashi Yamaguchi, Hiroki Morimoto, Hiroyuki Toda
    © 2016 IEEE. Microwave and millimeter-wave generation based on photonic technology is promising for many applications. However, the RF output power is limited by the maximum optical power to the photo detector. In this manuscript we propose to use optical pulse compression in order to enhance the output power. We make a numerical simulation of the transmitted optical pulse in an optical fiber, and the generated RF output power after the photo detection is calculated. The calculated results show that the output power is effectively enhanced with the combination of anomalous dispersion and optical Kerr nonlinearity. Furthermore, we experimentally confirm that the RF power is enhanced by the use of shorter optical pulse., 2016 URSI Asia-Pacific Radio Science Conference, URSI AP-RASC 2016, 1528 - 1530, 19 Oct. 2016
  • Suppression of optical spectrum fluctuations by stabilizing fiber loop length in optical comb generator using an optical SSB modulator
    Yoshiki Onishi, Norimasa Nagatani, Hiroyuki Toda, Tetsuya Kawanishi
    © 2015 IEEE. In this paper, we investigate the optical power fluctuation of the output in optical comb generator using an optical single sideband (SSB) modulator with a fiber loop. This fluctuation is caused by undesired sidebands of the SSB modulator. We show that the fluctuation can be suppressed by stabilizing the fiber loop length. In experiment, the averaged peak-to-peak power fluctuation of 23 comb outputs was suppressed from 0.86 dB to 0.13 dB., 2015 International Topical Meeting on Microwave Photonics, MWP 2015 - Conference Proceedings, 14 Dec. 2015
  • Narrowing of IF band pass filter bandwidth in spurious suppressed opto-electronic microwave oscillator
    Takashi Yamaguchi, Hiroki Morimoto, Hiroyuki Toda
    We examine the influence of the narrow IF BPF on phase noise of spurious suppressed opto-electronic microwave oscillators. We found that the phase noise cancellation is effective only within the bandwidth of the IF BPF. © 2015 OSA., Asia Communications and Photonics Conference, ACPC 2015, 11 Dec. 2015
  • Optimization of an optical bandpass filter on a stabilized quadruple OTDM multiplier for RZ/CS-RZ optical clock
    Pierre Buechler, Kiyotaka Sugiyama, Hiroyuki Toda
    © 2014 IEICE. We are focusing on the study of a phase stabilized quadruple RZ/CS-RZ optical clock multiplier. A flat-top optical bandpass filter (OBPF) is used to filter 3 consecutive optical sidebands from the OTDM multiplexed output. The filtered output is used for the phase stabilization. In this presentation, we made a simulation to obtain the tolerance of center frequency of the filter versus its bandwidth and shape factor in order to find out the required OBPF parameters for the optical clock multiplier., 2014 International Topical Meeting on Microwave Photonics / the 9th Asia-Pacific Microwave Photonics Conference, MWP/APMP 2014 - Proceedings, 280 - 283, 01 Jan. 2014
  • Influence of harmonic distortions of driving signal on the measurement of Mach-Zehnder modulator parameters
    Yuji Nishi, Naoya Ichino, Takahiro Hayashi, Hiroyuki Toda, Tetsuya Kawanishi
    © 2014 IEICE. In this paper, we describe the influence of harmonic distortions of RF driving signal on the measurement of Mach-Zehnder modulator parameters, those are half-wave voltage and intrinsic chirp parameter. The influences on the measured parameters were experimentally verified in the presence of 2nd and 3rd order harmonic distortions individually., 2014 International Topical Meeting on Microwave Photonics / the 9th Asia-Pacific Microwave Photonics Conference, MWP/APMP 2014 - Proceedings, 117 - 120, 01 Jan. 2014
  • A phase stabilized quadruple OTDM multiplier for RZ/CS-RZ optical clock with a flat-top optical bandpass filter
    Buechler Pierre, OTSUKI Masato, Toda Hiroyuki
    Our work focuses on the study of a phase stabilized quadruple RZ/CS-RZ optical clock multiplier. This quadruple OTDM multiplier is composed of two Mach-Zehnder interferometers. In this presentation, we propose to use a flat top OBPF to filter three desired sidebands from the OTDM multiplexed output. The filtered output is used for the stabilization. Further simulations were done to characterize the influence of OBPF shape on stabilization., Technical report of IEICE. OPE, The Institute of Electronics, Information and Communication Engineers, Technical report of IEICE. OPE, 113(144)143 - 146, 18 Jul. 2013, English
  • Influence of harmonic distortions of driving signal on chirp parameter measurement of mach-zehnder modulator - Experimental verification
    Takahiro Hayashi, Hiroyuki Toda, Tetsuya Kawanishi
    In this paper, we describe the influence of harmonic distortions of RF driving signal on chirp parameter measurement of a Mach-Zehnder modulator. The influence was experimentally verified for the first time. © OSA 2013., Asia Communications and Photonics Conference, ACP, 01 Jan. 2013
  • Stabilization of 40Gbit/s optical DQPSK demodulator
    NISHIOKA Masaki, CHIKAMOTO Takuya, SHIMIZU Tatsuya, TODA Hiroyuki, INAFUNE Koji, KAGAWA Masatoshi, MURAI Hitoshi
    電気学会研究会資料. EMT, 電磁界理論研究会, 電気学会研究会資料. EMT, 電磁界理論研究会, 2012(76)101 - 104, 26 Jul. 2012, Japanese
  • A phase stabilized quadruple OTDM Multiplier for RZ/CZ-RZ optical clock with and optical bandpass filter
    OTSUKI Masato, TAKAMA Renjo, TODA Hiroyuki
    We demonstrate a phase stabilized quadruple OTDM multiplier for RZ/CS-RZ optical clock. An optical bandpass filter (OBPF) was used to filter the desired sideband from the multiplier output, and the filtered output was used for the stabilization. In calculation, we found that the existence of OBPF crosstalk was effective for the stabilizing operation. In experiment, 10GHz optical clock was multiplied to 40GHz with 17dB undesired sideband suppression ratio., Technical report of IEICE. OPE, The Institute of Electronics, Information and Communication Engineers, Technical report of IEICE. OPE, 112(156)185 - 189, 19 Jul. 2012, Japanese
  • Satbilization of 40 Gbit/s optical DQPSK demodulator
    NISHIOKA Masaki, CHIKAMOTO Takuya, SHIMIZU Tatsuya, TODA Hiroyuki, INAFUNE Koji, KAGAWA Masatoshi, MURAI Hitoshi
    We demonstrate a stabilization of 40Gbit/s optical DQPSK demodulator using a wavelength tunable CW laser. The BER of the received data was stabilized., Technical report of IEICE. OPE, The Institute of Electronics, Information and Communication Engineers, Technical report of IEICE. OPE, 112(156)101 - 104, 19 Jul. 2012, Japanese
  • A phase stabilized quadruple OTDM Multiplier for RZ/CZ-RZ optical clock with and optical bandpass filter
    OTSUKI Masato, TAKAMA Renjo, TODA Hiroyuki
    We demonstrate a phase stabilized quadruple OTDM multiplier for RZ/CS-RZ optical clock. An optical bandpass filter (OBPF) was used to filter the desired sideband from the multiplier output, and the filtered output was used for the stabilization. In calculation, we found that the existence of OBPF crosstalk was effective for the stabilizing operation. In experiment, 10GHz optical clock was multiplied to 40GHz with 17dB undesired sideband suppression ratio., 電子情報通信学会技術研究報告. MWP, マイクロ波・ミリ波フォトニクス = IEICE technical report. MWP, Microwave and millimeter-wave photonics, The Institute of Electronics, Information and Communication Engineers, 電子情報通信学会技術研究報告. MWP, マイクロ波・ミリ波フォトニクス = IEICE technical report. MWP, Microwave and millimeter-wave photonics, 112(158)185 - 189, 19 Jul. 2012, Japanese
  • Satbilization of 40 Gbit/s optical DQPSK demodulator
    NISHIOKA Masaki, CHIKAMOTO Takuya, SHIMIZU Tatsuya, TODA Hiroyuki, INAFUNE Koji, KAGAWA Masatoshi, MURAI Hitoshi
    We demonstrate a stabilization of 40Gbit/s optical DQPSK demodulator using a wavelength tunable CW laser. The BER of the received data was stabilized., 電子情報通信学会技術研究報告. MWP, マイクロ波・ミリ波フォトニクス = IEICE technical report. MWP, Microwave and millimeter-wave photonics, The Institute of Electronics, Information and Communication Engineers, 電子情報通信学会技術研究報告. MWP, マイクロ波・ミリ波フォトニクス = IEICE technical report. MWP, Microwave and millimeter-wave photonics, 112(158)101 - 104, 19 Jul. 2012, Japanese
  • B-10-35 A quadruple OTDM multiplier for RZ/CS-RZ optical clock by means of stabilized delayed interferometers with an optical bandpass filter
    Otsuki Masato, Takama Renjo, Toda Hiroyuki
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2012(2), 06 Mar. 2012, Japanese
  • A phase stabilized quadruple OTDM multiplier for RZ/CS-RZ optical clock with an optical bandpass filter
    Masato Otsuki, Renjo Takama, Hiroyuki Toda
    We demonstrate a phase stabilized quadruple OTDM multiplier for RZ/CS-RZ optical clock. An optical bandpass filter (OBPF) was used to filter the desired sideband from the multiplier output, and the filtered output was used for the stabilization. 10 GHz optical clock was multiplied to 40 GHz with 17 dB undesired sideband suppression ratio. © OSA 2012., Asia Communications and Photonics Conference, ACP, 01 Jan. 2012
  • Stabilization of 40 Gbit/s optical DQPSK receiver
    Takuya Chikamoto, Masaki Nishioka, Tatsuya Shimizu, Hiroyuki Toda, Koji Inafune, Masatoshi Kagawa, Hitoshi Murai
    We demonstrate a stabilization of 40 Gbit/s optical DQPSK receiver using a wavelength tunable CW laser. The BER of the received data was successfully stabilized. © OSA 2012., Asia Communications and Photonics Conference, ACP, 01 Jan. 2012
  • Frequency response measurement of half-wave voltage and chirp parameter of LiNbO 3 intensity modulators in low frequency range
    Kimihiro Toki, Dai Uesaka, Takahiro Yamazaki, Hiroyuki Iwata, Masahisa Yoshikawa, Hiroyuki Toda, Tetsuya Kawanishi
    We measured frequency responses of half-wave voltage V π and chirp parameter α 0 of LiNbO 3 modulators below 1 GHz range using optical heterodyne scheme with an acousto-optic modulator. The coefficients of variation of the measured values of V π and α 0 are 0.2 % and 2 %, respectively. We observed strong dependency of V π and α 0 on the frequency. © 2011 IEEE., 2011 IEEE International Topical Meeting on Microwave Photonics - Jointly Held with the 2011 Asia-Pacific Microwave Photonics Conference, MWP/APMP 2011, 354 - 356, 26 Dec. 2011
  • Stabilization of a delay interferometer for variable bit-rate DPSK receiver from 40 Gbit/s up to 160 Gbit/s
    Tatsuya Shimizu, Masafumi Nagao, Takuya Chikamoto, Koji Inafune, Masatoshi Kagawa, Hitoshi Murai, Hiroyuki Toda
    We demonstrate stabilization of a delay interferometers (DI) for variable bit-rate DPSK receiver from 40 Gbit/s up to 160 Gbit/s using a wavelength tunable CW laser. The phase difference is continuously tunable by tuning the CW laser. The BER of the received 41.25 Gbit/s DPSK signal was successfully stabilized. No noticeable degradation was observed in the eye patterns when the bit rate is 82.5 Gbit/s and 165 Gbit/s. Keywords-component; optical DPSK receiver, delay interferometer, stabilization © 2011 IEEE., IEEE Photonic Society 24th Annual Meeting, PHO 2011, 773 - 774, 01 Dec. 2011
  • Reconfigurable DWDM millimeter-wave band radio-over-fiber technologies
    Hiroyuki Toda, Juan Jose Vegas Olmos, Juan Jose Vegas Olmos, Toshiaki Kuri, Ken Ichi Kitayama
    We describe reconfigurable DWDM millimeter-wave band radio-over-fiber (RoF) access system technologies. Focuses are on optical frequency interleaving, supercontinuum multi-wavelength light source and photonic up/down conversion for RoF signals, and optical path switching for dynamic channel allocation for wireless services. © 2011 IEEE., IEEE Photonic Society 24th Annual Meeting, PHO 2011, 266 - 267, 01 Dec. 2011
  • B-10-77 Stabilization of 41.25 Gbit/s DPSK demodulator with an optical bandpass filter
    Chikamoto Takuya, Shimizu Tatsuya, Nagao Masafumi, Toda Hiroyuki, Inafune Koji, Kagawa Masatoshi, Murai Hitoshi
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 2011(2), 30 Aug. 2011, Japanese
  • Frequency Response Measurement of Half-Wave Voltage and Chirp Parameter of LiNbO_3 Intensity Modulators in Low Frequency Range
    TOKI Kimihiro, UESAKA Dai, YAMAZAKI Takahiro, IWATA Hiroyuki, YOSHIKAWA Masahisa, TODA Hiroyuki, KAWANISHI Tetsuya
    We measured frequency response of half-wave voltage V_π and chirp parameter α_0 of LiNbO_3 modulators below 1 GHz range using optical heterodyne scheme with an acousto-optic modulator. We observed strong dependency of V_π and α_0 on the frequency., IEICE technical report, The Institute of Electronics, Information and Communication Engineers, IEICE technical report, 111(150)105 - 108, 14 Jul. 2011, English
  • 160 Gbit/s RZ/CS-RZ OTDM multiplexer with stabilization of phase difference between adjacent optical pulses
    SHIMIZU Tatsuya, NAGAO Masafumi, INAFUNE Koji, KAGAWA Masatoshi, MURAI Hitoshi, TODA Hiroyuki
    We demonstrated a 160 Gbit/s RZ/CS-RZ OTDM multiplexer, where optical phase between adjacent channels was stabilized. Optical bandpass filters were used to pick up carrier component of the multiplexer output for the stabilization. The optical spectrum of the output was stabilized with 0.2 dB variation with temperature change between 26℃ and 32℃., IEICE technical report, The Institute of Electronics, Information and Communication Engineers, IEICE technical report, 111(92)33 - 37, 16 Jun. 2011, Japanese
  • B-10-83 Stabilization of a variable bit-rate delay interferometer-40 Gbit/s DPSK demodulation characteristics
    Nagao Masafumi, Shimizu Tatsuya, Chikamoto Takuya, Toda Hiroyuki, Inafune Koji, Kagawa Masatoshi, Murai Hitoshi
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2011(2), 28 Feb. 2011, Japanese
  • Active bit-wise phase stabilization in 160 Gbit/s RZ/CS-RZ OTDM multiplexer
    M. Nagao, T. Shimizu, M. Tanimura, Y. Murata, K. Inafune, M. Kagawa, H. Murai, H. Toda
    We demonstrate a 160 Gbit/s RZ/CS-RZ OTDM multiplexer, where optical phase between adjacent channels was stabilized. The use of optical bandpass filter to pick up carrier or sideband component of the multiplexer output eliminates the needs for a tunable CW laser. The optical spectrum of the output was stabilized with temperature change between 26°C and 32°C. ©2010 IEEE., 2010 Asia Communications and Photonics Conference and Exhibition, ACP 2010, 431 - 432, 01 Dec. 2010
  • Multi-interchannel crosstalk in a DWDM millimeter-wave-band radio-over-fiber
    Kenji Nitta, Hiroyuki Toda, Toshiaki Kuri, Ken Ichi Kitayama
    In this paper, we numerically investigate the influence of multi-interchannel optical crosstalk in a 25-GHz spaced dense-wavelength division multiplexing (DWDM) millimeter-wave-band radio-over-fiber (RoF) downlink system. Up to 31 undesired RoF signals were intentionally mixed as the crosstalk with the desired RoF signal. We define the suppression ratio of the crosstalk as the ratio of the mm-wave power of the desired channel to the undesired channels which are estimated from optical spectrum of the detected RoF signal. The simulation results show that the receiver sensitivity degradation due to the crosstalk can be fairly well predicted with the measurable suppression ratio regardless of the total DWDM channel number. ©2010 IEEE., Proceedings - 2010 IEEE International Topical Meeting on Microwave Photonics, MWP 2010, 339 - 342, 01 Dec. 2010
  • Active bit-wise phase stabilization in 80 Gbit/s RZ/CS-RZ OTDM multiplexer
    T. Shimizu, Y. Murata, M. Tanimura, M. Nagao, K. Inafune, M. Kagawa, H. Murai, H. Toda
    We demonstrated an 80 Gbit/s RZ/CS-RZ OTDM multiplexer, where optical phase between adjacent channels was stabilized. The use of optical bandpass filter to pick up carrier or sideband component of the multiplexer output eliminates the needs for a tunable CW laser. The optical spectrum of the output was stabilized with temperature change between 26°C and 34°C., Technical Digest - 15th OptoElectronics and Communications Conference, OECC2010, 770 - 771, 29 Nov. 2010
  • B-10-28 Active bit-wise phase stabilization in 160 Gbit/s RZ/CS-RZ OTDM multiplexer
    Nagao Masafumi, Shimizu Tatsuya, Tanimura Masayoshi, Inafune Koji, Kagawa Masatoshi, Murai Hitoshi, Toda Hiroyuki
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 2010(2), 31 Aug. 2010, Japanese
  • 80Gbit/s RZ/CS-RZ OTDM multiplexer with stabilization of phase difference between adjacent optical pulses
    SHIMIZU Tatsuya, TANIMURA Masayoshi, NAGAO Masafumi, INAFUNE Koji, KAGAWA Masatoshi, MURAI Hitoshi, TODA Hiroyuki
    We demonstrated an 80 Gbit/s RZ/CS-RZ OTDM multiplexer, where optical phase between adjacent channels was stabilized. The use of optical bandpass filter to pick up carrier or sideband component of the multiplexer output, which is used for the stabilization, eliminates the needs for a tunable CW laser. The optical spectrum of the output was stabilized with temperature change between 26℃ and 34℃., IEICE technical report, The Institute of Electronics, Information and Communication Engineers, IEICE technical report, 110(156)57 - 62, 22 Jul. 2010, Japanese
  • C-14-9 Influence of multi-channel crosstalk in 25-GHz spaced DWDM millimeter-wave-band radio-over-fiber system : Simulation
    Yamaguchi Takashi, Nitta Kenji, Toda Hiroyuki, Kuri Toshiaki, Kitayama Ken-ichi
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2010(1), 02 Mar. 2010, Japanese
  • C-3-71 Frequency response measurement of half-wave voltage and chirp parameter of LiNbO_3 intensity modulators in low frequency range
    Iwata Hiroyuki, Yoshikawa Masahisa, Toda Hiroyuki, Kawanishi Tetsuya
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2010(1), 02 Mar. 2010, Japanese
  • B-10-95 Active bit-wise phase stabilization in 80 Gbit/s RZ/CS-RZ OTDM multiplexer
    Murata Yuki, Shimizu Tatsuya, Tanimura Masayoshi, Nagao Masafumi, Inafune Koji, Kagawa Masatoshi, Murai Hitoshi, Toda Hiroyuki
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2010(2), 02 Mar. 2010, Japanese
  • B-10-74 Stabilization of phase difference between adjacent optical pulses in 80 Gbit/s OTDM multiplexer
    Miyashita Junichi, Murata Yuki, Nagao Masafumi, Toda Hiroyuki
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2010, Japanese
  • Fiber-wireless DWDM networks and radio-over-fiber technologies
    Toshiaki Kuri, Hiroyuki Toda, Juan Jose Vegas Olmos, Juan Jose Vegas Olmos, Ken Ichi Kitayama
    Dense wavelength division multiplexing network of coexisting analog radio-over-fiber and digital fiber-to-the-home signals is presented, by focusing on enabling techniques including optical frequency interleaving, supercontinuum light source, and photonic dynamic channel allocation for wireless services., MWP09 - 2009 International Topical Meeting on Microwave Photonics, 29 Dec. 2009
  • A 160 Gbit/s (4 × 40 Gbit/s) OTDM multiplexer with active bit-wise phase stabilization
    Y. Murata, M. Nagao, J. Miyashita, K. Inafune, M. Kagawa, H. Murai, H. Toda
    We demonstrated a 160 Gbit/s OTDM multiplexer, where optical phase between adjacent channels was stabilized with a CW laser. The optical spectrum variation was within 0.4 dB with temperature change between 15°C and 35°C. © 2009 IEEE., Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS, 489 - 490, 29 Dec. 2009
  • Wired and wireless integrated DWDM networks and millimeter-wave-band RoF technologies
    Toshiaki Kuri, Juan Jose Vegas Olmos, Juan Jose Vegas Olmos, Hiroyuki Toda, Ken Ichi Kitayama
    Dense wavelength division multiplexing network of co-existing analog radio-over-fiber and digital fiber-to-the-home signals is presented, by focusing on enabling techniques including optical frequency interleaving, supercontinuum multi-wavelength light source, and photonic dynamic channel allocation. © 2009 IEEE., Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS, 677 - 678, 29 Dec. 2009
  • Pure intensity modulated frequency doubled optical clock signal generation by using ultra low-chirp and high extinction-ratio optical modulation
    Tetsuya Kawanishi, Takahide Sakamoto, Akito Chiba, Hiroyuki Toda, Hiroshi Murata, Akira Enokihara
    We demonstrated ultra low-chirp and high extinction-ratio modulation, by using an integrated lithium niobate modulator. The odd order optical sideband components were highly suppressed to achieve a chirp-free intensity modulated frequency doubled signal. © 2009 IEEE., 2009 14th OptoElectronics and Communications Conference, OECC 2009, 10 Nov. 2009
  • 160Gbit/s OTDM multiplexer with stabilization of phase differencce between adjacent optical pulses
    NAGAO Masafumi, MURATA Yuki, MIYASHITA Junichi, INAFUNE Koji, KAGAWA Masatoshi, MURAI Hitoshi, TODA Hiroyuki
    Phase difference between adjacent optical pulses is stabilized by means of stabilization of a delay interferometer (DI), which can be considered as an optical time-division multiplexed (OTDM) multiplexer. A continuous wave (CW) tunable laser, where the wavelength is different from that of the optical pulse, was used to stabilize the DI. We applied this stabilization scheme to a 160Gbit/s (4×40Gbit/s) OTDM multiplexer. In the experiment, we have confirmed that the variation of the optical spectrum for CS-RZ output was suppressed within 0.6dB with temperature change between 15℃ and 35℃., IEICE technical report, The Institute of Electronics, Information and Communication Engineers, IEICE technical report, 109(243)87 - 91, 15 Oct. 2009, Japanese
  • B-10-38 Stabilization of phase difference between adjacent optical pulses in 160 Gbit/s OTDM multiplexer
    Nagao Masafumi, Murata Yuki, Miyashita Junichi, Inafune Koji, Kagawa Masatoshi, Murai Hitoshi, Toda Hiroyuki
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 2009(2), 01 Sep. 2009, Japanese
  • 80Gbit/s OTDM multiplexer with stabilization of phase difference between adjacent optical pulses
    MURATA Yuki, NAGAO Masafumi, MIYASHITA Junichi, INAFUNE Koji, KAGAWA Masatoshi, MURAI Hitoshi, TODA Hiroyuki
    Phase difference between adjacent optical pulses is stabilized by means of stabilization of a delay interferometer (DI), which can be considered as an optical time-division multiplexed (OTDM) multiplexer. A continuous wave (CW) tunable laser, where the wavelength is different from that of the optical pulse, was used to stabilize the DI. We applied this stabilization scheme to an 80Gbit/s (2x40Gbit/s) OTDM multiplexer. In the experiment, we have confirmed that the variation of the optical spectrum for both RZ and CS-RZ output was suppressed with temperature change between 15℃ and 35℃, IEICE technical report, The Institute of Electronics, Information and Communication Engineers, IEICE technical report, 109(159)185 - 189, 23 Jul. 2009, Japanese
  • Phase Difference Control between Adjacent Optical Pulses by Means of Stabilization of Delayed Interferometer and Its Application to an OTDM Multiplier for RZ Optical Clock
    Toda Hiroyuki, Miyashita Junichi
    遅延干渉計の光路差を制御・安定化することによって、隣接光パルス間の位相を安定化した光時分割多重回路について検討した。安定化には、入力光パルスと波長の異なる連続光の干渉を利用した。ピエゾ素子とロックインアンプを用いてフィードバックをかけ、連続光の波長を変えることによって、8π以上にわたって位相差を制御できることを確認した。さらに、ファイバ型遅延干渉計を2台接続した光クロックの4逓倍回路を作成し、1台の波長可変レーザによる制御で、40GHzの同相および位相反転光クロックを生成した。Phase difference between adjacent optical pulses is stabilized by means of stabilization of a delayed interferometer (DI), which can be considered as an optical time-division multiplexed (OTDM) multiplexer. A continuous wave (CW) tunable laser, where the wavelength is different from that of the optical pulse, was used to stabilize the DI. We have confirmed that the phase difference of more than 8 p was controlled using a piezo-electric transducer and a lock-in amplifier by tuning the CW laser wavelength. Moreover, we investigated an optical clock quadruple multiplier by serially concatenating the OTDM multiplexer. In 40GHz optical clock generation experiment, we have observed the temporal waveforms and optical spectra when in-phase and out-of phase optical clocks were successfully generated, respectively. The undesired optical sidebands were suppressed to be more than 15 dB for both cases., The science and engineering review of Doshisha University, 同志社大学, 同志社大学理工学研究報告, 50(1)54 - 58, Apr. 2009, Japanese
  • Multi-channel crosstalk in a 25-GHz spaced DWDM millimeter-wave-band radio-over-fiber system
    Takashi Yamaguchi, Yoshitomo Takahashi, Hiroyuki Toda, Toshiaki Kuri, Toshiaki Kuri, Ken Ichi Kitayama
    In this paper, we experimentally investigate the influence of multi-channel optical crosstalk in a 25-GHz spaced dense-wavelength division multiplexing (DWDM) millimeter-wave-band radio-over-fiber (RoF) downlink system. The eleven-channel crosstalk filtered with arrayed waveguide gratings (AWGs) was intentionally mixed with the desired channel of the RoF signal. We defined the suppression ratio of the crosstalk as the ratio of the mm-wave power of the desired channel and undesired channels which are estimated from optical spectrum of the detected RoF signal. The experimental results show that the power penalty due to the crosstalk of less than 1 dB is obtained when the suppression ratio is more than 25 dB. ©2008 IEEE., 2008 IEEE International Meeting on Microwave Photonics jointly held with the 2008 Asia-Pacific Microwave Photonics Conference, MWP2008/APMP2008, 185 - 188, 01 Dec. 2008
  • Highly pure 160-GHz two-tone lightwave generation using high extinction-ratio optical intensity modulator and delay interferometer
    Hiroyuki Toda, Junichi Miyashita, Akito Chiba, Takahide Sakamoto, Tetsuya Kawanishi, Masahiro Tsuchiya, Masayuki Izutsu
    We demonstrate highly pure 160-GHz two-tone lightwave generation using a high extinction-ratio optical intensity modulator and a delay interferometer. The undesired sideband suppression ratio was more than 39 dB. ©2008 IEEE., Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS, 421 - 422, 01 Dec. 2008
  • Fully-interleaved WDM reconfigurable baseband (2.5-Gbit/s) and 60-GHz (155-Mbit/s) millimeter-wave-band Radio-over-Fiber access network
    J. J.Vegas Olmos, Toshiaki Kuri, Takahiro Sono, Kazunori Tamura, Hiroyuki Toda, Ken Ichi Kitayama
    We propose and demonstrate a fully-interleaved WDM dynamic reconfigurable 155-Mbit/s 60GHz millimeter-wave-band radio-over-fiber (RoF) and 2.5-Gbit/s baseband access network. © 2008 IEEE., European Conference on Optical Communication, ECOC, 01 Dec. 2008
  • Measurement of Mach-Zehnder interferometer based modulators by using optical spectrum analysis
    KAWANISHI Tetsuya, SAKAMOTO Takahide, CHIBA Akito, TODA Hiroyuki, ENOKIHARA Akira, MURATA Hiroshi
    We investigated precise measurement methods for half-wavelength voltage, chirp paramter, extinction ratio of Mach-Zehnder modulators. Recently, very high extinction ratio over 70dB and ultra low chirp under 0.01 were achieved by using an active trimming technique. In addtion, precice and high-speed lighwave control or modulation would be very important in advanced modulation formats, such as 256 quadrature amplitude modulation., IEICE technical report, The Institute of Electronics, Information and Communication Engineers, IEICE technical report, 108(259)53 - 58, 16 Oct. 2008, Japanese
  • Fiber-wireless networks and radio-over-fibre technique
    Ken Ichi Kitayama, Toshiaki Kuri, J. J Vegas Olmos, Hiroyuki Toda
    Dense WDM access network of co-existing analog radio over fiber and digital FTTH systems is presented, by focusing on enabling techniques including optical frequency interleaving, supercontinuum light source, and optical channel allocation for wireless services. © 2008 IEEE., 2008 Conference on Quantum Electronics and Laser Science Conference on Lasers and Electro-Optics, CLEO/QELS, 15 Sep. 2008
  • Ultra high extinction-ratio and ultra low chirp optical intensity modulation for pure two-tone lightwave signal generation
    Tetsuya Kawanishi, Takahide Sakamoto, Akito Chiba, Masahiro Tsuchiya, Hiroyuki Toda
    Pure two-tone signal generation with spurious suppression ratio of 47 dB was demonstrated by using an optical Mach-Zehnder modulator with precisely balanced operation, where extinction ratio and chirp parameter were respectively 64 dB and 0.0099. © 2007 Optical Society of America., 2008 Conference on Quantum Electronics and Laser Science Conference on Lasers and Electro-Optics, CLEO/QELS, 15 Sep. 2008
  • Radio over fiber: DWDM-based analog/digital access networking and its enabling technologies
    Toshiaki Kuri, Hiroyuki Toda, Ken Ichi Kitayama
    Dense wavelength division multiplexed (DWDM) access network which allows to co-exists analog radio-over-fiber (RoF) and digital fiber-to-the-home (FTTH) systems is investigated. Focuses are on the enabling techniques such as optical-frequency-interleaved DWDM grid assignment, supercontinuum multi-wavelength light source, multi-band RoF and digital optical signals transmission, and optical path routing for dynamic channel allocation for wireless services. © 2008 IEEE., 2008 IEEE Radio and Wireless Symposium, RWS, 137 - 140, 09 Sep. 2008
  • Multi-Channel Crosstalk in a 25-GHz Spaced DWDM Millimeter-Wave-Band Radio-over-Fiber System
    YAMAGUCHI Takashi, TAKAHASHI Yoshitomo, TODA Hiroyuki, KURI Toshiaki, KITAYAMA Ken-ichi
    In this paper, we experimentally investigate the influence of multi-channel optical crosstalk in a 25-GHz spaced dense-wavelength division multiplexing (DWDM) millimeter-wave-band radio-over-fiber (RoF) downlink system. The eleven-channel crosstalk filtered with arrayed waveguide gratings (AWGs) was intentionally mixed with the desired channel of the RoF signal. We defined the suppression ratio of the crosstalk as the ratio of the mm-wave power of the desired channel and undesired channels which are estimated from optical spectrum of the detected RoF signal. The experimental results show that the power penalty due to the crosstalk of less than 1dB is obtained when the suppression ratio is more than 25dB., IEICE technical report, The Institute of Electronics, Information and Communication Engineers, IEICE technical report, 108(155)55 - 60, 17 Jul. 2008, English
  • Highly Pure 160-GHz Two-Tone Lightwave Generation using High Extinction-Ratio Optical Intensity Modulator and Delay Interferometer
    TODA Hiroyuki, MIYASHITA Junichi, CHIBA Akito, SAKAMOTO Takahide, KAWANISHI Tetsuya, TSUCHIYA Masahiro, IZUTSU Masayuki
    Quadruple two-tone lightwave of driving RF signal can be generated with a Mach-Zehnder modulator (MZM) operated at full-bias condition and an optical rejection filter to remove the output optical carrier. Recently, we reported that highly balanced operation of a high extinction-ratio MZM (HER-MZM) both optically and electrically is effective to suppress undesired even order optical sidebands for double sideband suppressed carrier modulation. In this report, we demonstrate highly pure quadruple two-tone lightwave generation with a highly balanced HER-MZM and a delay interferometer (DI). The highly balanced operation effectively suppresses undesired odd order sidebands, and the DI is effective to suppress 4th order sidebands. In 160-GHz two-tone lightwave generation experiment, the undesired sideband was suppressed by more than 39dB., IEICE technical report, The Institute of Electronics, Information and Communication Engineers, IEICE technical report, 108(155)65 - 67, 17 Jul. 2008, English
  • C-14-8 Influence of multi-channel crosstalk in 25-GHz Spaced DWDM Millimeter-Wave-Band Radio-over-Fiber System
    Takahashi Yoshitomo, Yamaguchi Takashi, Toda Hiroyuki, Kuri Toshiaki, Kitayama Ken-ichi
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2008(1), 05 Mar. 2008, Japanese
  • C-3-64 Quadruple RF generation using a high extinction-ratio optical modulator and a delayed interferometer
    Toda Hiroyuki, Miyashita Junichi, Kiuchi Hitoshi, Chiba Akito, Sakamoto Takahide, Kawanishi Tetsuya, Tsuchiya Masahiro, Izutsu Masayuki
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2008(1), 05 Mar. 2008, Japanese
  • Ultra high extinction-ratio and ultra low chirp optical intensity modulation for pure two-tone lightwave signal generation
    Tetsuya Kawanishi, Takahide Sakamoto, Akito Chiba, Masahiro Tsuchiya, Hiroyuki Toda
    Pure two-tone signal generation with spurious suppression ratio of 47 dB was demonstrated by using an optical Mach-Zehnder modulator with precisely balanced operation, where extinction ratio and chirp parameter were respectively 64 dB and 0.0099. © 2007 Optical Society of America., Optics InfoBase Conference Papers, 01 Jan. 2008
  • Fiber-wireless networks and radio-over-fibre technique
    Ken ichi Kitayama, Toshiaki Kuri, J. J. Vegas Olmos, Hiroyuki Toda
    Dense WDM access network of co-existing analog radio over fiber and digital FTTH systems is presented, by focusing on enabling techniques including optical frequency interleaving, supercontinuum light source, and optical channel allocation for wireless services. © 2008 OSA/CLEO/QELS 2008., Optics InfoBase Conference Papers, 01 Jan. 2008
  • B-10-72 A quadruple OTDM multiplier for RZ optical clock by means of stabilized delayed interferometers
    Miyashita Junichi, Adachi Yuki, Toda Hiroyuki
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2008, Japanese
  • Performance improvement of high-extinction-ratio LiNbO3optical intensity modulator by means of polarization crosstalk reduction
    Hiroyuki Toda, Katsuya Fukuta, Daisuke Arai, Akito Chiba, Kiyotaka Sasagawa, Tetsuya Kawanishi, Masahiro Tsuchiya, Masayuki Izutsu
    We demonstrate that dc extinction ratio can be improved by reducing polarization crosstalk in high-extinction-ratio LiNbO3optical intensity modulator. Observed improvement was more than 25 dB for the modulator used in the experiment. However, for double sideband suppressed carrier modulation, other factor limits carrier-to-sideband ratio. © 2007 IEEE., MWP 2007 - 2007 IEEE International Topical Meeting on Microwave Photonics, 191 - 193, 01 Dec. 2007
  • Radio over fiber: DWDM analog/digital access network and its enabling technologies
    Ken Ichi Kitayama, Toshiaki Kuri, Hiroyuki Toda, J. J Vegas Olmos
    Dense WDM access network which allows to co-exists analog radio over fiber and digital FTTH systems is investigated. Focuses are on the enabling techniques such as optical frequency interleaved DWDM grid assignment, supercontinuum light source, multi-band RoF and digital signals transmission, and optical path routing for dynamic channel allocation for wireless services. ©2007 IEEE., Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS, 794 - 795, 01 Dec. 2007
  • An effect of downlink optical sideband suppression on uplink transmission in full-duplex DWDM millimeter-wave-band radio-over-fiber
    Yoshitomo Takahashi, Kiyokazu Matsuba, Takahiro Sono, Susumu Sadoshima, Hiroyuki Toda, Toshiaki Kuri, Ken Ich Kitayama
    We quantitatively investigate an influence of residual downlink optical sideband on uplink transmission in full-duplex dense wavelength division multiplexed (DWDM) millimeterwave-band (mm-wave-band) radio-over-fiber (RoF) system. From our previous experiment, it was obtained that the influence was negligible when the undesired downlink sideband was suppressed by more than 20 dB. In this paper, we show the relationship between the downlink sideband suppression and the uplink transmission performance by numerical simulation, which was difficult to be scrutinized in practical experiment. © 2007 IEEE., MWP 2007 - 2007 IEEE International Topical Meeting on Microwave Photonics, 112 - 115, 01 Dec. 2007
  • C-14-13 An Effect of Downlink Optical Sideband Suppression on Uplink Transmission in Full-Duplex DWDM Millimeter-Wave-Band Radio-over-Fiber
    Takahashi Yoshitomo, Matsuba Kiyokazu, Sono Takahiro, Sadoshima Susumu, Toda Hiroyuki, Kuri Toshiaki, Kitayama Ken-ich
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 2007(1), 29 Aug. 2007, Japanese
  • C-3-61 Performance improvement of high-extinction-ratio LiNbO_3 optical intensity modulator by means of polarization crosstalk reduction : DSB-SC modulation characteristics
    Toda Hiroyuki, Chiba Akito, Sasagawa Kiyotaka, Kawanishi Tetsuya, Tsuchiya Masahiro, Izutsu Masayuki
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 2007(1), 29 Aug. 2007, Japanese
  • Performance improvement of high-extinction-ratio LiNbO_3 optical intensity modulator by means of polarization crosstalk reduction
    TODA Hiroyuki, FUKUTA Katsuya, ARAI Daisuke, CHIBA Akito, SASAGAWA Kiyotaka, KAWANISHI Tetsuya, TSUCHIYA Masahiro, IZUTSU Masayuki
    We demonstrate that dc extinction ratio can be improved by reducing polarization crosstalk in high-extinction-ratio LiNbO_3 optical intensity modulator. Observed improvement was more than 25 dB for the modulator used in the experiment. However, for double sideband suppressed carrier modulation, other factor limits carrier-to-sideband ratio., IEICE technical report, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OPE, 光エレクトロニクス, 107(173)175 - 178, 26 Jul. 2007, English
  • An Effect of Downlink Optical Sideband Suppression on Uplink Transmission in Full-Duplex DWDM Millimeter-Wave-Band Ratio-over-Fiber
    TAKAHASHI Yoshitomo, MATSUBA Kiyokazu, SONO Takahiro, SADOSHIMA Susumu, TODA Hiroyuki, KURI Toshiaki, KITAYAMA Ken-ich
    We quantitatively investigate an influence of residual downlink optical sideband on uplink transmission in full-duplex dense wavelength division multiplexed (DWDM) millimeter-wave-band (mm-wave-band) radio-over-fiber (RoF) system. From our previous experiment, it was obtained that the influence was negligible when the undesired downlink sideband was suppressed by more than 20 dB. In this paper, we show the relationship between the downlink sideband suppression and the uplink transmission performance by numerical simulation, which was difficult to be scrutinized in practical experiment., IEICE technical report, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OPE, 光エレクトロニクス, 107(173)121 - 126, 26 Jul. 2007, English
  • Novel Demultiplexing and Error-Free Transmission of 12-Channel 60-GHz-Band Signals in 25-GHz-Spaced DWDM Radio-over-Fiber System
    KURI Toshiaki, TODA Hiroyuki, KITAYAMA Ken-ichi
    We newly propose a simple wavelength demultiplexer for optical-frequency-interleaved dense wavelength division multiplexed (DWDM) radio-over-fiber (RoF) systems, which consists of only an optical coupler and a 2xN arrayed waveguide grating. The demultiplexing and transmission performance of twelve-channel 60-GHz-band DWDM RoF signals with 25-GHz channel spacing over 25-km plus 2-km standard single-mode fibers via the proposed demultiplexer is demonstrated. To the best of our knowledge, it is the first time that the error-free simultaneous transmission of 12-channel mm-wave-band RoF signals is demonstrated., IEICE technical report, The Institute of Electronics, Information and Communication Engineers, IEICE technical report, 107(173)127 - 130, 26 Jul. 2007, English
  • C-14-15 Effect of suppression of undesired downlink signal on uplink transmission in a full-duplex DWDM mm-wave-band radio-on-fiber system
    Sono Takahiro, Matsuba Kiyokazu, Takahashi Yoshitomo, Toda Hiroyuki, Kuri Toshiaki, Kitayama Ken-ichi
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2007(1), 07 Mar. 2007, Japanese
  • C-3-68 Performance improvement of high-extinction-ratio LiNbO_3 optical intensity modulator by means of polarization crosstalk reduction
    Toda Hiroyuki, Fukuta Katsuya, Arai Daisuke, Chiba Akito, Sasagawa Kiyotaka, Kawanishi Tetsuya, Tsuchiya Masahiro, Izutsu Masayuki
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2007(1), 07 Mar. 2007, Japanese
  • Novel demultiplexing and error-free transmission of 12-channel millimeter-wave-band signals in 25-GHz optical-frequency-interleaved DWDM radio-over-fiber system
    Toshiaki Kuri, Hiroyuki Toda, Ken Ichi Kitayama
    We demonstrate a novel demultiplexing and error-free transmission of twelve-channel 60-GHz-band signals over 25-km plus 2-km standard single-mode fibers in optical-frequency-interleaved dense wavelength division multiplexed radio-over-fiber system with 25-GHz channel spacing., 2007 33rd European Conference and Exhibition of Optical Communication, ECOC 2007, 01 Jan. 2007
  • Effect of downlink optical sideband suppression on uplink transmission in full-duplex DWDM millimeter-wave-band radio-over-fiber
    2007 INTERNATIONAL TOPICAL MEETING ON MICROWAVE PHOTONICS, 112 - +, 2007
  • B-10-18 Phase difference control between adjacent optical pulses by means of stabilization of delayed interferometer
    Miyashita Junichi, Toda Hiroyuki
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 2007, Japanese
  • 25-GHz-spacing optical-frequency-interleaved DWDM 60-GHz-band radio-on-fiber experiment using an sc light source and AWGs
    Yoshitomo Takahashi, Teppei Nakasyotani, Kiyokazu Matsuba, Hiroyuki Toda, Toshiaki Kuri, K. I. Kitayama
    We demonstrate 25-GHz-spacing optical-frequency-interleaved DWDM 60-GHz-band radio-on-fiber downlink experiment using an supercontinium light source and arrayed-waveguide gratings (AWGs). Filtering response of the AWGs is used for simultaneous suppression of undesired sidebands for all the channels., 2006 European Conference on Optical Communications Proceedings, ECOC 2006, (2)45 - 46, 01 Dec. 2006
  • Full-duplex 25-GHz spacing DWDM MM-wave-band radio-on-fiber system using a supercontinuum light source and arrayed-waveguide-grating filters
    Takahiro Sono, Yoshitomo Takahashi, Teppei Nakasyotani, Teppei Nakasyotani, Hiroyuki Toda, Toshiaki Kuri, Ken Ich Kitayama
    We demonstrate for the first time the full-duplex transmission of 25-GHz spacing dense wavelength-division multiplexing (DWDM) millimeter-wave-band radio-on-fiber (RoF) system using a supercontinuum (SC) light source and optical frequency interleaving technique. In the proposed scheme, filtering response of the arrayed waveguide gratings for demultiplexer and multiplexer is used for suppression of undesired optical sidebands. All the 25-GHz spacing SC modes are used for downlink transmission with photonic up-conversion. The uplink RoF signals are generated with photonic down-conversion from the reused downlink signals. The up- and downlinks 60-GHz-band 156-Mbps RoF signals were simultaneously transmitted over 25-km standard single-mode fibers with error-free and 0.5 dB power penalties., 2006 International Topical Meeting on Microwave Photonics, MWP, 19 , 01 Dec. 2006
  • B-10-28 25-GHz spacing mm-wave-band radio-on-fiber using a SC light source and AWGs : full-duplex experiment
    Sono Takahiro, Takahashi Yoshitomo, Nakashotani Teppei, Toda Hiroyuki, Kuri Toshiaki, Kitayama Ken-ich
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 2006(2), 07 Sep. 2006, Japanese
  • Dense multiplexing and transmission technique of millimeter-wave-band radio-on-fiber signals
    Toshiaki Kuri, Toshiaki Kuri, Hiroyuki Toda, Ken Ichi Kitayama
    Optical-frequency-interleaved dense wavelength division multiplexing (DWDM) transmission of millimeter-wave-band subcarrier-multiplexed (SCM) radio-on-fiber (RoF) signals with a photonic downconversion technique is described. The photonic downconversion technique is carried out for a lump of all multiplexed RoF signals at the receiver side. Error-free 25-GHz-spacing DWDM transmission and demultiplexing of two 60-GHz-band SCM RoF signals carrying 155-Mb/s differential phase-shift-keying data over 25-km-long standard single-mode fiber are experimentally demonstrated without serious fiber dispersion effect., Journal of the National Institute of Information and Communications Technology, 53(3)41 - 48, 01 Sep. 2006
  • 25-GHz-spacing optical-frequency-interleaved DWDM 60-GHz-band radio-on-fiber system using an SC light source and AWGs -- downlink experiment--
    Takahashi Yoshitomo, Nakasyotani Teppei, Matsuba Kiyokazu, Toda Hiroyuki, Kuri Toshiaki, Kitayama Ken-ichi
    In this paper, we demonstrate 25-GHz-spacing optical-frequency-interleaved DWDM 60-GHz-band radio-on-fiber (RoF) downlink experiment using an supercontinium (SC) light source and arrayed-waveguide gratings (AWGs). Three AWGs are used for multiplexing/demultiplexing the SC modes. In our proposed scheme, filtering response of the AWGs is effectively used for simultaneous suppression of undesired sidebands to avoid the interchannel interference. All the 25-GHz spacing SC modes are used for downlink transmission with photonic up-conversion. Three-channel 60-GHz band RoF signals were simultaneously transmitted over 25-km standard single-mode fiber with error-free and no noticeable power penalty., IEICE technical report, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告, 106(186)21 - 24, 27 Jul. 2006, English
  • 25GHz Spacing Optical-Frequency-Interleaved DWDM 60-GHz-Band Radio-on-Fiber System Using an SC light source and AWGs : Full-Duplex Experiment
    SONO Takahiro, TAKAHASHI Yoshitomo, NAKASHOTANI Teppei, TODA Hiroyuki, KURI Toshiaki, KITAYAMA Ken-ichi
    We demonstrate for the first time the full-duplex transmission of 25-GHz spacing dense wavelength-division multiplexing (DWDM) millimeter-wave-band radio-on-fiber (RoF) system using a supercontinuum (SC) light source and optical frequency interleaving technique. In the proposed scheme, filtering response of the arrayed waveguide gratings for demultiplexing and multiplexing is used for suppression of undesired optical sidebands. All the 25-GHz spacing SC modes are used for downlink transmission with photonic up-conversion. The uplink RoF signals are generated with photonic down-conversion from the reused downlink signals. The up- downlinks 60-GHz-band 156-Mbps RoF signals were simultaneously transmitted over 25-km standard single-mode fibers with error-free and 0.5 dB power penalty., IEICE technical report, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OPE, 光エレクトロニクス, 106(187)15 - 19, 20 Jul. 2006, Japanese
  • 25-GHz-Spacing Optical-Frequency-Interleaved DWDM 60-GHz-Band Radio-on-Fiber System Using an SC light source and AWGs : Downlink Experiment
    TAKAHASHI Yoshitomo, NAKASYOTANI Teppei, MATSUBA Kiyokazu, TODA Hiroyuki, KURI Toshiaki, KITAYAMA Ken-ichi
    In this paper, we demonstrate 25-GHz-spacing optical-frequency-interleaved DWDM 60-GHz-band radio-on-fiber (RoF) downlink experiment using an supercontinium (SC) light source and arrayed-waveguide gratings (AWGs). Three AWGs are used for multiplexing/demultiplexing the SC modes. In our proposed scheme, filtering response of the AWGs is effectively used for simultaneous suppression of undesired sidebands to avoid the interchannel interference. All the 25-GHz spacing SC modes are used for downlink transmission with photonic up-conversion. Three-channel 60-GHz band RoF signals were simultaneously transmitted over 25-km standard single-mode fiber with error-free and no noticeable power penalty., IEICE technical report, The Institute of Electronics, Information and Communication Engineers, IEICE technical report, 106(187)21 - 24, 20 Jul. 2006, English
  • C-14-14 A 25GHz Spacing DWDM Millimeter-Wave-Band Radio-on-Fiber System Using an SC light source and AWGs
    Takahashi Yoshitomo, Nakasyotani Teppei, Matsuba Kiyokazu, Toda Hiroyuki, Kuri Toshiaki, Kitayama Ken-ichi
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2006(1), 08 Mar. 2006, Japanese
  • Full-duplex 25-GHz spacing DVMM NIM-wave-band radio-on-fiber system using a supercontinuum light source and arrayed-waveguide-grating filters
    2006 INTERNATIONAL TOPICAL MEETING ON MICROWAVES PHOTONICS, 247 - +, 2006
  • A full-duplex WDM millimeter-wave-band radio-on-fiber system using a supercontinuum light source
    Hiroyuki Toda, Teppei Nakasyotani, Toshiaki Kuri, Ken Ichi Kitayama
    We demonstrate a full-duplex WDM millimeter-wave-band radio-on-fiber (RoF) system using a supercontinuum (SC) light source. For downlink transmission, the periodic nature of arrayed waveguide grating, where the period is free spectral range, Is used for utilizing the full bandwidth of the SClight source. Half of the SC output modes are used for uplink transmission with photonic downconversion. These techniques are effective to use a wealth of optical frequency resources from the SC light source. Two-channel downlink and one-channel uplink 60-GHz band RoF signals were simultaneously transmitted over 25-km standard single-mode fiber with error-free and no noticeable power penalty., International Topical Meeting on Microwave Photonics, MWP 2005, T3(5)111 - 114, 01 Dec. 2005
  • 60- And 2.4-GHz dual-band wavelength-division-multiplexed radio-on-fiber system using A supercontinuum light source
    Toshiaki Kuri, Teppei Nakasyotani, Hiroyuki Toda, Ken Ichi Kitayama
    A wavelength-division-multiplexed transmission of dual-band radio-on-fiber signals using a supercontinuum light source is proposed. Error-free photonic up-conversion operation and simultaneous fiber-optic transmissions of 2.45-GHz- and 60-GHz-band signals using the dual-band compact base station prototype are demonstrated., International Topical Meeting on Microwave Photonics, MWP 2005, T1(3)55 - 58, 01 Dec. 2005
  • DWDM millimeter-wave radio-on-fiber systems
    Hiroyuki Toda, Toshiaki Kuri, Ken Ichi Kitayama
    We describe some of our recent results on DWDM mm-wave radio-on-fiber (RoF) technology for future broadband wireless systems. A supercontinuum (SC) light source is a promising multiwavelength light source for the system with photonic up-conversion. Multiplexing and demultiplexing schemes for optical frequency interleaving in order to extend the number of antenna base stations can be constructed using a properly designed arrayed-waveguide grating (AWG). We demonstrate a full-duplex WDM mm-wave RoF system using a SC light source. The periodic nature of AWG, where the period is free spectral range (FSR), is used for utilizing the full bandwidth of the SC light source. Half of the SC output modes are used for downlink transmission with photonic upconversion. Another half of the SC output modes are used for uplink transmission with photonic downconversion. These techniques are effective to use a wealth of optical frequency resources from the SC light source. Two-channel downlink and one-channel uplink 60-GHz band RoF signals were simultaneously transmitted over 25-km standard single-mode fiber with error-free and no noticeable power penalty., Proceedings of SPIE - The International Society for Optical Engineering, 6021 I, 01 Dec. 2005
  • C-14-6 Experiment of a Full-Duplex WDM Millimeter-Wave-Band Radio-on-Fiber System Using a Supercontinuum Light Source
    NAKASYOTANI Teppei, TODA Hiroyuki, KURI Toshiaki, KITAYAMA Ken-ichi
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 2005(1), 07 Sep. 2005, Japanese
  • Evaluation of photonic downconversion of millimeter-wave-band radio-on-fiber signal using a supercontinuum light source
    KURI Toshiaki, NAKASYOTANI Teppei, TODA Hiroyuki, KITAYAMA Ken-ichi
    In wavelength-division-multiplexed millimeter-wave-band radio-on-fiber systems using a supercontinuum (SC) light source, we propose using the mode frequency interval for the photonic down-conversion method positively as a reference of frequency conversion paying attention to the stability of the mode interval of the optical frequency components generated from the SC light source. In order to investigate the performance of the technique, we evaluate the phase-noise characteristics of photonic-downconverted signal. Moreover, its error-free operation is demonstrated by measuring a bit error rate of 155-Mb/s data transmission to show the usefulness of the proposed technique., Technical report of IEICE. OPE, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OPE, 光エレクトロニクス, 105(182)35 - 38, 07 Jul. 2005, English
  • WDM millimeter-wave-band radio-on-fiber systems using a supercontinuum light source-- Demultiplexing experiment of WDM channels using a free spectral range of AWG --
    NAKASYOTANI Teppei, TODA Hiroyuki, KURI Toshiaki, KITAYAMA Ken-ichi
    We have proposed the use of a supercontinuum (SC) light source in wavelength-division-multiplexed (WDM) millimeter-wave-band (mm-wave-band) radio-on-fiber (RoF) systems. In this report, we investigate a demultiplexing technique of WDM channels effectively using a free spectral range (FSR) of arrayed-waveguide-grating (AWG) in a remote node of the WDM mm-wave-band RoF system. The delivery of 2-channel WDM 60-GHz-band RoF signals transmitted over a 25-km-long standard single-mode fiber (SMF) is experimentally demonstrated utilizing AWG with the FSR of 0.8-THz., Technical report of IEICE. OPE, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OPE, 光エレクトロニクス, 105(182)13 - 16, 07 Jul. 2005, English
  • Characterizations of supercontinuum light source for WDM millimeter-wave-band radio-on-fiber systems
    Toshiaki Kuri, Teppei Nakasyotani, Hiroyuki Toda, Ken Ichi Kitayama
    We qualitatively evaluate for the first time phase-noise characteristics of radio-frequency carriers of a supercontinuum generator and prove to be promising as the multiwavelength light source for wavelength-division-multiplexed millimeter-wave-band radio-on-fiber systems. © 2005 IEEE., IEEE Photonics Technology Letters, 17(6)1274 - 1276, 01 Jun. 2005
  • CS-11-6 WDM Millimeter-Wave-Band Radio-on-Fiber System Using a Supercontinuum Light Source : Effective Use of Optical Frequency Resource with a Free Spectral Range of AWG
    NAKASYOTANI Teppei, TODA Hiroyuki, KURI Toshiaki, KITAYAMA Ken-ichi
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2005(1)"S - 63", 07 Mar. 2005, Japanese
  • Error-free operation of photonic downconversion for millimeter-wave-band uplink radio-on-fiber systems using a supercontinuum light source
    Toshiaki Kuri, Teppei Nakasyotani, Hiroyuki Toda, Ken Ichi Kitayama
    In wavelength-division-multiplexed millimeter-wave-band radio-on-fiber systems using a supercontinuum (SC) light source, we evaluate the phase-noise characteristics of photonic-downconverted signal, where the SC-mode interval frequency is utilized for the local reference, and demonstrate its error-free operation., IET Conference Publications, Th2(3)859 - 860, 01 Jan. 2005
  • A compact remote antenna base station for microwave/millimeter-wave dual-band radio-on-fiber systems
    Toshiaki Kuri, Kensuke Ikeda, Hiroyuki Toda, Ken Ichi Kitayama, Yoshiro Takahashi
    A compact prototype of dual-band base station (BS) for use in the dual band radio-on-fiber (RoF) systems, to realize the dual-band ROF transmission, is described. An error-free simultaneous fiber-optic transmission of 2.45-GHz and 60-GHz-band signals with the dual-band BS prototype is also described. The dual-band BS covers two service areas by using microwave and mm-wave band signals, and consists of a high-speed photodetector (PD) with the 3-dB bandwidth of 60 GHz. A pair of down and uplink optical carriers with different wavelengths must be individually assigned to each dual-band BS to successfully perform the wavelength division multiplexing (WDM) ROF transmission., Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS, MF359 - 60, 01 Dec. 2004
  • WDM mm-wave-band radio-on-fiber system using single supercontinuum light source in cooperation with photonic up-conversion
    Hiroyuki Toda, Teppei Nakasyotani, Toshiaki Kuri, Ken Ichi Kitayama
    We propose to use a supercontinuum light source for WDM millimeter-wave-band radio-on-fiber (ROF) systems. 2-channel WDM 60-GHz-band ROF signals are generated and transmitted over 25-km standard single mode fiber using a photonic up-conversion technique. © 2004 IEEE., IEEE International Topical Meeting on Microwave Photonics - Technical Digest, MWP, TA(2)161 - 164, 01 Dec. 2004
  • Potential light source of super-continuum wavelength-division-multiplexed millimeter-wave-band radio-on-fiber system
    Toshiaki Kuri, Teppei Nakasyotani, Hiroyuki Toda, Ken Ichi Kitayama
    In a novel wavelength-division-multiplexed millimeter-wave-band radio-on-fiber system using a super-continuum light source as the multi-wavelength light source, we qualitatively evaluate for the first time the phase-noise characteristics of radio-frequency carriers and prove to be promising. © 2004 IEEE., IEEE International Topical Meeting on Microwave Photonics - Technical Digest, MWP, MC(2)40 - 43, 01 Dec. 2004
  • A compact base station prototype for dual-band radio-on-fiber transmission systems
    KURI Toshiaki, IKEDA Kensuke, TODA Hiroyuki, TAKAHASHI Yoshiro, KITAYAMA Ken-ichi
    In order to realize the dual-band radio-on-fiber (ROF) transmission, which means that microwave- and mm-wave-band radio signals are simutaneously transmitted in an optical fiber link, we made the practically compact prototype of dual-band base station (BS) for use in the dual-band ROF systems. We experimentally demonstrate an error-free simultaneous fiber-optic transmission of a 60-GHz-band 155-Mb/s-DPSK signal with a 2.45-GHz sinusouidal wave by using the dual-band BS prototype., Technical report of IEICE. OCS, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OCS, 光通信システム, 104(456)73 - 76, 25 Nov. 2004, English
  • Feasibility of a supercontinuum light source for DWDM mm-wave-band radio-on-fiber systems
    NAKASYOTANI Teppei, TODA Hiroyuki, KURI Toshiaki, KITAYAMA Ken-ichi
    We propose to use a supercontinuum light source for WDM millimeter-wave-band radio-on-fiber (ROF) systems. We demonstrate the generation of single channel 60-GHz-band ROF signal and transmission of the signal over 25-km standard single mode fiber (SMF) using a photonic up-conversion. We also demonstrate the generation of 2-channel WDM 60-GHz-band ROF signals and transmission of the signals over 25-km SMF., Technical report of IEICE. OCS, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OCS, 光通信システム, 104(456)67 - 72, 25 Nov. 2004, English
  • C-14-5 Feasiblity Study of WDM mm-wave Radio-on-Fiber System Using Supercontinuum Light Source
    NAKASHOTANI Teppei, KURI Toshiaki, IKEDA Kensuke, TODA Hiroyuki, KITAYAMA Ken-ichi
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2004(1), 08 Mar. 2004, Japanese
  • C-14-4 A Consideration on the Use of Super-Continuum Light Source for Millimeter-Wave-Band Radio-on-Fiber Systems
    KURI Toshiaki, NAKASYOTANI Teppei, IKEDA Kensuke, TODA Hiroyuki, KITAYAMA Ken-ichi
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2004(1), 08 Mar. 2004, English
  • High-spectral density multiplexing transmission and photonic mixing for millimeter-wave-band radio-on-fiber systems
    Toshiaki Kuri, Tsukasa Yamashita, Tsukasa Yamashita, Hiroyuki Toda, Ken Ichi Kitayama
    Two system architectures based on dense wavelength division multiplexing (DWDM) for millimeter-wave-band (mm-wave-band) radio-on-fiber (ROF) systems are described. One architecture consists of a wavelength multiplexer and demultiplexer with arrayed waveguide gratings (AWGs) for optical-frequency- interleaved DWDM ROF transmission. The other architecture is based on a photonic down-conversion technique that is used in DWDM ROF systems. A 25-GHz-spaced, 60-GHz-band DWDM ROF transmission with photonic down-conversion is experimentally demonstrated., Journal of the National Institute of Information and Communications Technology, 51(1)133 - 139, 01 Mar. 2004
  • Distributed PMD compensation experiment using polarizers
    TODA Hiroyuki, NARA Masaki, MATSUMOTO Masayuki, ALZETTA Daniele
    We report experimental results on polarization mode dispersion (PMD) compensation by distributing linear polarizers along the transmission line. Polarizers are used as PMD compensator elements with only 1 degree-of-freedom which result in simple configuration for a PMD compensator. In the experiment, the average power penalty was 0.4 dB by inserting four compensators, where average differential group delay (DGD) was 47 % of the bit period., Technical report of IEICE. OCS, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OCS, 光通信システム, 103(627)27 - 30, 23 Jan. 2004, English
  • Dense wavelength-division-multiplexing millimeter-wave-band radio-on-fiber systems
    Toshiaki Kuri, Hiroyuki Toda, Ken Ichi Kitayama
    Two types of dense wavelength division multiplexing (DWDM) millimeter-wave-band radio-on-fiber (ROF) system architectures are presented. As such, focus is made on its multiplexing and demultiplexing techniques and its photonic down conversion (PDC) scheme., Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS, 2863 - 864, 09 Dec. 2003
  • Distributed PMD compensation experiment using rotatable polarizers
    Toda Hiroyuki, Nara Masaki, Matsumoto Masayuki, Alzetta Daniele
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 2003(2), 10 Sep. 2003, Japanese
  • Optical-Frequency-Interleaved DWDM Transmission of Millimeter-Wave-Band SCM Radio-on-Fiber Signals
    KURI Toshiaki, TODA Hiroyuki, KITAYAMA Ken-ichi
    In this report, optical-frequency-interleaved dense wavelength division multiplexing (DWDM) transmission of mm-wave-band subcarrier-multiplexed (SCM) radio-on-fiber (ROF) signals is investigated and experimentally demonstrated. In the experiment, 2-channel-DWDM/2-channel-SCM ROF signal is transmitted over 25-km-long standard single-mode optical fiber (SMF) and demultiplexed. The multiplexed signal consists of independent four 60-GHz-band 155.52-Mb/s-DPSK ROF signals. To our knowledge, it will be the first experimental demonstration of multi-channel fiber-optic transmission simultaneously with both interleaved DWDM and SCM techniques., Technical report of IEICE. OPE, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OPE, 光エレクトロニクス, 103(240)29 - 32, 31 Jul. 2003, English
  • Optical frequency-interleaved DWDM multiplexing using an arrayed wavegudie grating for mm-wave-band radio-on-fiber systems
    TODA Hiroyuki, YAMASHITA Tsukasa, KURI Toshiaki, KITAYAMA Ken-ichi
    We demonstrate an optical frequency-interleaved dense wavelength division multiplexing (DWDM) multiplexing scheme using an arrayed-waveguide grating for mm-wave band radio-on-fiber (ROF) systems. The scheme allows us to filter out undesired sidebands and to simultaneously enhance the modulation indices of the multiplexed ROF signals. No noticeable power penalty was observed due to 25-km SMF transmission and interchannel interference. The receiver sensitivity was improved by 6 dB by increasing the modulation index of the ROF signal., Technical report of IEICE. OPE, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OPE, 光エレクトロニクス, 103(240)25 - 28, 31 Jul. 2003, English
  • A multiplexing scheme using an arrayed-waveguide grating for optical frequency interleaved DWDM mm-wave fiber-radio system
    Yamashita Tsukasa, Toda Hiroyuki, Kawasaki Zen, Kuri Toshiaki, Kitayama Kenichi
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2003(1), 03 Mar. 2003, Japanese
  • C-14-6 A Consideration on Nonlinear Effect of Frequency Shifter in Photonic Downconversion for DWDM ROF Systems
    KURI Toshiaki, TODA Hiroyuki, KITAYAMA Kenichi
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2003(1), 03 Mar. 2003, English
  • 25-GHz channel spacing DWDM multiplexing using an arrayed waveguide grating for 60-GHz band radio-on-fiber systems
    Hiroyuki Toda, Tsukasa Yamashita, Toshiaki Kuri, Ken Ichi Kitayama
    We propose and demonstrate a DWDM multiplexing scheme using an arrayed-waveguide grating for optically frequency interleaved 60-GHz band radio-on-fiber systems. No noticeable power penalty was observed after 25-km SMF transmission when the channel spacing was 25 GHz., MWP 2003 - Proceedings, International Topical Meeting on Microwave Photonics, 287 - 290, 01 Jan. 2003
  • Demultiplexing using an arrayed-waveguide grating for frequency-interleaved DWDM radio-on-fiber systems with 25-GHz channel spacing
    Hiroyuki Toda, Tsukasa Yamashita, Ken Ichi Kitayama, Toshiaki Kuri
    We experimentally demonstrate a demultiplexing scheme for the frequency-interleaved dense wavelength division multiplexing (DWDM) radio-on-fiber system using an arrayed-waveguide grating (AWG). We first show the principle of the frequency-interleaved DWDM radio-on-fiber and possible configurations of multiplexing and demultiplexing (DEMUX) schemes using an AWG. In the experiment, 25-GHz separated 2-channel optical double sideband signals modulated by a 60-GHz millimeter-wave carrying a 156 Mbps data are optically multiplexed by frequency interleaving. The power penalty after DEMUX, which was due to interchannel interference, was less than 0.5 dB. We also made a transmission experiment in 25-km standard single mode fiber (SMF). No noticeable power penalty in the received data due to transmission was observed. This is because carrier and only one of the sidebands are detected in the proposed DEMUX scheme., Proceedings of SPIE - The International Society for Optical Engineering, 4906(20)99 - 106, 31 Dec. 2002
  • Photonic downconversion with optical frequency shift for dense WDM radio-on-fiber signals
    Toshiaki Kuri, Hiroyuki Toda, Ken Ichi Kitayama
    The PDC technique with optical frequency shift for DWDM mm-wave-band ROF signal was developed. The 25-km-long SMF transmission adopting the PDC technique was experimentally demonstrated without serious laser phase noise, fiber-dispersion effect, and inter-channel interference., Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS, WN2473 - 474, 01 Dec. 2002
  • Design process for fiber-optic bi-soliton transmission line
    TOMITA Takahiro, TODA Hiroyuki, KAWASAKI Zen
    The bi-soliton recently discovered by numerical simulation is a pair of nonlinear optical pulses transmitting through a loss-less dispersion management fiber, where the pulse interval is kept to be constant. If the transmission fiber is lossy, the dispersion management line should be constracted by dispersion decreased fibers. In this paper, we will introduce a designing process of the transmission line for bi-soliton constracted by commercially available fibers for more realistic line. Then, we will present the required tolerance of the group velocity dispersion of the fibers and its compensation., Technical report of IEICE. OPE, The Institute of Electronics, Information and Communication Engineers, Technical report of IEICE. OPE, 102(448)25 - 30, 07 Nov. 2002, Japanese
  • Photonic Downconversion Scheme for Dense Wavelength Division Multiplexing Radio-on-Fiber Systems
    KURI Toshiaki, TODA Hiroyuki, KITAYAMA Ken-ichi
    In this report, photonic downconversion (PDC) technique for dense wavelength division multiplexing (DWDM) millimeter-wave-band radio-on-fiber (ROF) systems is proposed. The PDC technique is carried out for a lump of all uplink WDM ROF signals. Each channel is optically separated, frequency-shifted, selected, photodetected, and demodulated individually without serious signal degradation due to the fiber dispersion effect and the laser phase noise. Error-free 25-GHz-spaced WDM transmission and demultiplexing of two 60-GHz-band, 155-Mb/s-DPSK ROF signals over 25-km-long standard single-mode fiber are experimentally demonstrated., Technical report of IEICE. OCS, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OCS, 光通信システム, 102(358)67 - 72, 02 Oct. 2002, English
  • Demultiplexing experiment using arrayed waveguide grating for optical frequency interleaved DWDM mm-wave fiber-radio systems
    YAMASHITA Tsukasa, TODA Hiroyuki, KAWASAKI Zen, KURI Toshiaki, KITAYAMA Ken-ichi
    In this report, we experimentally demonstrate demultiplexing 25-GHz separated 2-channel optical DSB signals modulated by a 60-GHz mm-wave carrying a 156-Mbps-DPSK data using an arrayed-waveguide grating (AWG) for DWDM mm-wave fiber-radio systems by optical frequency interleaving. The configuration of demultiplexer consists of a high-finesse Fabry-Perot etalon, the AWG with 2-input and N-output waveguides and an optical circulator. The power penalty after demultiplexing channels 1 and 2 were less than 0.5 dB. No noticeable power penalty was observed after 25-km SMF transmission. This is because the carrier and only one of the sidebands are detected in the proposed demultiplexing scheme., Technical report of IEICE. OCS, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OCS, 光通信システム, 102(358)61 - 66, 02 Oct. 2002, English
  • Demultiplexing experiment using an arrayed waveguide grating for optical frequenecy interleaved DWDM mm-wave radio-on-fiber systems
    Yamashita Tsukasa, Toda Hiroyuki, Kawasaki Zen, Kuri Toshiaki, Kitayama Ken-ichi
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 2002(1), 20 Aug. 2002, Japanese
  • C-14-12 Photonic Downconversion Technique for Dense WDM Millimeter-Wave-Band Radio-on-Fiber Signals
    KURI Toshiaki, TODA Hiroyuki, KITAYAMA Ken-ichi
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 2002(1), 20 Aug. 2002, English
  • Conference Report on Microwave Photonics 2001
    NAGATSUMA Tadao, HIRATA Akihiko, KURI Toshiaki, TODA Hiroyuki
    2001 International Topical Meeting on Microwave Photonics (MWP200l) was held at Long Beach, California in January 7 9, 2002. This paper reports the overview of the conference, summarizing almost all the papers presented., Technical report of IEICE. OPE, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OPE, 光エレクトロニクス, 102(126)41 - 48, 13 Jun. 2002, Japanese
  • Reduction of pulse-to-pulse interaction of optical RZ pulses in dispersion managed fiber
    Hiroyuki Toda, Shoji Kobayashi, Ippei Akiyoshi
    When closely temporally separated two optical pulses of identical wavelength are transmitted in optical fiber, the pulse separation could be changed due to nonlinear effect. We evaluate the pulse-to-pulse interaction in dense dispersion management by simulation and experiment. First, we evaluate the influence of third order dispersion on the pulse-to-pulse interaction by numerical simulation of transmission. The interaction can be effectively reduced when dispersion shifted fiber for dispersion slope tuning is placed at input of EDFA repeaters. Then we performed a recirculating loop transmission experiment of 3.5-ps optical RZ pulses with 12.5-ps initial separation in dispersion flattened dispersion-managed fiber. The interaction can be greatly reduced by employing dense dispersion managed fiber, which is favorable for ultra-high speed OTDM transmission systems., Proceedings of SPIE - The International Society for Optical Engineering, 4906(54)267 - 272, 01 Jan. 2002
  • Dwdm demultiplexing with 25-GHz channel spacing for 60-GHz band radio-on-fiber systems
    Hiroyuki Toda, Tsukasa Yamashita, Ken Ichi Kitayama, Toshiaki Kuri
    © 2002 DTU. We experimentally demonstrate demultiplexing using an arrayed-waveguide grating for a DWDM mm-wave fiber-radio system by optical frequency interleaving. No noticeable power penalty was observed after 25-km SMF transmission when the channel separation was 25 GHz., European Conference on Optical Communication, ECOC, 3, 01 Jan. 2002
  • 1.5 Tbit/s (75 × 20 Gbit/s) DWDM transmission using Er3+-doped tellurite fiber amplifiers and a single otdm demultiplexing scheme
    Hiroyuki Toda, Maoki Suzuki, Ryo Takami, Hideyuki Sotobayashi, Tetsuya Miyazaki, Takeshi Makino, Jun Inoue, Wataru Chujo
    1.5 Tbit/s (75 × 20 Gbit/s) DWDM transmission with 61 nm continuous bandwidth over 200 km was successfully demonstrated by employing Er3+-doped tellurite fiber amplifiers and a single OTDM demultiplexing scheme using injection locking mode-locked laser diode for subharmonic optical clock recovery., European Conference on Optical Communication, ECOC, 2, 01 Jan. 2002
  • 25-GHz channel spacing DWDM demultiplexing for 60-GHz band radio-on-fiber systems using an arrayed waveguide grating
    H. Toda, T. Yamashita, K. I. Kitayama, T. Kuri, T. Kuri
    © 2002 IEEE. We experimentally demonstrate demultiplexing using an arrayed-waveguide grating for a DWDM mm-wave radio-on-fiber system by optical frequency interleaving. No noticeable power penalty was observed after 25 km SMF transmission when the channel spacing was 25 GHz., 2002 International Topical Meeting on Microwave Photonics, MWP 2002 - Technical Digest, 33 - 36, 01 Jan. 2002
  • Photonic Downconversion Scheme for Dense Wavelength Division Multiplexing Radio-on-Fiber Systems
    KURI Toshiaki, TODA Hiroyuki, KITAYAMA Ken-ichi
    In this report, photonic downconversion (PDC) technique for dense wavelength division multiplexing (DWDM) millimeter-wave-band radio-on-fiber (ROF) systems is proposed. The PDC technique is carried out for a lump of all uplink WDM ROF signals. Each channel is optically separated, frequency-shifted, selected, photodetected, and demodulated individually without serious signal degradation due to the fiber dispersion effect and the laser phase noise. Error-free 25-GHz-spaced WDM transmission and demultiplexing of two 60-GHz-band, 155-Mb/s-DPSK ROF signals over 25-km-long standard single-mode fiber are experimentally demonstrated., ITE Technical Report, The Institute of Image Information and Television Engineers, ITE Technical Report, 26(0)67 - 72, 2002, English
  • Demultiplexing experiment using arrayed waveguide grating for optical frequency interleaved DWDM mm-wave fiber-radio systems
    YAMASHITA Tsukasa, TODA Hiroyuki, KAWASAKI Zen, KURI Toshiaki, KITAYAMA Ken-ichi
    In this report, we experimentally demonstrate demultiplexing 25-GHz separated 2-channel optical DSB signals modulated by a 60-GHz mm-wave carrying a 156-Mbps-DPSK data using an arrayed-waveguide grating (AWG) for DWDM mm-wave fiber-radio systems by optical frequency interleaving. The configuration of demultiplexer consists of a high-finesse Fabry-Perot etalon, the AWG with 2-input and N-output waveguides and an optical circulator. The power penalty after demultiplexing channels 1 and 2 were less than 0.5 dB. No noticeable power penalty was observed after 25-km SMF transmission. This is because the carrier and only one of the sidebands are detected in the proposed demultiplexing scheme., ITE Technical Report, The Institute of Image Information and Television Engineers, ITE Technical Report, 26(0)61 - 66, 2002, English
  • A DWDM mm-wave fiber-radio system with optical frequency interleaving
    YAMASHITA Tsukasa, TODA Hiroyuki, KAWASAKI Zen, KURI Toshiaki, KITAYAMA Ken-ichi
    We propose a DWDM mm-wave fiber-radio system with optical frequency interleaving for high spectral efficiency. In this paper, we show preliminary experimental result that 2-channel optical DSB signals carrying 60 GHz mm-waves, multiplexed by optical frequency interleaving are demultiplexed. We obtain error-free operation (BER<10^<-10>) with the channel separation of only 10 GHz. We also show theoretical analysis of power penalty due to interchannel crosstalk., Technical report of IEICE. OCS, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OCS, 光通信システム, 101(283)19 - 24, 31 Aug. 2001, English
  • Influence of Dispersion Slope on Dense Dispersion Managed Soliton Transmission
    Akiyoshi Ippei, Toda Hiroyuki, Kawasaki Zen
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 2001(2), 29 Aug. 2001, Japanese
  • Proposal of a DWDM mm-wave fiber-radio system with optical frequency interleaving
    Yamashita Tsukasa, Toda Hiroyuki, Kawasaki Zen, Kuri Toshiaki, Kitayama Ken-ichi
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 2001(1), 29 Aug. 2001, Japanese
  • Receiver sensitivity of optical RZ receiver using nonlinearity in normal dispersion fiber
    Suzuki Maoki, Takami Ryo, Toda Hiroyuki
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 2001(2), 07 Mar. 2001, Japanese
  • A DWDM MM-wave fiber-radio system by optical frequency interleaving for high spectral efficiency
    H. Toda, T. Yamashita, K. Kitayama, T. Kuri
    © 2001 IEEE. We propose a simple method for fully utilizing optical bandwidth of DWDM millimeter-wave fiber-radio systems by optical frequency interleaving. Preliminary experiment with the channel separation of only 10 GHz showed the interchannel-crosstalk induced power penalty of 2.7 dB., 2001 International Topical Meeting on Microwave Photonics, MWP 2001, 185 - 88, 01 Jan. 2001
  • Q-factor improvement in a jitter limited optical RZ system using nonlinearity of normal dispersion fiber placed at receiver
    M. Suzuki, H. Toda
    We adopted a new detection scheme using nonlinearity of normal dispersion fiber in a jitter limited 10 Gb/s soliton transmission. The obtained amplitude margin at BER of 10-9 was three times larger than the conventional scheme., Conference on Optical Fiber Communication, Technical Digest Series, 54, 01 Jan. 2001
  • A DWDM mm-wave fiber-radio system with optical frequency interleaving
    Yamashita Tsukasa, Toda Hiroyuki, Kawasaki Zen, Kuri Toshiaki, Kitayama Ken-ichi
    We propose a DWDM mm-wave fiber-radio system with optical frequency interleaving for high spectral efficiency. In this paper, we show perliminary experimental result that 2-channel optical DSB signals carrying 60GHz mm-waves, multiplexed by optical frequency interleaving are demultiplexed. We obtain error-free operation (BER<10^<-10>) with the channel separation of only 10GHz. We also show theoretical analysis of power penalty due to interchannel crosstalk., ITE Technical Report, The Institute of Image Information and Television Engineers, ITE Technical Report, 25(0)19 - 24, 2001, English
  • Improvement of a phase margin in optical RZ receiver using nonlinearity in normal dispersion fiber : experimental verification
    Suzuki Maoki, Toda Hiroyuki, Liang Anhui, Hasegawa Akira
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 2000(2), 07 Sep. 2000, Japanese
  • Improvement of a phase margin in optical RZ receiver using nonlinearity in normal dispersion fibers : experimental verification
    SUZUKI Maoki, TODA Hiroyuki, LIANG Anhui, HASEGAWA Akira
    We propose a new technique to expand the phase margin of an optical RZ receiver by utilizing Kerr nonlinearity in normal dispersion fibers. We carried out a numerical simulations and confirmed that the proposed method is more effective than a Bessel-Thompson filter in reducing the influence of timing jitter caused by soliton interaction and Gordon-Haus effect. We also adapted this technique to the 10 Gbps optical soliton pulses transmitted over 16, 000 km in a sliding frequency recirculating loop. The phase and amplitude margins obtained with the proposed method were 57% and 22% wider than that with the filter with 7.5 GHz bandwidth., Technical report of IEICE. OCS, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OCS, 光通信システム, 100(92)13 - 18, 19 May 2000, Japanese
  • Improvement of a phase margin in optical RZ receiver using nonlinearity in normal dispersion fiber
    Suzuki Maoki, Toda Hiroyuki, Liang Anhui, Hasegawa Akira
    Proceedings of the IEICE General Conference, 一般社団法人電子情報通信学会, 電子情報通信学会総合大会講演論文集, 2000(2), 07 Mar. 2000, Japanese
  • An Optical Packet Compressor using a Fiber Loop
    Suzuki Maoki, Nakada Fumitoshi, Toda Hiroyuki, Hasegawa Akira
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 1999(2), 16 Aug. 1999, Japanese
  • High Speed Optical Transmission with Dense Dispersion Managed Soliton
    Yamaguchi Naoki, Toda Hiroyuki, Hasegawa Akira
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 1999(2), 16 Aug. 1999, Japanese
  • Experimental Evaluation of Timing Jitter of Dispersion Managed Solitons
    HAMADA Kazunori, TODA Hiroyuki, KODAMA Yuji, SEIKAI Shigeyuki
    Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 1999(2), 16 Aug. 1999, Japanese
  • An Optical Packet Compressor using a Fiber Loop
    SUZUKI Maoki, NAKADA Fumitoshi, TODA Hiroyuki, KODAMA Yuji, HASEGAWA Akira
    Ultra-high speed optical network systems utilizing optical time-division multiplexing technology require bit-rate converters in order to connect local area networks (LAN) to the high speed inter-LAN network. In this manuscript, we propose a new optical packet compressor using a fiber loop and describe the compression charactoristics. We show operational principle of the packet compression and theoretical estimation of the optical signal-to noise ratio of output packet. Using the fabricated compressor, 25-MHz 50-bit packct, was successfully compressed to 5GHz., Technical report of IEICE. OPE, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OPE, 光エレクトロニクス, 99(39)51 - 55, 13 May 1999, Japanese
  • Influence of noise in optical pulse source on soliton transmission
    Hiroyuki Toda, Katsuyuki Mino, Yuji Kodama, Akira Hasegawa, Peter A. Andrekson
    We performed a 10 Gbit/s optical soliton transmission experiment in a sliding frequency loop and found that the noise in optical source decreased error free distance. The Gordon-Haus timing jitter is theoretically analyzed to verify experimental results., European Conference on Optical Communication, ECOC, 191 - 92, 01 Dec. 1998
  • 10 Gbit/s optical soliton transmission experiment in a comb-like dispersion profiled fiber loop
    Hiroyuki Toda, Yoshihisa Inada, Yuji Kodama, Akira Hasegawa
    We performed 10 Gbit/s optical soliton transmission experiment over 2,000 km with bit error rate of <10-9 in a comb-like dispersion profiled fiber loop of 80 km amplifier spacing which corresponds to nearly the twice of dispersion distance., European Conference on Optical Communication, ECOC, 1101 - 102, 01 Dec. 1998
  • Evaluation of dispersive waves in soliton pulses generated from a Mach-Zehnder modulator and a single mode fiber
    Hiroyuki Toda, Naoki Yamaguchi, Toru Shiozaki, Yuji Kodama, Akira Hasegawa
    We evaluated dispersive wave energy included in a soliton pulse generated from a Mach-Zehnder modulator and a single mode fiber. When pulse repetition is 10 GHz, the minimum dispersive wave energy is only 0.23% when the pulse width is 23 ps, and 3% even when the pulse width is 13 ps., European Conference on Optical Communication, ECOC, 1437 - 438, 01 Dec. 1998
  • Influence of noise in optical pulse source on optical soliton communication
    MINO Katsuyuki, TODA Hiroyuki, KODAMA Yuji, HASEGAWA Akira, ANDREKSON Peter A.
    We performed a 10 Gbit/s optical soliton transmission experiment in a sliding frequency loop and found that the transmission characteristics was influenced by the noise in optical source. The Gordon-Haus timing jitter is theoretically analyzed to verify the experimental results., Technical report of IEICE. OCS, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OCS, 光通信システム, 98(411)37 - 42, 19 Nov. 1998, Japanese
  • 10 Gbit/s optical soliton transmission experiment in a comb-like dispersion profiled fiber
    INADA Yoshihisa, FURUKAWA Yasushi, TODA Hiroyuki, KODAMA Yuji, HASEGAWA Akira
    Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 1998(1), 06 Mar. 1998, Japanese
  • An erbium-doped fiber amplifier with dynamically gain-flattened spectrum
    A. H. Liang, H. Toda, A. Maruta, A. Hasegawa
    Conference on Optical Fiber Communication, Technical Digest Series, 1998-January138 - 139, 01 Jan. 1998
  • Optical soliton transmission in a comb-like dispersion profiled fiber loop
    Hiroyuki Toda, Yasushi Furukawa, Takashi Kinoshita, Yuji Kodama, Akira Hasegawa
    The properties of Type-I and Type-II comb-like dispersion profiled fiber (CDPF) for optical soliton transmission are described. The optical soliton transmission experiment was performed in Type-II CDPF loop. The amplifier spacing of 80 km and the transmission distance of >1,000 km corresponds to 3.1 and >39, respectively in normalized units when pulse width is 10 ps. The Type-II CDPF is more suitable to reduce dispersive waves if transform limited optical pulse is used as a light source. The dispersive wave energy was obtained by subtracting the energy of a soliton which can be obtained by eigenvalue calculation of the Lax pair equation from the total energy of a transmitting pulse., IEE Conference Publication, 319 - 322, 01 Dec. 1997
  • Numerical investigation of dispersive waves in an optical soliton source using a dual-drive Mach-Zehnder modulator
    SHIOZAKI Toru, TODA Hiroyuki, KODAMA Yuji, HASEGAWA Akira
    スライディング周波数や同期振幅変調などのソリトン制御を用いないソリトン伝送系では、光源の光パルスに分散波(非ソリトン成分)が含まれると、誤り率の増加の原因となる。そこで本稿では、Veselkaらが提案した独立駆動マッハーツェンダー変調器を用いたソリトン光源において、出力光パルスに含まれる分散波量を計算し、検討を行ったので報告する。本光源は、電界吸収型(EA)変調器を用いたパルス光源と比べて、駆動回路が若干複雑になるが、低損失で波長依存性が少ないという特長がある。, Proceedings of the Society Conference of IEICE, 一般社団法人電子情報通信学会, 電子情報通信学会ソサイエティ大会講演論文集, 1997(1), 13 Aug. 1997, Japanese
  • 10 ps optical soliton transmission cxperiment in a dispersion managed fiber with amplifier spacing of 80 km
    KINOSHITA Takashi, FURUKAWA Yasushi, TODA Hiroyuki, KODAMA Yuji, HASEGAWA Akira
    光ソリトン通信は, 光ファイバ通信の伝送容景を向上させる技術として注目されている。しかし, エルビウム添加光ファイバ増幅器(EDFA)のような集中増幅器を用いた伝送系では, 増幅器間隔を分散距離よりも十分短くしなければならないという問題がある。増幅器間隔を拡大する方法として, 同期振幅変調器を用いる方法が提案されているが, LN変調器のような能動素子を用いる必要がある。本研究では, このような能動素子を使うことなく増幅器間隔を拡大する方法として, 分散マネジメントについて検討を行った。, Proceedings of the IEICE General Conference, 一般社団法人電子情報通信学会, 電子情報通信学会総合大会講演論文集, 1997(1), 06 Mar. 1997, Japanese
  • Dynamically gain flattened EDFA with bent dispersion shifted fibre
    A. H. Liang, H. Toda, A. Maruta, A. Hasegawa
    A dynamically gain-flattened erbium doped fibre amplifier (EDFA) is demonstrated by inserting a periodically bent dispersion shifted fibre. The gain variation within the 10nm range is < 1dB for a 14dB gain compression. The bending method is simple, cheap, stable, and easily adjustable., Electronics Letters, 332126 - 2127, 01 Jan. 1997
  • 2×10GHz WDM optical soliton loop transmission experiment by utilizing a sliding frequency soliton control
    TODA Hiroyuki, OHTANI Atsushi, HASEGAWA Akira
    波長多重光ソリトン通信では、伝送路中に光フィルタのようなデバイスを挿入してソリトンのパラメータ(振幅、周波数)を適当に制御すれば、波長チャンネル間で光増幅器利得がある程度異なっていても光ソリトンを伝送させることができる。本報告では、2×10GHz波長多重光ソリトン周回伝送実験を行ない、スライディング周波数ソリトン制御によって光増幅器の利得差を吸収できることを確認したので報告する。, Proceedings of the Society Conference of IEICE, 一般社団法人電子情報通信学会, 電子情報通信学会ソサイエティ大会講演論文集, 1996(C)287 , 18 Sep. 1996, Japanese
  • Extension of 10 GHz optical soliton transmission distance in a sliding frequency recirculating fiber loop.
    Uda Tetsuya, Toda Hiroyuki, Hasegawa Akira
    光ソリトン通信の大きな特長は、伝送するソリトンの振幅や速度などのパラメータを制御できることである。この特長を活かせば、例えばソリトン成分をASE雑音のような非ソリトン(分散波)成分と分離して伝送させることができる。我々は前回、このようなソリトン制御のひとつであるスライディング周波数制御を利用した10GHz 4,000km光ソリトン周回伝送実験の結果を報告した。今回、周回実験系に変更を施してGordon-Haus効果による時間ジッタを低減し、伝送距離を拡大したので報告する。, Proceedings of the IEICE General Conference, The Institute of Electronics, Information and Communication Engineers, Proceedings of the IEICE General Conference, 1996(1), 11 Mar. 1996, Japanese
  • Extension of 10GHz optical soliton transmission distance in a sliding frequency recirculating fiber loop
    UDA Tetsuya, TODA Hiroyuki, HASEGAWA Akira
    Extension of 10 GHz optical soliton transmission distance in a sliding frequency recirculating fiber loop is described. We modified the fiber-loop experimental setup as follows. (1)The dispersive wave energy of optical pulses of an MQW electro-absorption modulator was decreased by transmitting through a dispersion compensating fiber. (2) A guiding filter with narrower bandwidth was used for decreasing the Gordon-Haus timing jitter. (3) The propagation loss of the loop was decreased. In a transmission experiment, 10-GHz optical solitons were transmitted over 36,000 km without significant change in pulse width., Technical report of IEICE. OPE, The Institute of Electronics, Information and Communication Engineers, Technical report of IEICE. OPE, 95(459)1 - 6, 18 Jan. 1996, Japanese
  • Reduction of dispersive waves from optical soliton pulses generated with an MQW electro-absorption modulator
    TODA Hiroyuki, MAEDA Yasuhiro, HASEGAWA Akira
    Reduction of dispersive waves from optical soliton pulses generated with an MQW electro-absorption modulator by means of frequency chirp compensation by dispersion compensation fiber (DCF) is described. In eigenvalue calculation, it was found that the dispersive wave energy can be reduced to be l.0 % from 4.6 % when the dispersion-length product was 65.8 ps/nm. In experiment, we observed that the 10-GHz modulator output pulses with the pulse width of 23 ps was compressed to be 17 psec after transmission through DCF of 37.5 ps/nm., Technical report of IEICE. OCS, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. OCS, 光通信システム, 95(272)95 - 53, 28 Sep. 1995, Japanese
  • A study on the detection of optical dark soliton
    SAWADA Ken-ichi, TODA Hiroyuki, HASAGAWA Akira
    ダークリトン(暗いソリトン)は、明るいソリトンに比べて光増幅器雑音をはじめとする線形波や隣接ソリトンとの相互作用の影響が少ないため、より伝送容量が増大できると考えられている。我々は、前回対称駆動マッハーツェンダー変調器によるダークソリトン通信用光源について報告した。今回、この光源を用いたダークソリトン通信の検出方法の比較検討を行ったので報告する。, Proceedings of the Society Conference of IEICE, 一般社団法人電子情報通信学会, 電子情報通信学会ソサイエティ大会講演論文集, 1995(C)275 , 05 Sep. 1995, Japanese
  • Recuction of dispersive waves from optical soliton pulses generated with an MQW EA modulator.
    TODA Hiroyuki, HASEGAWA Akira
    分布帰還型(DFB)半導体レーザと電界吸収型多重量子井戸(MQW)変調器を用いたソリトン光源では、比較的容易に幅10ps程度までの光パルス列を得ることができる。しかしながら、出力光パルス波形がソリトン波形からずれたり、変調器の屈折率変化に起因した周波数チャーピングを含むと、伝送路中において非ソリトン成分である分散波が発生して誤り率増加の原因となる。今回、変調器出力光を分散補償ファイバ(DCF)に伝送させて周波数チャーピングを補償することで、ソリトンパルス中の分散波成分を低減させることを検討した。, Proceedings of the Society Conference of IEICE, The Institute of Electronics, Information and Communication Engineers, Proceedings of the Society Conference of IEICE, 1995(1), 05 Sep. 1995, Japanese
  • Proposal of a light source for optical dark soliton communication with a symmetrically driven Mach-Zehnder modulator.
    SAWADA Ken-ichi, TODA Hiroyuki, HASEGAWA Akira
    ダークソリトン(暗いソリトン)は、明るいソリトンに比べて光増幅器雑音をはじめとする線形波や隣接ソリトンとの相互作用の影響が少ないため、より伝送容量が増大できると考えられている。しかしながら、これまで繰り返しダークソリトン列の発生方法は提案されているものの、情報伝送に必要な変調したダークソリトン発生法は提案されていなかった。今回、新たに対称駆動マッハーツェンダーを変調器によるダークソリトン通信用光源を提案し、基礎実験を行ったので報告する。, Proceedings of the IEICE General Conference, 一般社団法人電子情報通信学会, 電子情報通信学会総合大会講演論文集, 1995(C)241 , 27 Mar. 1995, Japanese
  • 10Gbit/s optical soliton loop transmission experiment by utilizing the effect of sliding filters
    YAMAGISHI Hiroyuki, TODA Hiroyuki, HASEGAWA Akira
    ファイバ中の光ソリトンを用いた長距離通信においては、光増幅器の自然放出雑音に起因して発生する伝送信号のタイミングジッタ(Gordon-Haus効果)によって伝送信号が制限される。この伝送路中に狭帯域光フィルタを挿入するとソリトンの振幅と速度が固定され、Gordon-Haus効果を抑圧することができる。しかし、フィルタの中心周波数での利得が1を越えるため、雑音などの線形波が指数関数的に増大して最終的にソリトンが破壊されるという問題がある。Mollenauerらは、フィルタの中心周波数を伝送距離に応じてゆるやかに変化させる、いわゆるスライディングフィルタを提案した。スライデイングフィルタを挿入した伝送路では、線形波はフィルタによって減衰を受けるが、非線形波であるソリトンは、自らの周波数をフィルタに合わせながら(自己形成)伝搬していく。本研究では、光フィルタの中心周波数を同定し、周回伝送路の光スイッチに音響光学変調器を用いて周回光の周波数をシフトさせることによって、等価的にスライディングフィルタの効果を利用し10Gbit/s光ソリトンの周回伝送実験を行なった。, 電子情報通信学会秋季大会講演論文集, The Institute of Electronics, Information and Communication Engineers, 電子情報通信学会秋季大会講演論文集, 1994(1), 26 Sep. 1994, Japanese
  • 10 Gbit/s optical soliton loop transmission experiment by utilizing the effect of sliding filters
    Toda Hiroyuki, Yamagishi Hiroyuki, Hasegawa Akira
    The optical soliton loop transmission experiment by utilizing the effect of sliding filter is demonstrated.The effect is caused by inserting an acousto-optic modulator(AOM)as an optical frequency shifter and an optical band-pass filter(BPF)in the 20-km long transmission loop.The AOM makes 110 MHz frequency shift in the transmitting lights.The bandwidth of the filter is 1 nm.The optical pulse source which consists of a 1.55 μm DFB laser diode a nd an MQW electro-absorption modulator was used in the experiment. We observed that the soliton frequency was trapped by the optical BPF.Also 10 Gbit, s soliton pulses were transmitted over 4,000 km without any significant change in pulse width., Technical report of IEICE. LQE, 一般社団法人電子情報通信学会, 電子情報通信学会技術研究報告. LQE, レーザ・量子エレクトロニクス, 94(228)94 - 34, 13 Sep. 1994, Japanese
  • Dense-wavelength division multiplexed (DWDM) mm-wave radio-on-fiber systems
    The 5th joint symposium between Doshisha University & Chonnam National University, OE-6, 95 - 98, 2006
  • Error-free multi-channel transmission in 25-GHz spacing DWDM millimeter-wave-band radio-on-fiber system using a supercontinuum light source and arrayed-waveguide-grating filters
    2006 Asia-Pacific Microwave Photonics Conference (AP-MWP 2006), L-2, 355 - 358, 2006
  • Dense WDM broadband radio-on-fiber networks (invited)
    The 11th Optoelectronics and Communications Conference (OECC 2006) Workshop, WS2E, 2006
  • Enabling technology for scalable WDM millimeter-wave-band fiber-radio system (Invited)
    The Australian Telecommunication Networks and Applications Conference 2006 (ATNAC2006), Plenary Session (Wireless Networks), 372 - 375, 2006
  • Future millimeter-wave photonics communication systems (invited)
    Australian Workshop on Microwave Photonics 2006, 2006
  • Future millimeter-wave photonics communication networks (invited)
    2006 Asia-Pacific Microwave Conference (APMC 2006) Workshop, WS11-1, 363 - 369, 2006
  • DWDM millimeter-wave radio-on-fiber systems (invited)
    Asia-Pacific Optical and Wireless Communications (APOC2005), 6021-19, 3a-1,, 2005
  • DWDM millimeter-wave radio-on-fiber systems (invited)
    The 10th International Symposium on Microwave and Optical Technology (ISMOT-2005), C(20), 2005
  • Development of a compact remote base station towards realization of microwave/millimeter-wave dual-band radio-on-fiber transmission (invited)
    The 6th Korea-Japan Joint Workshop on Microwave and Millimter-Wave Photonics (KJJWS6), T2(1), 2005
  • Dense-WDM Millimeter-Wave-Band Radio-on-Fiber System Using a Supercontinuum Light Source:Transmission experiment
    2004
  • A Compact Base Station Prototype Developed for Microwave/Millimeter-Wave Dual-Band ROF System
    2004
  • A consideration on the use of super-continuum light source for millimeter-wave-band radio-on-fiber systems
    2004
  • Dense-WDM Millimeter-Wave-Band Radio-on-Fiber System Using a Supercontinuum Light Source: Transmission experiment
    C14(11), 2004
  • WDM millimeter-wave-band radio-on-fiber system using a supercontinuum light source
    30th European Conference on Optical Communication (ECOC2004), We4P(158), 2004
  • Phase noise characterization of super-continuum light source for WDM mm-wave-band radio-on-fiber systems
    30th European Conference on Optical Communication (ECOC2004), Tu3(5), 2004
  • Polarization-mode dispersion monitoring by the use of self-phase modulation in a fiber
    Topical Meeting of Nonlinear Optics: Materials, Fundamentals and Applications (NLO 2004), ThC5, 2004
  • 40 Gbit/s soliton transmission experiment in a dense dispersion managed fiber with 100 km repeater spacing
    The 9th Optoelectronics and Communications Conference/The 3rd International Conference on Optical Internet (OECC/COIN2004), 14C3, 2004
  • A consideration on nonlinear effect of frequency shifter in photonic downconversion for DWDM ROF systems
    2003
  • Error-free interleaved DWDM transmission of millimeter-wave-band SCM radio-on-fiber signals with photonic downconversion
    2003 Asia-Pacific Microwave Conference (APMC2003) FA6-2, 31526 - 1529, 2003
  • Dense wavelength division multiplexing millimeter-wave-band radio-on-fiber systems (invited)
    The 16th Annual Meeting of the IEEE Lasers and Electro-Optics Society (LEOS2003) ThK3, 2003
  • 740 Gbit/s (37 x 20 Gbit/s) DWDM transmission experiment using Er3+-doped tellurite fiber amplifiers and distributed Raman amplification
    8th OptoElectronics and Communications Conference (OECC2003) 15D3-3, 2569 - 570, 2003
  • DWDM multiplexing with 25-GHz channel spacing using an arrayed wavegudie grating for 60-GHz-band radio-on-fiber systems
    29th European Conference on Optical Communication (ECOC-IOOC2003) Th1.5.2, 4910 - 911, 2003
  • PMD compensation experiment using distributed polarizers Conference on the Optical Internet &Australian Conference on Optical
    Fibre Technology 2003 (COIN/ACOFT 2003) WeB4-3, 2003
  • Photonic downconversion techinique for dense WDM millimeter-wave-band radio-on-fiber signals
    2002
  • Dispersion-effect-free dense WDM millimeter-wave-band radio-on-fiber signal transmission with photonic downconversion
    2002 Asia-Pacific Microuave Conference (APMC2002) 1(WEIC-4), pp.107-110, 2002
  • 25-GHz channel spacing DWDM demultiplexing for 60-GHz band radio-on-fiber systems using on arrayed waveguide grating
    International Topical Meeting on Microwave Photonics (MWP2002), W3(4)33 - 36, 2002
  • 1.5 Tbit/s (75 x 20 Gbit/s) DWDM transmission using Er3+-doped tellurite fiber amplifiers and a single OTDM demultiplexing scheme
    2002
  • Receiver sensitivity of optical RZ receiver using nonlinearity in normal dispersion fiber
    7th OptoElectronics and Communications Conference (OECC2002), 10B1(2)106 - 107, 2002
  • A DWDM mm-wave fiber-radio system by optical frequency interleaving for high spectral efficiency
    International Topical Meeting on Microwave Photonics (MWP2001), Tu3(3)85 - 88, 2002
  • Improvement of Q factor in optical RZ receiver using nonlinearity in normal dispersion fiber Experimental verification in a jitter limited system SubOptic 2001
    2002
  • Improvement of amplitude and phQse margins in optical RZ receiver using nonlinearity in normal dispersion fiber: effect on the Gordon-Haus timing jitter Trans.
    IEEJ, 122A(1)54 - 58, 2002
  • A demultiplexing scheme using an arrayed-waveguide grating for a DWDM mm-wave fiber-radio system by optical frequency interleaving
    8th Microoptics Conference (MOC'01), C240 - 43, 2001
  • DWDM millimeter-wave radio-on-fiber systems (invited)
    Asia-Pacific Optical and Wireless Communications (APOC2005), 6021(19)

Works

  • Research on nonlinear optics and ultra-fast optical fiber transmission based on theory of integrable systems
    1996 -1999
  • Theoretical and experimental research on soliton transmission and generation
    1998
  • Pico-second optical solitons, generation and application to ultra fast communication
    1995 -1996
  • Optical soliton communication -Application to the long distance and high data-bit communication-
    1995 -1996
  • Research on behavior of optical soliton and their application to ultra long distance, ultra high speed communications
    1992 -1995
  • Research on ultra-fast and large-capacity optical soliton transmission
    1995
  • Theoretical investigation for multiplexing of optical soliton communications
    1992 -1994
  • Experimental research on application of optical solitons to long-distance and large-capacity communication
    1993

Patents

  • Performance of fiber transmission systems by transforming return-to-zero format to non-return-to-zero format in front of receiver
    US2003011839-A1
  • Optical fiber mesuring module
    WO2004/048889, AU2002349723(A1)
  • Optical fiber measuring module
    AU2002349723(A1)
  • Optical fiber measuring module
    US2006001863(A1)

Research Grants & Projects

  • Wavelength-division multiplexed radio on fiber
    2000
  • Research on ultra-fast fiber-optic transmission and optical signal processing using optical nonlinearity
    Grant-in-Aid for Scientific Research, 1992

Research cooperation among industry, academia and government

  • Joint Research Theme:Optical fiber communication
    Remarks:Cooperative research with other research organization including private (industrial) sectors

Research Seeds

  • Optical communication, Interferometer, Optical experiments
    Affiliation/Name: Hiroyuki Toda
    Patent Information: 特願 2006-242705