今宿 亙 (イマジュク ワタル)

  • 産業理工学部 電気電子工学科 教授
Last Updated :2024/04/23

コミュニケーション情報 byコメンテータガイド

  • コメント

    将来のBeyond 5Gモバイル通信システム用の光伝送インフラ技術の研究や量子暗号通信用超低雑音光増幅技術の研究を行っています。 最近は、ナショナルプロジェクトに参加し、グローバル企業各社と共同研究を行っています。

研究者情報

学位

  • 博士(工学)(2002年12月 東京大学)

ホームページURL

科研費研究者番号

  • 00530817

ORCID ID

J-Global ID

研究キーワード

  • ネットワーク   光通信   通信工学   

現在の研究分野(キーワード)

    将来のBeyond 5Gモバイル通信システム用の光伝送インフラ技術の研究や量子暗号通信用超低雑音光増幅技術の研究を行っています。
    最近は、ナショナルプロジェクトに参加し、グローバル企業各社と共同研究を行っています。

研究分野

  • 情報通信 / 情報ネットワーク / インターネット工学
  • ものづくり技術(機械・電気電子・化学工学) / 通信工学 / 光通信工学

経歴

  • - 現在  近畿大学産業理工学部 電気電子工学科/実学社会起業イノベーション学位プログラム教授/学術情報センター長
  • 2011年07月  Verio Inc. (現 NTT America)副社長
  • 2002年12月  博士(工学) (東京大学)
  • 1994年04月  日本電信電話(株)担当部長・主幹研究員, 担当課長・主任研究員, 研究員

所属学協会

  • 電子情報通信学会   IEEE   

研究活動情報

論文

  • W. Imajuku; D. Aoki; Y. Yamaga; K. Yamamoto; S. Takahashi
    IEEE/OSA Journal of Lightwave Technology 42 6 1853 - 1860 2024年03月 [査読有り]
     
    Index modulation has received a lot of interest in the wireless communication field in the last decade, since this technology can enhance the data transmission rate per energy (Eb/N0) in low signal power conditions. This gain originates from the utilization of index activation patterns that can transmit part of the data without consuming additional energy. This inherent characteristic of index modulation can be used to develop a new elastic optical fiber access service that supports energy efficient intermediate data rates in ultra-low signal power conditions. We evaluate the receiver sensitivity of a Time-Domain Single Carrier (8,1,BPSK) Index Modulation optical signal with symbol rate of 2.5 GBaud for the first time. We confirm 3 dB gain in Eb/N0 values and 6 dB margin to maintain optical link connectivity compared to BPSK optical signaling.
  • W. Imajuku; S. Takahashi; Y. Nakamura; R. Akahoshi
    IEICE Communications Express 13 3 68 - 71 2024年03月 [査読有り]
     
    This paper studies non-integer power of two-ary quadrature amplitude modulation (QAM) for long-haul optical fiber transmission systems. Numerical simulations show that 12-QAM and 24-QAM provide intermediate solutions on reachable transmission distances among traditional M-QAM such as C8-QAM, 16-QAM, and 32-QAM. In addition, short block length probabilistic shaping of 24-QAM not only provides an intermediate solution with nonlinear tolerance, but also yields greater transmission distances than 16-QAM for the same information data rates.
  • T. Tanaka; T. Inui; A. Kadohata; A. Hirano; W. Imajuku
    IEEE/OSA Journal of Optical Communications and Networking 8 7 A180 - A190 2016年07月 [査読有り]
  • A. KADOHATA; T. TANAKA; F. INUZUKA; A. WATANABE; W. IMAJUKU
    IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences E99.A 8 1510 - 1517 2016年 [査読有り]
  • W. Shen; M. Yoshida; K. Minato; W. Imajuku
    IEEE Communications Magazine 53 2 116 - 124 2015年02月 [査読有り]
  • Y. SONE; A. Watanabe; W. Imajuku; Y. Tsukishima; B. Kozicki; H. Takara; M. Jinno
    IEEE/OSA Journal of Optical Communications and Networking 3 3 223 - 233 2011年03月 [査読有り]
  • W. Imajuku; E. Oki; R. Papneja; S. Morishita; K. Ogaki; M. Miyazawa; K. Miyazaki; H. Nakazato; H. Sugiyama; John Allen; S. Hasegawa; N. Sakuraba; I. Nishioka; S. Seno; Y. Nakahira; D. Ishii; S. Okamoto; Tara Van Unen; Mark Blumhardt; Hari Rakotoranto; Vijay Pandian
    IEEE Communications Magazine 47 2 168 - 175 2009年 [査読有り]
     
    This article describes the first multi-area multiprotocol label switching and generalized MPLS interoperability trial over a reconfigurable optical add/drop multiplexer and optical cross-connect network. The interoperability trial demonstrated the routing of label switched paths over a multi-area GMPLS controlled ROADM/OXC network and the control of Ethernet over MPLS transport service on top of the GMPLS network. The trial was conducted using various network elements provided by 14 institutions and was carried out in Tokyo and Virginia. This article introduces the motivation for the trial, technical issues related to controlling multiarea MPLS/GMPLS networks, test network topology, and experimental results. The results show that the interior gateway routing protocolbased multi-area routing architecture is a promising solution for the nationwide deployment of GMPLS networks within a carrier domain. In addition, this article discusses the technical issues of routing constraints in ROADM/OXC networks and the limit of multiarea routing without the Path Computation Element Protocol. © 2009 IEEE.
  • Y. SONE; W. IMAJUKU; N. NAGATSU; M. JINNO
    IEICE Transactions on Communications E92-B 1 46 - 58 2009年 [査読有り]
  • A. Taniguchi; Y. Sameshima; S. Okamoto; T. Otani; Y. Okano; Y. Tsukishima; W. Imajuku
    IEEE Communications Magazine 46 5 60 - 66 2008年05月 [査読有り]
  • S. Yamamoto; I. Shake; T. Kurahashi; Y. Tarui; W. Imajuku; Y. Tsukishima; K. Sasayama; O. Moriwaki; M. Fukutoku
    IEEE/OSA Journal of Lightwave Technology 25 9 2864 - 2873 2007年09月 [査読有り]
  • W. Imajuku; T. Ohara; Y. Sone; I. Shake; Y. Sameshima; M. Jinno
    IEICE Transactions on Communications E90B 8 1952 - 1959 2007年08月 [査読有り]
     
    The objective of this paper is to survey the Generalized Multi-Protocol Label Switching (GMPLS) based recovery technology for optical transport networks. This paper introduces standardization activities of the GMPLS based recovery technology in the Internet Engineering Task Force (IETF), and recent progress of related experiments. In addition, this paper extracts requirements for the GMPLS based recovery technology through the evaluation of existing network elements, which can be client nodes of the optical transport networks. The results of field evaluations on the GMPLS based recovery technology are also introduced in this paper. Then, this paper addresses the issues for future deployment of the GMPLS based recovery technology for the optical transport networks.
  • P. Szegedi; T. Gajewski; W. Imajuku; S. Okamoto
    IEICE Transactions on Communications E90B 8 1944 - 1951 2007年08月 [査読有り]
     
    In this paper the current trends in the optical networking including the physical components, technologies and control architectures are discussed. The possible interaction schemes and implementation models of the automatic communication between applications and network as well as between ASON/GMPLS based network domains are proposed. Finally, the related research activities based on simulation results of control plane dimensioning are illustrated and real test bed experiments on OIF worldwide interoperability demonstration and the ongoing European IST project MUPBED are disseminated.
  • S. Okamoto; W. Imajuku; T. Otani; I. Nishioka; A. Nagata; M. Nanba; H. Otsuki; M. Suzuki; N. Yamanaka
    IEICE Transactions on Communications E90B 8 1936 - 1943 2007年08月 [査読有り]
     
    Generalized Multi-protocol Label Switching (GMPLS) technologies are expected a key technology that creates high-performance Internet backbone networks. There were many GMPLS interoperability trials. However, most of them reported the successful results only. How to set up a trial network and how to test it was generally not discussed. In this paper, as a kind of tutorial, detailed GMPLS field trials in the National Institute of Information and Communications Technology (NICT) Kei-han-na Info-Communication Open Laboratory, Interoperability Working Group (WG) are reported. The interoperability WG is aiming at the leading edge GMPLS protocol based Inter-Carrier Interface that utilizes wide-bandwidth, cost-effective photonic technology to implement IP-centric managed networks. The interoperability WG is a consortium for researching the GMPLS protocol and advancing a de facto standard in this area. Its experimental results, new ideas, and protocols are submitted to standardization bodies such as the International Telecommunications Union-Telecommunication standardization sector (ITU-T), the Internet Engineering Task Force (IETF), and the Optical Internetworking Forum (OIF). This paper introduces the activities of the interoperability WG; they include a nationwide GMPLS field trial using the JGN II network with multi-vendor, multi-switching-capable equipment and a GMPLS multi routing area trial that used a multi-vendor lambda-switching-capable network.
  • OTSUKA Y; KIMURA T; YAGINUMA H; WATANABE A; IMAJUKU W
    IEICE Transactions on Communications J89B 11 2103 - 2116 一般社団法人電子情報通信学会 2006年11月 [査読有り]
     
    近年のIP系ブロードバンドサービスの拡大によるトラヒックの増大に伴い,波長多重技術,光スイッチング技術,自律制御プロトコル技術を用いた光ネットワークが注目されている.しかし,複数の装置及び複数のレイヤで構成されたネットワークを統合的に管理し,効率的なネットワーク運用をサポートするマルチレイヤネットワーク管理技術についての検討は十分とはいえない.本論文ではGMPLS制御機構を有する光クロスコネクト装置及びコアルータ装置で構成されたMPLS/SDH/OTNマルチレイヤネットワークを対象として,統合管理に向けた課題を明確化するとともに,マルチレイヤパスの管理モデル,パス制御管理方式,故障管理方式,及びSRLGの概念に基づくリスク,コスト優先制御管理方式について提案する.更に,試作による機能確認,GMPLSによる開通方式とネットワーク管理システムによる開通方式との比較評価についても述べる.
  • A. Takefusa; M. Hayashi; N. Nagatsu; H. Nakada; T. Kudoh; T. Miyamoto; T. Otani; H. Tanaka; M. Suzuki; Y. S; W. Imajuku; M. Jinno; Y. Takigawa; S. Okamoto; Y. Tanaka; S. Sekiguchi
    FUTURE GENERATION COMPUTER SYSTEMS 22 8 868 - 875 2006年10月 [査読有り]
     
    At iGrid2005, we conducted a live demonstration where our Grid scheduling system co-allocated computing and network resources with advance reservation through Web services interfaces using the Grid Resource Scheduler (GRS), the Network Resource Management System (NRM), which is capable of GMPLS network resource management, and a GMPLS-based network test-bed, for the first time. The goal of the G-lambda project is to define a standard Web services interface (GNS-WSI) between GRS and NRM that is acceptable for both application service providers and commercial network operators, and which can be used as a tool for realizing new and emerging commercial services. (c) 2006 Elsevier B.V. All rights reserved.
  • OPTICAL PATH RESTORATION SCHEME ESCALATION ACHIEVING ENHANCED OPERATION AND HIGH SURVIVABILITY IN MULTIPLE FAILURE SCENARIOS
    Y. Sone; N. Nagatsu; W. Imajuku; M. Jinno; Y. Takigawa
    Transaction of WTC NW1 2-1 - 8 2006年05月 [査読有り]
  • W. Imajuku; Y. Sone; N. Nagatsu; A. Sahara; Y. Takigawa
    IEICE Transactions on Communications E88-B 10 3914 - 3921 2005年10月 [査読有り]
  • J Yamawaku; A Takada; W Imajuku; T Morioka
    IEEE/OSA Journal of Lightwave Technology 23 6 1971 - 1978 2005年06月 [査読有り]
     
    In this paper, the authors propose novel nongrooming, optical path cross-connect (OXC), single-layer optical path (OP) networks that can route multigranularity optical paths with reduced optical switch (OSW) size. Since the multigranularity OP's are handled in one OP layer, the configuration and path administration of the OXCs become simple. The authors evaluate the network topology dependency of the network elements, i.e., the required number of OSW ports and fibers in networks consisting of 36 fixed nodes with different network topologies as well as that of a 16-OXC, 25-link NSFNET. The proposed networks require 60% fewer OSW ports, enabling efficient link resource utilization. A 60% reduction in total network cost is also confirmed.
  • E Oki; K Shiomoto; D Shimazaki; N Yamanaka; W Imajuku; Y Takigawa
    IEEE Communications Magazine 43 1 108 - 114 2005年01月 [査読有り]
     
    This article presents two dynamic multilayer routing policies implemented in the photonic MPLS router developed by NTT for IP+optical generalized MPLS networks. According to IP traffic requests, wavelength paths called lambda label switched paths are set up and released in a distributed manner based on GMPLS routing and signaling protocols. Both dynamic routing policies first try to allocate a newly requested electrical path to an existing optical path that directly connects the source and destination nodes. If such a path is not available, the two policies employ different procedures. Policy 1 tries to find available existing optical paths with two or more hops that connect the source and destination nodes. Policy 2 tries to establish a new one-hop optical path between source and destination nodes. The performances of the two routing policies are evaluated. Simulation results suggest that policy 2 outperforms policy 1 if p is large, where p is the number of packet-switching-capable ports; the reverse is true only if p is small. We observe that p is the key factor in choosing the most appropriate routing policy. We also describe items that need to be standardized in the IETF to effectively achieve multilayer traffic engineering.
  • E Oki; K Shiomoto; M Katayama; W Imajuku; N Yamanaka; Y Takigawa
    IEICE Transactions on Communications E87B 6 1577 - 1583 2004年06月 [査読有り]
     
    This paper presents two dynamic multi-layer routing policies for optical IP Networks. Both policies first try to allocate a newly requested electrical path to an existing optical path that directly connects the source and destination nodes. If such a path is not available, the two policies employ different procedures. Policy 1, which has been published already, tries to find available existing optical paths with two or more hops that connect the source and destination nodes. Policy 2, which is proposed in this paper, tries to establish a new one-hop optical path between source and destination nodes. The performances of the two routing policies are evaluated. Simulation results suggest that policy 2 outperforms policy I if p is large, where p is the number of packet-switching-capable ports; the reverse is true only if p is small. We observe that p is the key factor in choosing the most appropriate routing policy.
  • K Shiomoto; E Oki; W Imajuku; S Okamoto; N Yamanaka
    IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 21 8 1254 - 1262 2003年10月 [査読有り]
     
    This paper proposes a distributed virtual network topology (VNT) reconfiguration method for Internet protocol over wavelength-division-multiplexing network under dynamic traffic demand. We developed a simple heuristic algorithm for calculating the VNT for distributed control. Generalized multiprotocol, label switching (GMPLS)-based routing protocol has been developed. The VNT is quickly reconfigured by setting up and/or tearing down lightpaths using GMPLS signaling protocol. Traffic demand is measured at the ingress node and advertised by the extended GMPLS routing protocol. Performance of the proposed method is investigated using variable traffic model.
  • W Imajuku; A Takada
    IEEE JOURNAL OF QUANTUM ELECTRONICS 39 6 799 - 812 2003年06月 [査読有り]
     
    The noise figure (NF) of a phase-sensitive parametric amplifier using a nonlinear Mach-Zehnder interferometer (NMZI) with Kerr media is analyzed for amplitude-modulation signals. In the analysis, the distributed loss of the Kerr media and the excess noise of the pump light are taken into account. As for the distributed loss of the Kerr media, the quantum Langevin equation for the NMZI is derived and solved. The results elucidate a simple degradation factor in the NF representation of the amplifier. This factor implies that the NF can be less than the standard quantum limit (SQL) of 3 dB, even if the total loss of the Kerr media exceeds 3 dB. As for the excess noise of the pump light, the semi-classical small signal analysis is utilized. The results clearly indicate that the signal-to-noise ratio of the pump light must be four times higher than that of the input signal in order to realize a low-noise optical amplifier under the SQL of 3 dB.
  • Dynamic Multi-Layer Traffic Engineering in GMPLS Networks
    K. Shiomoto; E. Oki; M. Katayama; W. Imajuku; N. Yamanaka
    Transaction of WTC TS07 1-1 - 6 2002年09月 [査読有り]
  • Adaptive transparent photonic network control techniques based on photonic-GMPLS-router network
    N. Yamanaka; S. Okamoto; K. Shomoto; E. Oki; W. Imajuku
    Transaction of WTC TS07 3-1 - 6 2002年09月 [査読有り]
  • K Sato; N Yamanaka; Y Takigawa; M Koga; S Okamoto; K Shiomoto; E Oki; W Imajuku
    IEEE Communications Magazine 40 3 96 - 101 2002年03月 [査読有り]
     
    A new extended signaling and traffic engineering method for the GMPLS-based photonic and electrical multilayer router (Hikari router) is proposed. The method allows dynamic optical network management and photonic signal recovery, such as regeneration, reshaping, etc., to be realized adaptively. Wavelength conversion is also adaptive, which reduces network cost. Multilayer traffic engineering, which yields the dynamic cooperation of IP and photonic layers, is described to provide IP services cost effectively. To realize multilayer traffic engineering, we propose the OSPF extension, which advertises both the number of total wavelengths and the number of unused wavelengths, and the RSVPTE extension, which minimizes the number of wavelength conversions needed. In addition, this paper proposes a heuristics-based multilayer topology design scheme that uses IP traffic measurements in a generalized multi-protocol label switch (GMPLS). The proposed scheme yields the optical label switch path (OLSP) network topology, that is, OLSP placement, that minimizes network cost, in response to fluctuations in IP traffic demand. In other words, the OLSP network topology is dynamically reconfigured to match IP traffic demand. Networks are reconfigured by the proposed scheme so as to utilize network resources in the most cost effective manner.
  • A. TAKADA; W. IMAJUKU
    The Review of Laser Engineering 29 9 599 - 604 The Laser Society of Japan 2001年09月 [査読有り][招待有り]
     
    Coherent optical amplifiers intensify the amplitude of the component which has a given optical phase and attenuate the amplitude of the component which has the optical phase orthogonal to the 'amplified phase'. Principles, effectiveness in the optical transmission and current status of experimental demonstrations of the coherent amplifiers are reviewed.
  • 今宿, 高田
    応用物理 69 11 1320 - 1324 The Japan Society of Applied Physics 2000年 [査読有り][招待有り]
     
    コヒーレント光増幅器は,コヒーレント光検波技術と光パラメトリック増幅技術を併用することで,光位相に依存したパワー利得を実現する線形光増幅器である.この特徴的な動作により,既存のレーザー光増幅器,ラマン光増幅器などの限界とされる標準量子限界(雑音指数3dB)以下の低雑音光増幅が原理的に可能とされる.また,光周波数チャーピングにより波形がひずんだ超短パルスの波形整形動作も実現可能である.本稿では,このコヒーレント光増幅器の原理と,最近の研究動向について紹介する.
  • W Imajuku; A Takada; Y Yamabayashi
    ELECTRONICS LETTERS 36 1 63 - 64 2000年01月 [査読有り]
     
    The first demonstration of an inline coherent optical amplifier with a noise figure which is lower than the 3dB quantum limit is presented. The amplifier is based on optical phase-sensitive amplification using a nonlinear fibre Sagnac interferometer pumped by an injection-locked semiconductor laser with a compensation phase-locked loop. A noise figure of 2.0dB with a high signal gain of 16dB has been successfully obtained.
  • W. Imajuku; A. Takada
    IEEE Journal of Quantum Electronics 35 11 1657 - 1665 1999年11月 [査読有り]
     
    This paper investigates the gain characteristics of coherent optical amplifiers that amplify only one of two quadrature phase components in an input signal light according to the phase of pump light. It is constructed around a Mach-Zehnder interferometer with Kerr media. To heuristically obtain the design parameters of the coherent optical amplifier, small-signal analysis is adapted to the Mach-Zehnder interferometer with Kerr media. The theoretical results are then compared to experimental results and shown to agree well, which confirms the validity of this design approach. By utilizing low-loss and high-nonlinearity silica fiber as the Kerr medium and optimizing its length, a coherent optical amplifier is constructed that yields high-gain (up to 26 dB) operation.
  • W Imajuku; A Takada; Y Yamabayashi
    ELECTRONICS LETTERS 35 22 1954 - 1955 1999年10月 [査読有り]
     
    A noise figure which is less than the standard quantum limit of 3dB has been observed for the first time in a high gain phase-sensitive fibre parametric amplifier. A noise figure of 1.8dB with a 16dB signal gain was measured by a precisely calibrated electrical spectrum analyser.
  • W Imajuku; A Takada
    IEEE/OSA Journal of Lightwave Technology 17 4 637 - 646 1999年04月 [査読有り]
     
    This paper describes an in-line optical phase-sensitive amplifier (PSA) with a pump laser whose optical phase is locked to that of a randomly modulated signal by using an optical phase-lock loop (OPLL). The OPLL is designed with the capability of optical phase locking at an arbitrary relative phase. Experimental evaluation is presented of the OPLL employing a newly developed external cavity semiconductor ring laser with a spectrum linewidth df less than 20 kHz. Employing this pump laser with the OPLL in conjunction with a 4.4-km long nonlinear fiber Sagnac interferometer (NFSI) yields optical phase-sensitive gain of up to 11 dB, A randomly modulated signal is successfully amplified and confirmed offering a clear eye-opening.
  • W Imajuku; A Takada
    ELECTRONICS LETTERS 34 17 1673 - 1674 1998年08月 [査読有り]
     
    Optical phase-sensitive amplifiers (PSAs) are promising circuit elements for expanding the regenerative repeater spacing of optical transmission systems. The authors first demonstrate error-free operation of in-line PSAs with a 10dB net gain by using an injection-locked pump with a compensation phase-locked loop.
  • W Imajuku; A Takada
    IEEE/OSA Journal of Lightwave Technology 16 7 1158 - 1170 1998年07月 [査読有り]
     
    This paper shows the theoretically derived performance of single channel, amplitude modulation/direct detection optical transmission systems using in-line optical phase-sensitive amplifiers (PSA's), The calculations take into account the degradation of the signal-to-noise power ratio (SNR) and intersymbol interference (ISI) due to the distortion of transmitted signal pulses. The SNR is analyzed by considering not only amplifier noise and fiber loss but also noise enhancement by four-wave mixing in the transmission fiber. The ISI is estimated by eye-pattern degradation of the transmitted signal numerically calculated using the nonlinear Schrodinger equation. The regenerative repeater spacing of in-line PSA systems limited by SNR and ISI can be expanded by approximately 3 to 10 times that of in-line EDFA systems, in the case of \D\ less than or equal to 0.1 ps/nm/km dispersion fiber systems transmitting a 40-Gb/s signal.
  • A Takada; W Imajuku
    ELECTRONICS LETTERS 34 3 274 - 276 1998年02月 [査読有り]
     
    An in-line optical phase-sensitive amplifier with a phase-locked pump source is demonstrated. The pump source, which consists of a modelocked semiconductor ring laser, is phase-locked to the input signal light by optical injection of the signal. The randomly modulated signal pulses are successfully amplified in a Sagnac interferometer-type parametric amplifier pumped by the injection-locked laser.
  • W Imajuku; A Takada
    ELECTRONICS LETTERS 33 25 2155 - 2156 1997年12月 [査読有り]
     
    Randomly modulated signal pulses from an independent source are successfully amplified by a phase-sensitive amplifier with an internal pump light whose optical phase is locked to that of the injected signal using an optical phase-locked loop.
  • A Takada; W Imajuku
    IEEE PHOTONICS TECHNOLOGY LETTERS 9 10 1328 - 1330 1997年10月 [査読有り]
     
    The linewidth of the individual modes of an actively mode-locked extended-ring-cavity semiconductor laser is reduced from a free running linewidth of over 200-20 kHz by the injection of a narrow linewidth continuous-wave (CW) tight. The optical phase of the injection-locked pulses can be controlled by adjusting the free-running optical frequency of the semiconductor ring laser. The variation in the optical phase of the output pulses versus the change of the free-running optical frequency is evaluated to be 0.57 pi radians within the locking range of about 96 MHz by observing temporal shape of the beat signal formed between output pulses and CW injection light.
  • W Imajuku; A Takada
    ELECTRONICS LETTERS 33 16 1403 - 1404 1997年07月 [査読有り]
     
    Optical phase-sensitive amplification using individual pump and signal light sources is presented for the first time. In the experiment, optical phase of pump and signal light is locked by an optical phase-locked loop (OPLL). Stable optical phase-locking is achieved and optical phase-sensitive amplification with a gain of 12dB is successfully demonstrated using a nonlinear Sagnac interferometer.
  • W Imajuku; A Takada
    OSA OPTICS LETTERS 22 1 31 - 33 1997年01月 [査読有り]
     
    In optical fiber transmission systems near the zero-dispersion wavelength that use in-line erbium-doped fiber amplifiers (EDFA's), the enhancement of optical amplifier noise caused by four-wave mixing (FWM) in transmission fibers degrades signal-to-noise ratio (SNR) excessively. We theoretically show that the enhancement of amplifier noise by the FWM in transmission fibers can be effectively eliminated by implementing in-line phase-sensitive amplifiers (PSA's). Small-signal analysis of the nonlinear Schrodinger equation shows that the transmission distance limited by the SNR of an in-line PSA system is expanded four times more than that of an in-line EDFA system. (C) 1997 Optical Society of America
  • A Takada; W Imajuku
    ELECTRONICS LETTERS 32 7 677 - 679 1996年03月 [査読有り]
     
    A phase sensitive gain of 23dB is achieved using a pulse excited nonlinear loop mirror with a 3km zero dispersion optical fibre. It is shown that the phase sensitive amplifier (PSA) behaves as a limiting amplifier in the high input signal power region. The suppression of amplitude fluctuation in the input signal is also demonstrated using the PSA as a limiting amplifier.
  • W IMAJUKU; M TAKAHASHI; M KOBAYASHI
    Japanese Journal of Applied Physics 34 4A 1861 - 1866 1995年04月 [査読有り]
     
    Theoretical design of ZnSSe/ZnCdSSe laser diodes emitting 460 nm at room temperature (RT) was studied by means of threshold current analysis. The threshold current density calculation was based on the laser theory established for the III-V laser diode (LD) system. The result of the threshold current density calculation indicated that the reduction of carrier overflow is an essential issue in realizing the device with a reasonable threshold current level at RT. Another indication is that 30% S content in the ZnSSe cladding layer would be a suitable target value for a practical 460 nm LD at RT, along with a multiple quantum barrier structure. The predicted threshold current density of such a LD could be as low as 450 A/cm(2) at RT.

書籍

  • IETF RFC 7579: General Network Element Constraint Encoding for GMPLS-Controlled Networks
    G. Bernstein; Y. Lee; D. Li; W. Imajuku; J. Han (担当:共著範囲:)InternetEngineering Task Force 2015年06月
  • IETF RFC 7581: Routing and Wavelength Assignment Information Encoding for Wavelength Switched Optical Networks
    G. Bernstein; Y. Lee; D. Li; W. Imajuku; J. Han (担当:共著範囲:IETF RFC 7581: Routing and Wavelength Assignment Information Encoding for Wavelength Switched Optical Networks)InternetEngineering Task Force 2015年06月
  • IETF RFC 7446: Routing and Wavelength Assignment Information Model for Wavelength Switched Optical Networks
    Y. Lee; G. Bernstein; D. Li; W. Imajuku (担当:共著範囲:)InternetEngineering Task Force 2015年02月
  • IETF RFC 6163: Framework for GMPLS and Path Computation Element (PCE) Control of Wavelength Switched Optical Networks (WSONs)
    Y. Lee; G. Bernstein; W. Imajuku (担当:共著範囲:)InternetEngineering Task Force 2011年04月
  • 1997 Tops Optical Amplifiers and Their Applications (OSA Trends in Optics and Photonics)
    W. Imajuku; A. Takada (担当:分担執筆範囲:)1997年07月 ISBN: 1557525056

講演・口頭発表等

MISC

産業財産権

受賞

  • 2015年06月 日本電信電話(株) 特許実施補償表彰 特級
  • 2014年09月 APNOMS 2014 Best Paper Award
  • 2009年03月 日本電信電話(株) 平成20年度 未来ねっと研究所所長表彰
     SINET 3における共同研究支援
  • 2008年07月 OECC/IOOC 2007 Best Paper Award
  • 2007年02月 日本電信電話(株) 平成18年度 先端総合技術総合研究所所長表彰
     GMPLS制御によるリストレーションならびにL1-VPN実現技術に関する基本特許
  • 2006年03月 日本電信電話(株) 平成17年度 未来ねっと研究所所長表彰
     フォトニックIXアーキテクチャの提案と基本動作の実証
  • 2003年12月 日本電信電話(株) 平成15年度 先端総合技術研究所所長表彰
     GMPLS/GSMP光クロスコネクト制御基盤技術の研究開発
  • 2003年09月 HPSR 2003 Best Paper Award
  • 2000年03月 日本電信電話(株) 平成11年度 未来ねっと研究所所長表彰
     超低雑音コヒーレント光増幅の実証
  • 2000年03月 電子情報通信学会 平成11年度 学術奨励賞
  • 1997年01月 日本電信電話(株) 平成8年度 光ネットワークシステム研究所所長表彰
     位相感応光増幅器の研究

共同研究・競争的資金等の研究課題

  • 広域分布型地震計測システムの研究開発
    福岡県飯塚市:研究助成
    研究期間 : 2022年07月 -2023年03月
  • 非線形位相雑音耐力のある光伝送路符号化方式の研究 (H31-R2)
    一般財団法人 テレコム先端技術研究支援センター:研究助成
    研究期間 : 2019年04月 -2021年03月 
    代表者 : 今宿
  • 非線形伝送符号化を用いた光伝送方式の研究 (H30-R1)
    公益財団法人 電気通信普及財団:研究調査助成
    研究期間 : 2018年04月 -2020年03月 
    代表者 : 今宿
  • 地盤・建造物の温度・歪同時計測を可能とする 低コスト光ファイバセンサの研究開発 (H29-R1)
    福岡県飯塚市:研究助成
    研究期間 : 2017年08月 -2020年03月 
    代表者 : 今宿
  • 利得飽和型パラメトリック増幅器と非線形伝送路符号を適用した次世代光伝送方式の研究 (H29-R1)
    日本学術振興会:科学研究費助成事業 基盤研究(C)
    研究期間 : 2017年04月 -2020年03月 
    代表者 : 今宿
  • 光中継ノードにおける波長変換光回路の研究 (H30)
    民間企業:受託研究
    研究期間 : 2018年06月 -2019年03月 
    代表者 : 今宿
  • 光中継ノードにおける非線形位相ノイズ補償技術の研究 (H28-H29)
    民間企業:受託研究
    研究期間 : 2016年08月 -2018年03月 
    代表者 : 今宿
  • エラスティック光通信ネットワーク構成技術の研究開発(H26-H27)
    情報通信機構:高度通信・放送研究開発委託研究
    研究期間 : 2015年04月 -2016年03月
  • 光ネットワークのキャリア間インタフェイスの標準化(H18-H20)
    総務省:戦略的情報通信研究開発推進制度(SCOPE: Strategic Information and Communications R&D Promotion Program) 国際技術獲得型研究開発
    研究期間 : 2006年04月 -2009年03月

委員歴

  • 2018年06月 - 現在   超高速フォトニックネットワーク開発推進協議会   企画部会長代理
  • 2016年04月 - 現在   超高速フォトニックネットワーク開発推進協議会   技術調査委員
  • 2006年04月 - 現在   電子情報通信学会   論文査読委員
  • 2019年01月 - 2022年03月   総務省   研究プロジェクト 運営委員
  • 2017年03月 - 2017年06月   ipop2017   Technical Program Comittee
  • 2016年03月 - 2016年07月   OECC2016   Work Shop Organizer
  • 2016年02月 - 2016年06月   Photonic Internet Laboratory ipop2016   Technical Program Committee Chair
  • 2012年02月 - 2012年06月   Photonic Internet Laboratory ipop2012   Technical Program Committee
  • 2011年02月 - 2011年06月   Photonic Internet Laboratory ipop2011   Technical Program Committee
  • 2010年04月 - 2010年06月   Photonic Internet Laboratory ipop2010   Exhibition vice chair
  • 2006年04月 - 2009年03月   電子情報通信学会   PN研究会専門委員
  • 2008年04月 - 2008年06月   2008 Conference on Optical Internet   Technical Program Committee
  • 2008年04月 - 2008年06月   Photonics in switching 2008   Technical Program Committee
  • 2008年02月 - 2008年06月   Photonic Internet Laboratory ipop2008   Technical Program Committee
  • 2006年01月 - 2006年04月   IEEE Infocom 2006   Technical Program Committee
  • 2004年06月 - 2004年11月   米国工学アカデミー・EAJ・JST主催日米先端工学シンポジウム(JAFoE)   推進委員
  • 1999年04月 - 2001年03月   日本光学会   光科学及び光技術調査委員会 委員

その他のリンク

researchmap



Copyright © MEDIA FUSION Co.,Ltd. All rights reserved.