Koike, Yasuhiro

写真a

Affiliation

University （Mita）

Position

Professor (Non-tenured)
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Other Affiliation 【 Display / hide 】

  • Keio Photonics Research Institute, Director

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Career 【 Display / hide 】

  • 1982.04
    -
    1983.03

    Keio University, Faculty of Science and Technology, 非常勤講師

  • 1983.04
    -
    1988.03

    Keio University, Faculty of Science and Technology,  助手

  • 1988.04
    -
    1992.03

    Keio University, Faculty of Science and Technology, 専任講師

  • 1989.04
    -
    1990.02

    AT&T Bell Laboratories, Visiting Researcher

  • 1992.04
    -
    1997.03

    Keio University, Faculty of Science and Technology,  助教授

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Academic Background 【 Display / hide 】

  • 1977.03

    Keio University, Faculty of Engineering, Department of Applied Chemistry

    University, Graduated

  • 1979.03

    Keio University, Graduate School, Division of Engineering

    Graduate School, Completed, Master's course

  • 1982.03

    Keio University, Graduate School, Division of Engineering

    Graduate School, Completed, Doctoral course

  • 2007.04

    Eindhoven University of Technology, Electrical Engineering

    Netherlands, Graduate School, Other, Doctoral course

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Academic Degrees 【 Display / hide 】

  • Engineering, Keio University, 1982.03

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Research Areas 【 Display / hide 】

  • Nanotechnology/Materials / Polymer chemistry (Photonics Polymer)

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Research Keywords 【 Display / hide 】

  • Graded Index Plastic Optical Fiber, Zero-Birefringence Polymers

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Books 【 Display / hide 】

  • Fundamentals of Plastic Optical Fibers

    Wiley-VCH, 2015.01

  • 透明ポリマーの材料開発と高性能化

    シーエムシー出版, 2015

    Scope: 第16章　プラスチック光ファイバー

  • Handbook of Fluoropolymer Science and Technology

    Y. Okamoto, F. Mikes, K. Koike, and Y. Koike, Wiley, 2014.05

    Scope: Amorphous Perfluoropolymers

  • 高分子ナノテクノロジーハンドブック～最新ポリマーABC技術を中心として～

    （株）エヌ・ティー・エス, 2014.03

    Scope: 第2章　IT・エレクトロニクスイノベーション：電気電子デバイスの高度化　第5節　フォトニクスポリマーデバイス

  • Optical Fibers; New Developments

    K. Koike, Y. Koike, and Y. Okamoto, Nova Science Publisher, 2013.09

    Scope: Graded-Index Plastic Optical Fibers: Materials and Fabrication Techniques

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Papers 【 Display / hide 】

  • Proposal of novel temperature-independent Zero–Zero-birefringence polymer with high heat-resistance

    Watanabe K., Kobayashi Y., Koike Y.

    IEICE Transactions on Electronics （IEICE Transactions on Electronics)  E104C （ 2 ） 59 - 63 2021.02

    ISSN  09168524

    　View Summary

    Copyright © 2021 The Institute of Electronics, Information and Communication Engineers. Temperature-independent zero–zero-birefringence polymer (TIZZBP), which exhibits very small birefringence over the wide temperature range, is required to realize real-color images for displays, particularly vehicle-mounted displays. Previously, a TIZZBP was synthesized, but they did not put into practical use because of their too complex composition and low mechanical strength. In this paper, we propose a practical TIZZBP that has high heat resistance, high transparency and sufficient mechanical strength, using a simple binary copolymerization system. Our proposed novel polymer exhibits very low photoelastic birefringence and very low orientational birefringence. Both types of birefringence of this TIZZBP satisfy the negligible levels for displays, which are defined as follows: the absolute values of photoelastic coefficient and intrinsic birefringence are less than 1 ×10−12 Pa−1 and 1 ×10−3, respectively. In addition, temperature dependency of orientational birefringence was very low. Orientational birefringence satisfies the negligible level all over the temperature range from around −40◦C to 85◦C. This temperature range is important because it is the operational temperature range for vehicle-mounted display. Furthermore, our proposed novel TIZZBP showed high heat resistance, high transparency and sufficient mechanical strength. The glass transition temperature was 194◦C. The total light transmittance and the haze value is more than 91% and less than 1%, respectively. The tensile strength of non-oriented films was 35 ∼ 50 MPa. These results suggest our proposed novel TIZZBP has high practicality in addition to very low birefringence. Therefore, this TIZZBP film will be very useful for various displays including vehicle-mounted displays and flexible displays.

  • Low-Noise Graded-Index Plastic Optical Fiber Achieved by Specific Copolymerization Process

    Akashi T., Inoue A., Koike Y.

    Journal of Lightwave Technology （Journal of Lightwave Technology)   2021

    ISSN  07338724

    　View Summary

    Ultra-high-definition (UHD) technologies have recently received attention on account of their practical applications in consumer electronics. UHD devices require uncompressed video transmission at a data rate exceeding 100 Gb/s; thus, an optical fiber connection is essential. In consumer applications, optical fibers are very short. Moreover, their connections must permit variations in the fiber alignment, which accommodates rough handling by consumers. Under this condition, the transmitted signal quality is significantly degraded owing to noise and instabilities that strongly depend on the fiber alignment conditions in optical modules and connectors. Therefore, graded-index plastic optical fibers (GI POFs) are promising optical cables for consumer applications because of their flexibility, safety, and high bandwidth. Recently, the authors experimentally demonstrated that GI POFs can reduce interferometric noise, such as modal noise and multipath interference noise, in a multimode fiber link based on a vertical-cavity surface-emitting laser (VCSEL). This noise reduction effect results from strong mode coupling of GI POFs, which is closely related to microscopic heterogeneous structures of a core polymer matrix. In this paper, a control method of mode coupling using the copolymerization process for fiber core materials is proposed. The formation of composition fluctuations by copolymerization increases the mode coupling in the GI POF core. It thereby enables highly stable and robust data transmission with a large fiber misalignment tolerance in a VCSEL-based multimode fiber link. The proposed method for mode coupling control is expected to contribute to household optical communication systems in the upcoming UHD era.

  • Noise and Distortion Reduction in OFDM Radio-Over-Fiber Link by Graded-Index Plastic Optical Fiber

    Muramoto K., Inoue A., Koike Y.

    IEEE Photonics Technology Letters （IEEE Photonics Technology Letters)  32 （ 13 ） 835 - 838 2020.07

    ISSN  10411135

    　View Summary

    © 1989-2012 IEEE. We demonstrate that a graded-index plastic optical fiber (GI POF) enables higher-quality radio-over-fiber (RoF) transmission of an orthogonal frequency-division multiplexing (OFDM) signal, compared with a conventional multimode fiber, for short-distance household applications (< 100 m). It is shown that the improvement in OFDM signal transmission, using the GI POF, can be attributed to the reduction in noise and intermodulation distortion, owing to the external optical feedback from the transmission fibers. The low noise and low distortion in the signal transmission are mainly due to the strong mode coupling in the GI POF, which is closely related to the microscopic heterogeneous structures in core polymer materials. The developed GI POF will be invaluable for RoF networks in households as a solution for indoor broadband wireless communications in the upcoming 5G era.

  • Low-noise radio over graded-index plastic optical fiber

    Inoue A., Koike Y.

    Optics Letters （Optics Letters)  45 （ 12 ） 3192 - 3195 2020.06

    ISSN  01469592

    　View Summary

    © 2020 Optical Society of America We developed a graded-index plastic optical fiber (GI POF) that enables lower-noise radio frequency (RF) transmission than conventional multimode fibers for short-distance household applications (<100 m). It is shown that reflection noise degrades RF transmission, regardless of the carrier frequency, through the spurious generation that accompanies the RF modulation of a vertical-cavity surface-emitting laser. The GI POF with distinctive mode coupling, which is closely related to its microscopic polymer structure, suppresses noise and spurious generation to improve transmission quality. Our low-noise radio-over-GI-POF technology will offer significant advantages for optical wiring systems for broadcast and communication in small- and medium-scale buildings.

  • Reflowable optical connector with glass-ceramic ferrule for advanced pluggable transceiver packaging

    Shikama K., Koike Y.

    Optical Fiber Technology （Optical Fiber Technology)  54 2020.01

    ISSN  10685200

    　View Summary

    © 2019 Elsevier Inc. We describe a new physical-contact optical fiber connector/receptacle that can withstand a solder-reflow process with a maximum temperature of 260 °C for advanced pluggable transceiver packaging such as the co-packaging of photonic and electronic chips using the reflow process. We experimentally clarify the problems that occur in the conventional simplex optical connector through the reflow process while discussing the glass-transition behavior of the adhesive used in the connector. We then present an improved receptacle structure with glass-based ferrules whose coefficients of thermal expansion are closer to that of the fiber compared to the conventional zirconia ferrule. We demonstrate through testing that our proposed receptacle results in a dramatic decrease of permanent fiber withdrawals after the reflow process. The proposed connector, which is composed of a glass-ceramic ferrule, a polyimide tube, and a mechanical clip, achieved physical-contact connection and maintained satisfactory connection and return losses of below 0.3 dB and over 45 dB, respectively, even after six reflow processes. We examined the withdrawal behaviors for both the zirconia and the glass-ceramic ferrules during reflow based on the online measurement of connection and return losses, and observed the multiple reflections caused by the change in the air-gap width between the mated connectors. We also confirmed that the developed simplex optical connectors based on the glass-ceramic ferrule yielded sufficient environmental durability even after multiple reflow processes.

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Reviews, Commentaries, etc. 【 Display / hide 】

  • 屈折率分布型ポリマー光導波路の歴史と展開

    小池康博

    光技術コンタクト (日本オプトメカトロニクス協会)   2017.05

    Article, review, commentary, editorial, etc. (scientific journal), Single Work

  • 新川崎タウンキャンパスの発展とこれからー研究活動を中心に

    小池康博

    三田評論 (慶應義塾)   2016.12

    Article, review, commentary, editorial, etc. (bulletin of university, research institution), Single Work

  • ボールペン技術から生まれたGI-POF用光コネクタ

    三井章仁、小池 康博

    光アライアンス2016年3月号 (日本工業出版)   2016.03

    Article, review, commentary, editorial, etc. (scientific journal), Joint Work

  • ディスプレイの高画質化のための光散乱ポリマー材料

    KOIKE YASUHIRO

    光学 (日本光学会)  44 ( 8 ) 310 - 315 2015.08

    Article, review, commentary, editorial, etc. (scientific journal), Joint Work

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Presentations 【 Display / hide 】

  • 鮮明なリアルカラーディスプレイを実現するためのランダム偏光フィルムの設計

    佐々木詩月、鵜殿真理子、小池康博

    応用物理学会春季学術講演会 (Online) , 

    2021.03
    , 

    Oral presentation (general)

  • 強いモード結合を有する屈折率分布型プラスチック光ファイバのアナログRadio over Fiber伝送特性

    村元謙太、井上梓、小池康博

    電子情報通信学会総合大会 (Online) , 

    2021.03
    , 

    Oral presentation (general)

  • Design of calcite-doped random depolarization films for real-color displays

    S. Sasaki, M. Udono and Y. Koike

    SPIE Photonics West 2021 (San Francisco, USA (Virtual Conference)) , 

    2021.03
    , 

    Oral presentation (general)

  • Low-noise graded-index plastic optical fiber for multi-fiber interconnect

    H. Minami, A. Inoue, and Y. Koike

    SPIE Photonics West 2021 (San Francisco, USA (Virtual Conference)) , 

    2021.03
    , 

    Oral presentation (general)

  • Indoor radio-over-fiber system based on graded-index plastic optical fiber for broadband wireless communication

    K. Muramoto, A. Inoue, and Y. Koike

    SPIE Photonics West 2021 (San Francisco, USA (Virtual Conference)) , 

    2021.03
    , 

    Oral presentation (general)

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Works 【 Display / hide 】

  • 日本経済新聞 15面 低ノイズの光ファイバー　プラ製　慶大と日東電工が開発

    日本経済新聞15面, 

    2020.01
    , 

    Other

  • 電波タイムズ　2面「一般社団法人サービス高度化推進協会が実証実験を公開　新4K8K衛星放送の光配信方式の実用化」

    2019.03
    , 

    Other

  • 電波新聞　3面「A-PAB POFシステムによる実証実験　簡単に現場施工、低コスト　外観損なわず既存設備に追加」

    2019.02
    , 

    Other

  • 日本経済新聞　9面「サングラスでも液晶画面鮮明に　慶大が専用フィルム」

    2019.02
    , 

    Other

  • 日本経済新聞　15面「光ファイバ量産に500億円　日東電工、8K・5G対応」

    2018.05
    , 

    Other

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Awards 【 Display / hide 】

  • Fellow, The Society of Polymer Science, Japan

    Yasuhiro Koike, 2021.08,  The Society of Polymer Science, Japan (SPSJ)

    Type of Award： Honored in official journal of a scientific society, scientific journal

  • 高分子科学功績賞

    小池康博, 2019.02,  The Society of Polymer Science, Japan (SPSJ), フォトニクスポリマーの基礎と機能創出

  • SID Special Recognition Award

    Yasuhiro Koike, 2015.06, The Society for Information Display (SID)

    Type of Award： Award from international society, conference, symposium, etc.,  Country： United States

  • 第２４回「向井賞」

    KOIKE YASUHIRO, 2013.05, 公益財団法人東京応化科学技術振興財団, Fundamental Studies and Creation of Functions of Photonics Polymer

  • 第13回「神奈川イメージアップ大賞」

    KOIKE YASUHIRO, 2011.01, 毎日新聞社

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Courses Taught 【 Display / hide 】

  • GRADUATE RESEARCH ON INTEGRATED DESIGN ENGINEERING 2

    2022

  • APPLIED PHYSICS AND PHYSICO-INFORMATICS LABORATORY C

    2019

  • APPLIED PHYSICS AND PHYSICO-INFORMATICS LABORATORY D

    2019

  • BACHELOR'S THESIS

    2019

  • GRADUATE RESEARCH ON INTEGRATED DESIGN ENGINEERING 1

    2019

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Social Activities 【 Display / hide 】

  • フロンティアサロン財団　理事

    2021.08
    -
    Present

  • 日本板硝子材料工学助成会

    2021.06
    -
    2025.06

  • カイロス株式会社　テクニカル・アドバイザー

    2016.12
    -
    2017.12

  • 第22回微小光学国際会議（MOC'17) 組織委員

    2016.08
    -
    2017.11

  • 国立大学法人　神戸大学　非常勤講師

    2016.08

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Memberships in Academic Societies 【 Display / hide 】

  • The International Society for Optics and Photonics, 

    2016.01
    -
    Present

  • SPIE, 

    2016
    -
    Present

  • The Society for Information Display, 

    2011.04
    -
    Present

  • 一般社団法人　電子情報通信学会, 

    2011.01
    -
    2015.03

  • Japan Responsinble Care Council, 

    2008.10
    -
    2010.05

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Committee Experiences 【 Display / hide 】

  • 2022.08
    -
    2023.03

    国際科学技術共同研究推進事業（戦略的国際共同研究プログラム）アドバイザー, 国立研究開発法人科学技術振興機構

  • 2019.12
    -
    2020.03

    国際科学技術共同研究推進事業（戦略的国際共同研究プログラム）アドバイザー, 国立研究開発法人科学技術振興機構

  • 2018.09
    -
    2018.11

    Organizing Committee Member, the 24th Microoptics Conference (MOC2019)

  • 2018.03
    -
    2022.04

    日本国際賞審査部会委員, 公益財団法人　国際科学技術財団　

  • 2018.02
    -
    2018.03

    国際科学技術共同研究推進事業（戦略的国際共同研究プログラム）アドバイザー, 国立研究開発法人　科学技術振興機構

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