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 】

  • Random depolarization film design for real-color displays

    Sasaki S., Udono M., Koike Y.

    Applied Optics (Applied Optics)  61 ( 3 ) 669 - 675 2022.01

    ISSN  1559128X

    　View Summary

    Liquid crystal displays and organic light-emitting diode displays emit polarized light through polarizers and quarter-wave plates, which cause blackout and color change problems when the displays are viewed through polarizers, such as polarized sunglasses. Random depolarization films (RDFs) are polymer films doped with calcite particles, which randomize the polarization of light emitted from displays to resolve polarization problems. To realize displays without any color change, we investigate the retardation values and fabrication conditions required for RDFs. Analysis of the transmittance spectra and interference colors of different RDFs suggested that retardation values of approximately 600–1200 nm are sufficient to realize real-color displays. In addition, the color change measurements of displays with the RDFs revealed that an optimal dopant particle size exists and that the RDFs doped with 3.6 and 7.3 µm calcite particles achieved chromaticity changes of less than 0.02 for all 24 colors in the Macbeth chart.

  • Error-free PAM-4 transmission by a high-speed plastic optical fiber without forward error correction

    Koike Y., Muramoto K.

    Optics Letters (Optics Letters)  46 ( 15 ) 3709 - 3712 2021.08

    ISSN  01469592

    　View Summary

    This Letter reports, to the best of our knowledge, the first study in which error-free four-level pulse-amplitude modulation (PAM-4) transmission has been achieved using a graded-index plastic optical fiber (GI POF) without the use of forward error correction (FEC) techniques, at a high data rate (>50 Gb/s), for short-reach applications (10 m). The GI POF that is developed has the characteristic microscopic heterogeneities in the fiber core material, which provide distinct mode coupling and significantly stabilize PAM-4 data transmission. The results of the study in this Letter indicate that the GI POF achieves highly stable PAM-4 transmission without the need for the current FEC techniques, which seriously increase the communication delay and power consumption of the transmission systems. Our GI POF material is paving the way for “material changes the system” approaches for achieving unprecedented optical interconnects in real time at a high speed and with low power consumption.

  • Real-color displays realized by randomized polarization

    Sasaki S., Udono M., Koike Y.

    Applied Optics (Applied Optics)  60 ( 11 ) 3108 - 3113 2021.04

    ISSN  1559128X

    　View Summary

    This study achieves real-color displays using a randomizing effect based on the concept of "natural light."At present, most displays emit linearly polarized light, which causes essential blackout and color degradation problems when the displays are viewed through polarizers such as sunglasses. To address this, complex polarization-control technologies are added to existing displays, but the problems remain unresolved. In contrast, this study randomizes the polarization using a polymer film called a random depolarization film (RDF) that is doped with specific birefringent crystal particles. The RDF placed on a display reproduces colors that are very close to the natural colors seen in reality without the need for complex polarization technologies.We believe that it has the potential to change the approach to color-reproducing technology for displays.

  • 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.

  • Design of random depolarization film with random retardation for real-color displays

    Sasaki S., Udono M., Koike Y.

    Digest of Technical Papers - SID International Symposium (Digest of Technical Papers - SID International Symposium)  52 ( 1 ) 1283 - 1286 2021

    ISSN  0097966X

    　View Summary

    Our proposal, the random depolarization film (RDF) is highly efficient in preventing color change problem of LCD and OLED displays. We designed the RDF that realizes real-color displays by considering the retardation. The RDF with random retardation above 600 nm achieved much lower color change that human eyes cannot recognize.

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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 】

  • APS TV 2023 Highligh Research

    2023.03
    -
    Present

  • 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

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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

  • 2019年度高分子科学功績賞

    小池康博, 2020.05,  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

    2023

  • GRADUATE RESEARCH ON INTEGRATED DESIGN ENGINEERING 2

    2022

  • BACHELOR'S THESIS

    2019

  • GRADUATE RESEARCH ON INTEGRATED DESIGN ENGINEERING 1

    2019

  • GRADUATE RESEARCH ON INTEGRATED DESIGN ENGINEERING 2

    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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