Papers - Koike, Yasuhiro

Application of Highly Scattering Optical Transmission Polymer to LCDs

HORIBE AKIHIRO. KOIKE YAUSHIRO

The Journal of The institute of Electronics,Information and Communication Engineers  ( 3月 ) 17-22 1997.03

Research paper (scientific journal), Joint Work

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We have proposed a new brighter backlight using highly scattering optical-transmission (HSOT) polymer. This polymer material consists of specified microscopic heterogeneous structures inside the polymer. The high order scattering phenomenon in the HSOT polymer was exactly investigated by Monte Carlo simulation based on Mie scattering theory. We obtained a good agreement between the calculated and the experimental results. The scattering property inside the HSOT polymer can be optimized for the LCD backlight by using this simulation program. As the result, our back-light system consisting of the HSOT polymer plate has simpler system, brighter luminance, and better luminance profile. The property of our backlight system which was actually applied to the LCD is shown.

Perfluorinated Polymer GI-POF

KOIKE YASUHIRO, YOSIHARA NORIYUKI, SUGIYAMAHIDENORI, TAKANOYASUNOBU, KOGANEZAWA KOJI, NARITOMI MASAKI

Technical Reporta of IEICE (The Institute of Electronics, Information and Communication Enigineerings)  Vol. 96 ( No. 516 ) 75-80 1997.02

Research paper (other academic), Joint Work

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パーフルオロ非晶質樹脂CYTOPを用いたGI-POFを開発中であり、試作したGI-POFの伝送特性を測定した結果、650-1.300nmの広い波長域で使用でき、長波長では100m以上の伝送が可能であること、および300MHZ・KM以上の高帯域を有していることを実証した。

Estimate of Light Scattering Loss of Amorphous Polymer Glass from Its Molecular Structure

TANIO NORIHISA, KOIKE YASUHIRO

Japanese Journal of Applied Physics Vol.36, part 1 ( No.2 ) 743-748 1997.02

Research paper (scientific journal), Joint Work, Accepted

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The fluctuation theory indicates that the isotropic scattering loss of amorphous polymer glass, which is used as a material for POF, decreased with the decrease in isothermal compressibility β and refractive index. In order to prepare low light-scattering-loss polymer glass, it is necessary to know the isothermal compressibility of polymers. However, the β for most polymers has not yet been measured precisely using a mechanical procedure. In this work, we estimate the isothermal compressibility of amorphous polymer glass from its molecular structure and calculate its isotropic light scattering loss.

High-Power Polymer Optical Fiber Amplifier

KOBAYASHI TAKEYUKI, SASAKI KEISUKE, KOIKE YASUHIRO

The Review of Laser Engineering (The Laser Society of Japan)  Vol.25 ( No.2 ) 153-157 1997.02

Research paper (scientific journal), Joint Work

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In quest of high-power optical amplifier in the visible, we incorporated organic dyes into POFs. Organic dyes were chosen as gain media based on the following features: a large emission cross section, which allows the achievement of high gains in a short length and a broadband fluorescence spectrum that provides wide tunability. A Rhodamine B-doped POFA, 1m in length and 0.3mm in core diameter, has exhibited more than 20dB gain at signal wavelength from 560nm to 600nm when optically pumped at a wavelength of 532 nm. Furthermore, we have obtained the optical amplification covering most of the spectral range from 560 to 650nm. The spectral range in the visible can be continuously covered with the POFAs doped with several selected dyes. The broad spectral coverage demonstrates the versatility of the organic dye-doped POFA.

High-Power and High-Gain Organic Dye-Doped Polymer Optical Fiber Amplifiers:Novel Techniques for Preparation and Spectral Investigation

TAGAYA AKIHIRO, TERAMOTO SHIGEHIRO, NIHEI EISUKE, SASAKI KEISUKE, KOIKE YASUHIRO

Applied Optics Vol.36 ( No.3 ) 572-578 1997.01

Research paper (scientific journal), Joint Work, Accepted

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Rhodamine B (RB), Rhodamine 6G (R6G), Oxazine 4 perchlorate (O4PC), and 4-Dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl-4H-pyran)-doped GI POFAs were successfully prepared by novel technique to prevent degradation of organic dyes and to enhance solubility of the dyes in MMA and in PMMA. High-power and high-gain amplification was achieved for RB-doped GI POFA’s based on the spectral investigation of dyes in PMMA bulk. It should be noted that amplification in the low-loss region of POF was achieved in the R6G- and O4PC-doped GI POFA.

The Plastics

堀部晃啓・小池康博

合成樹脂 (The Japan Society of Plastic Technology)  Vol. 43 ( No. 1 ) 11-12 1997.01

Research paper (other academic), Joint Work

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ポリマー固体内部に不均一構造を有し、光の導波と拡散出射の二つの機能を有する光散乱ポリマー導光体を提案した。またMonte Carlo 法によってその内部の多重散乱現象を理論的に解析し、液晶用バックライトに応用するために最適化を行った。その結果、輝度の均斉度が低下することなく市販品よりも高輝度なバックライトを作製した。（解説）

Present Prospect of Graded-Index Plastic Optical Fiber in Telecommunication

NIHEI EISUKE, ISHIGURE TAKAAKI, TANIO NORIHISA, KOIKE YASUHIRO

IEICE Transactions on Electronics, Vol.E-80-C ( No.1 ) 117-122 1997.01

Research paper (scientific journal), Joint Work

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The status of the POF for high-speed data communication is described. Very recently, the low-loss and high-bandwidth perfluorinated GI POF which has no serious absorption loss from visible to 1.3µm wavelength was successfully prepared at Keio University. Since the core diameter of GI POF is Much larger than that of the multimode silica fiber was virtually eliminates, resulting in stable giga bit order data transmission with inexpensive couplers and connectors.

High Bandwidth Graded-Index Polymer Optical Fiber for Near Infrared Use

E. Nihei, T. Ishigure, and Y. Koike

Applied Optics Vol.35 ( No.36 ) 7085-7090 1996.12

Joint Work, Accepted

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屈折率分布型ポリマー材料に、含フッ素材料を用いることにより、通常の炭素-水素結合からなるポリマーでは伝送損失の値が数100dB/km以上となる、688nmや773nmの近赤外領域の波長において、それぞれ約56dB/kmと約773dB/kmの低損失を実現した。また伝送帯域についても100mで５.12GHzを達成し、これまでのポリマー材料での値よりも約２倍程度優れた値であることを実験的にも確認した。

High Speed POF

KOIKE YASUHIRO, ISHIGURE TAKAAKI, NIHEI EISUKE

Transaction of the Materials Research Society(MRS)of Japan,Transactions (the Materials Research Society(MRS)of Japan)  Vol.22   32-35 1996.12

Research paper (conference, symposium, etc.), Joint Work

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The status of the POF for high-speed data communication is reviewed. Very recently, the low-loss and high-bandwidth perfluorinated GI POF which has no serious absorption loss from visible to 1.3µm wavelength was successfully prepared at Keio University. Since the core diameter of GI POF is much larger than that of the multimode silica fiber, the serious modal noise in the conventional multimode silica fiber was virtually eliminated in stable giga bit order data transmission with inexpensive couplers and connectors.

Amplified Spontaneous Emission in Dye-Doped Polymer Optical Fiber

YAMAMOTO TSUYOSHI, NIHEI EISUKE, SASAKI KEISUKE, KOIKE YASUHIRO

The Joumal of The Institute of Electronics,Information and Communication Engineers,平成8年12月号  ( 12月 ) 13-18 1996.12

Research paper (scientific journal), Joint Work

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ASE in laser dye doped DPOF is investigated experimentally and theoretically. Rate equations on laser intensity with the fluorescence intensity considered is developed to discuss the basic performance of the ASE in the DPOF. The model was useful to explain the experimentally obtained results. In addition, ASE-power on DPOF length dependence, pumping power dependence, pumping wavelength, output spectra, output waveform is evaluated. The maximum energy conversion efficiency obtained form the Rhodamine 6G 5-ppm doped DPOF was about 40%.

プラスチック光ファイバ

KOIKE YASUHIRO

OPTORONICS 15 ( 10 ) 126-132 1996.10

Research paper (other academic), Single Work

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Recently, information service which can be represented by the Internet service have become available to the general households, and a broadband network has been demanded to deliver video services with low cost and easy handling.
Under such circumstances, plastic optical fiber (POF) has been widely studied as the transmission medium of the high-speed information communication network system. The POF can be prepred with a large core diameter because of the high flexibility, which would enable easy connection and branching in the network system. Moreover, the realization of high bandwidth can be achieved by making a graded-nidex type.
In this paper, we report on the process of the studies and development of POF and the present situation of POF.

High-Speed Polymer Optical Fiber -Polymers for high-Speed Information Communication-

KOIKE YASUHIRO

化学と工業/日本化学会誌 (社団法人　日本化学会)  49 ( 10 ) 1379-1381 1996.10

Research paper (other academic), Single Work

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マルチメディア社会で必要な伝送容量をすべてカバーしうる、高速、低損失のポリマー光ファイバーが近年開発され、POFが高速ネットワークやLANの媒体として大きな注目を浴びている。本稿では、POFの特性とその背景について解説する。

Light Scattering Loss and Glass Transition Temperature of Optical Polymer Glass

TANIO NORIHISA, KOIKE YASUHIRO

Kobunshi Ronbunshu,Japanese Journal of Polymer Science and Technology, Vol.53 ( No.10 ) 682-688 1996.10

Research paper (scientific journal), Joint Work

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The glass transition temperature (Tg) was the critical temperature for determining the excess light scattering of PMMA glasses. When PMMA glass is polymerized or heat-treated above the Tg, the excess scattering intensity disappears and the isotropic light scattering loss is reduced to the value calculated from the refractive index and the isothermal compressibility using the thermally induced fluctuation theory. The isotropic light scattering loss of the amorphous polymer can be estimated from its molecular structure by assuming a frozen model around Tg.

New Cladding Polymer for Optical Oxygen Sensor Using Fluorescent Plastic Fiber

MORISAWA MASAYUKI, UCHIYAMA KOJI, HOSAKA TOSHIKI, INOUE HIDEKI, MUTO SHINZO, NAMAZUE AKIRA, NIHEI EISUKE, KOIKE YASUHIRO

SPIE- The International Society for Optical Engineering, Photopolymer Device Physics, Chemistry, and Applications III, Proceedings (SPIE- The International Society for Optical Engineering)  Vol. 2836   336-340 1996.08

Research paper (conference, symposium, etc.), Joint Work

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Improvement of the optical fiber sensor based on the fluorescence quenching by oxygen gas was studied. Using the newly synthesized PMtMA and its blend of the PMtMA/PMP as the cladding layer, in which sensing dye was doped, the POF O2 sensor with high sensitivity and a fast response time could be realized. In addition, this sensor didn’t receive any affect by humidity.

Phase-Matched Operation of Polymer TE-TM Mode Converter

MUTO SHINZO, SAKAGAMI TOMOYASU, YOSHIHIKO SAKANE, NAMAZUE AKIRA, NIHEI EISUKE, KOIKE YASUHIRO

SPIE- The International Society for Optical Engineering, Photopolymer Device Physics, Chemistry, and Applications III, Proceedings (SPIE- The International Society for Optical Engineering)  Vol. 2851   105-109 1996.08

Research paper (conference, symposium, etc.), Joint Work

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A novel TE-TM mode converter using optical active polymers (OAPs), which can be fabricated much more easily than the conventional ones, was proposed. To achieve its phase-matched operation, two methods for controlling birefringence in the OAP waveguides were studied and hence TE0-TM0 mode convention with a high efficiency of about 70% was obtained for the first time.

New Cladding Polymer for Optical Oxyzen Sensor Using Fluorescent Plastic Fiber

M. Morisawa, K. Uchiyama, T. Hosokawa, H. Inoue, S. Muto, A. Namazue, E. Nihei, and Y. Koike

Proceedings of SPIE-The International Society for Optical Engineering / Chemical,Biochemical,and Environmental Fiber SensorsVlll Vol.2836   336-340 1996.08

Research paper (conference, symposium, etc.), Joint Work

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ポリメンチルメタクリレートをクラッド層にコーティングすることにより,これまで作製されていた蛍光ポリマー光ファイバー型酸素センサーの感度を大幅に向上させることに成功した。

Phase-Matched Operation of Polymer TE-TM Mode Converter

S. Muto, T. Sakagami, Y. Sakane, A. Namazue, E. Nihei, and Y. Koike

Proceedings of SPIE-The INternational Society for Optical Engineering / Photopolymer Device Physics, Chemistry, and ApplicationsⅢ Vol.2851   105-109 1996.08

Research paper (conference, symposium, etc.), Joint Work

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ポリマーTE-TMモード変換器の位相整合動作について述べた。

Compensation for Birefringence of Oriented Polymers by Random Copolymerization Method

IWATA SHUICHI, TSUKAHARA HISASI, NIHEI EISUKE, KOIKE YASUHIRO

Japanese Joumal of Applied Physics Vol.35,Part1, ( No.7 ) 3896-3901 1996.07

Research paper (scientific journal), Joint Work, Accepted

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Birefringence is caused by orientation of polymer during injection molding or extrusion, and is a large obstacle to optical applications. Transparent Zero-birefringence copolymers were successfully synthesized by randomly copolymerizing two monomers having positive and negative birefringence, respectively. Since the anisotropic polymerization of the negative birefringence monomer units is compensated by the positive birefringent monomer units on the same polymer chain, the birefringence is compensated on the length scale of only several monomer units and becomes zero for any degree of orientation. MMA was used as the negative birefringent monomer, and 3FMA as the positive birefringent monomer. Poly (MMA-co-3FMA) copolymer synthesized with a composition of MMA/3FMA=45/55 (wt/wt) shows no birefringence for any draw ratio when a sample film was 65.9dB/km, which is comparable to those of homopolymers.

マルチメディアのための高速プラスチック光ファイバー

KOIKE YASUHIRO

三田評論 (慶應義塾)   ( 980 ) 34-40 1996.05

Research paper (other academic), Single Work

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広伝送帯域を実現する屈折率分布型ポリマー光ファイバーの解説。

Optimum Refractive-Index Profile of The Graded-Index Polymer Optical Fiber, Toward Gigabit Data Links

ISHIGURE TAKAAKI, NIHEI EISUKE, KOIKE YASUHIRO

Applied Optics Vol.35 ( No.12 ) 2048-2053 1996.04

Research paper (scientific journal), Joint Work, Accepted

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The Optimum refractive index distribution of the high-bandwidth GI POF was clarified for the first time by consideration of both modal and material dispersion. The ultimate bandwidth achieved by the POF is investigated by a quantitative estimation of the material dispersion as well as the modal dispersion. The results indicate that even if the refractive index is tightly controlled, the bandwidth of the GI POF is dominated by the material dispersion when the required bit rate becomes larger than a few gigabits per second. It is also confirmed that the material dispersion strongly depends on the matrix polymer and that the use of PMMA allows for a 10Bb/s signal transmission.