Papers - Koike, Yasuhiro

Synthesis of a Zero-Birefringence Optical Polymer Doped with an Inorganic Birefringent Crystal

H. Ohkita, A. Tagaya, and Y. Koike

Functional Nanomaterials for Optoelectromics and Other Applications 99-100   143 2004

Research paper (international conference proceedings), Joint Work, Accepted

Molecular Characterization of a Amorphous Perfluoropolymer: Poly (perfluoro-2-methylene-4-methyl-1,3-dioxolane)

F. Mikes, I. Teraoka, Y. Koike, and Y. Okamoto

Abstracts of Papers of the American Chemical Society 228   U646 2004

Research paper (international conference proceedings), Joint Work, Accepted

Synthesis and Characterization of Poly (perfluoro-2-methylene-1,3-dioxolanes)

W. Liu, Y. Koike, and Y. Okamoto

Abstracts of Papers of the American Chemical Society 228   U337 2004

Research paper (international conference proceedings), Joint Work, Accepted

Novel Photonics Polymer for Broadband IT

T. Ishigure and Y. Koike

2004 IEEE International Conference on Industrial Technology (ICIT), Vols. 1-3    87 2004

Research paper (international conference proceedings), Joint Work, Accepted

プラスチック光ファイバーとブロードバンド社会

KOIKE YASUHIRO

慶應義塾大学　公開講座 明日の社会と科学技術 (慶應義塾大学、川崎市教育委員会)   2003.12

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低コストで光情報化が可能な高速プラスチック光ファイバーとそのネットワークについて紹介した。更にそれがもたらす現在のインターネットの延長でないリアルタイムのフェイストゥフェイスコミュニケーションの生活と社会のあり方について説明した。

A Novel Perfluoromonomer: Perfluoro-2,3-dihydro-1,4-benzodioxin

WEIHONG LIU, KOIKE YASUHIRO, OKAMOTO YOSHIYUKI

Journal of Fluorine Chemistry Vol. 124 ( Issue 2 ) 183-188 2003.12

Research paper (scientific journal), Joint Work

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A novel perfluoromonomer, perfluoro-2,3-dihydro-1,4-benzodioxin (FDB), was synthesized. The homopolymerization and copolymerizations of FDB were investigated. The structure and physical properties of those polymers were characterized.

超高速伝送・高画質ディスプレイを実現するフォトニクスポリマー

KOIKE YASUHIRO

第27回先端繊維素材研究委員会(AFMc)講演会  2003.11

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これまで行ってきた研究成果を光の偏波（またはフォトン）と高分子物質との係わりという視点で原子系のディメンジョンからマクロな不均質構造にわたって順に述べた。

High-Bandwidth Graded-Index Plastic Optical Fiber Enabling Power Penalty-Free Gigabit Data Transmission

ISHIGURE TAKAAKI, MAKINO KENJI, TANAKA SHO, KOIKE YASUHIRO

Journal of Lightwave Technology Vol. 21 ( No. 11 ) 2923-2930 2003.11

Research paper (scientific journal), Joint Work, Accepted

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A relation between the -3 dB bandwidths of graded-index plastic optical fibers (GI POFs) and the total power penalty of 50-m GI POF links is investigated in detail. The bandwidth of the GI POF is deliberately varied by controlling the index profile. It is theoretically and experimentally confirmed that sufficiently high bandwidth on the order of gigahertz is necessary for the GI POF, even for several hundreds of megabit per second (Mb/s) data rate, in order to achieve the power penalty free in the bit error rate performance of the link. In the case of silica-based multimode fiber links, it has been reported that the launch condition strongly affects the bit error rate performances; hence, a special launching technology for the silica-based multimode fiber is developed to achieve a 1-Gb/s transmission in the gigabit Ethernet protocol. In this paper, it is also found that the power penalty-free state is realized in the GI POF link, which is independent of the launch condition, when a GI POF with a nearly ideal index profile is used. The GI POF is a promising physical layer for realizing stable, high-speed and low-cost data-com networks.

高速光通信・高画質ディスプレイのためのフォトニクスポリマー

KOIKE YASUHIRO

平成15年(2003年)度若手社員のための高分子基礎講座 (社団法人　高分子学会　関東支部)   2003.10

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これまで行ってきた研究成果を光の偏波（またはフォトン）と高分子物質との係わりという視点で原子系のディメンジョンからマクロな不均質構造にわたって順に述べた。

Highly-Efficient Backlight for Liquid Crystal Display Having No Optical Films

OKUMURA TAKAMITSU, TAGAYA AKIHIRO, KOIKE YASUHIRO, HORIGUCHI MASAHIRO, SUZUKI HIROMASA

Applied Physics Letters Vol. 83 ( No. 13 ) 2515-2517 2003.09

Research paper (scientific journal), Joint Work, Accepted

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We propose a highly-efficient backlight that requires no optical films with a polymer containing spherical particles of micron size. The developed backlight is provided with microprisms at the bottom surface, which can reflect directly the incident light into the front direction. The modeling simulation program, employing a Monte Carlo method based on Mie scattering theory, has optimized both the prismatic condition and the multiple scattering characteristics. We confirm that a uniformity of brightness can be achieved without using any optical films, resulting in a high optical efficiency of 62%.

Tacticity Control in The Radical Polymerization of 2,2,2-Trifluoroethyl Methacrylate with Fluoroalcohol

WEIHONG LIU, KAI TANG, YINZHONG GUO, KOIKE YASUHIRO, OKAMOTO YOSHIYUKI

Journal of Fluorine Chemistry Vol. 123 ( Issue 1 ) 147-151 2003.09

Research paper (scientific journal), Joint Work

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The free-radical polymerization of 2,2,2-trifluoroethyl methacrylate (TEMA) was carried out in fluoroalcohols to achieve stereoregulation. The polymerization reactivity at low temperature and syndiotactic specificity were enhanced by the use of fluoroalcohol as a solvent. The polymer having triad syndiotacticity (rr) of 70% was obtained in perfluoro-t-butyl alcohol. It was noted that the stereochemistry was nearly independent of reaction temperature. The stereoeffect of fluoroalcohols seemed to be due to the hydrogen-bonding interaction between the alcohol and the monomer or growing species. The hydrogen-bonding formation was determined by FTIR. The copolymerization of TEMA with methyl methacrylate (MMA) in hexafluoroisopropanol afforded a copolymer with syndiotactic specificity. By this method, a cladding material for an optical fiber based on poly(methyl methacrylate) (PMMA) with high mechanical strength and low refractive index could be obtained.

高画質ディスプレイを支えるフォトニクスポリマー

KOIKE YASUHIRO, TAGAYA AKIHIRO

学術月報 Vol. 56 ( No. 9 ) 61(941)-64(944) 2003.09

Research paper (other academic), Joint Work

Optical Design for The Liquid Crystal Display Backlighting with The Highly Scattering Optical Transmission Polymer

OKUMURA TAKAMITSU, ISHIKAWA TAKESHI, TAGAYA AKIHIRO, KOIKE YASUHIRO

Journal of Optics A: Pure and Applied Optics Vol. 5 ( No. 5 ) S269-S275 2003.09

Research paper (scientific journal), Joint Work, Accepted

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We have developed a highly scattering optical transmission (HSOT) polymer, and have succeeded in applying it to a highly efficient backlight light guide in liquid crystal displays (LCDs). In the present work, a multiple scattering modeling simulation has been developed. Also the effects of adjacent particles inside the HSOT polymer are demonstrated. The numerical calculation, improved by taking account of the adjacent particles, has precisely reproduced the multiple scattering phenomena inside the HSOT polymer. Based upon the results of the multiple scattering analyses, an optimal design has been developed and applied to an LCD backlighting system. By altering the internal particle conditions, uniformity of color and brightness on the top face of the backlight has been achieved.

Compensation of The Birefringence of A Polymer by A Birefringent Crystal

TAGAYA AKIHIRO, OHKITA HISANORI, MUKOH MASAKI, SAKAGUCHI RYUICHI, KOIKE YASUHIRO

Science Vol. 301 ( Issue 5634 ) 812-814 2003.08

Research paper (scientific journal), Joint Work, Accepted

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We report a method for compensating the birefringence of optical polymers by doping them with inorganic birefringent crystals. In this method, an inorganic birefringent material is chosen that has the opposite birefringence to that of the polymer and has rod-shaped crystals that are oriented when the polymer chains are oriented. The birefringence of the polymer is thus compensated by the opposing birefringence of the crystal. Birefringence is minimized in various polymer optical devices by adjusting process conditions, because it degrades the performance of devices. This method minimizes it, independent of process conditions, which potentially improves the productivity of devices.

The Christiansen Effect of Brightly Colored Colloidal Dispersion with An Amphiphilic Polymer

OKOSHI KENTO, NAOKO SANO, OKUMURA TAKAMITSU, TAGAYA AKIHIRO, MAGOSHI JUN, KOIKE YASUHIRO, FUJIKI MICHIYA, WATANABE JUNJI

Journal of Colloid and Interface Science Vol. 263 ( Issue 2 ) 473-477 2003.07

Research paper (scientific journal), Joint Work

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A novel coloration phenomenon in a colloidal dispersion with an amphiphilic polymer was found. The dispersion consists of tetrahydrofuran (THF), an aqueous solution of sodium thiosulfate (Na2S2O3·5H2O), and hydroxypropylcellulose (HPC). The dispersion was emulsified by HPC as an amphiphilic polymer, so that the aqueous phase was confined in droplets in the THF matrix. It typically appeared bluish violet at room temperature and turned into blue with increasing temperature. In this system, the refractive indices of the inside and outside of the droplet coincided at a certain wavelength at which the light passes through without scattering, which is called the Christiansen effect. The color observed was successfully simulated by Mie's scattering theory in combination with the Christiansen effect.

Data transmission over polymer optical fibers

I. T. MONROY, H. P. A. VD BOOM, A. M. J. KOONEN, G. D. KHOE, WATAMABE YUUJI, KOIKE YASUHIRO, ISHIGURE TAKAAKI

Optical Fiber Technology Vol. 9 ( Issue 3 ) 159-171 2003.07

Research paper (scientific journal), Joint Work

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Polymer optical fiber (POF) is a promising transmission medium for providing broadband telecommunication services within the customer's premises. POF offers several attractive features for data transmission such as broad bandwidth and low cost for in-house, access, and LAN applications. This article presents a review on optical transmission systems using POF and their enabling technologies. A summary is given of experimental data links with record capacity over record transmission distances. Standardization activities in POF technology and transmission are reported. To conclude, we discuss trends for further development and research.

Observation of Fluorescence in An Optically Pumped Erbium-Containing Perfluorinated Medium at 1.5 µm

KURIKI KEN, NISHIHARA SUSUMU, NISHIZAWA YUKIHISA, YOSHINAGA TADAHIKO, TAGAYA AKIHIRO, KOIKE YASUHIRO, OKAMOTO YOSHIYUKI

Optics Letters (Optical Society of America)  Vol. 28 ( No.7 ) 570-572 2003.04

Research paper (scientific journal), Joint Work, Accepted

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We report what is to our knowledge the first observation of erbium fluorescence at the optical communication wavelength of 1.5µm in a perfluorinated medium. Using a Nd:YAG (355nm) source, we observed fluorescence of the 4I13/2-4I15/2 transition with a peak wavelength of 1.535µm and with a full width at half-maximum of 28nm. These results can lead to new active devices that use all fluorinated polymers.

Synthesis of A Zero-Birefringence Optical Polymer by the Birefringent Crystal Dopant Method

OHKITA HISANORI, MUKOH MASAKI, TAGAYA AKIHIRO, KOIKE YASUHIRO

Procedings of Material Research Society Symposium / Materials Research Society Spring Meeting, (MRS 2003), (Material Research Society)  Vol. 771   207-211 2003.04

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

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Birefringence induced by orientation of polymer main chains during an injection-molding or extrusion processing restricts the application of optical polymers to optical devices that require maintaining the polarization state of incident light. We propose the "birefringence crystal dopant method" to compensate the birefringence of polymers by homogeneous doping with an opposite birefringent needle-like crystal. Strontium carbonate was selected for this method and synthesized, with particle length of 50-200nm and aspect ratios of 2-5. Strontium carbonate was doped into poly (PMMA/BzMA=78/72(wt. /wt9) film. The film was uniaxcially drawn at 130℃ and 4mm/min. For the first time, the positive birefringence of the drawn copolymer film at a wavelength of 633nm was compensated by doping with 0.3 wt% of Strontium carbonate without losing transparency and thermostability.

Zero-Birefringence Optical Polimer

TAGAYA AKIHIRO, KOIKE YASUHIRO

成形加工/プラスチック成形加工学会誌 (社団法人　プラスチック成形加工学会)  第15 ( 第3 ) 194-198 2003.03

Research paper (other academic), Joint Work

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ポリマー鎖が配向しても複屈折性が生じない「ゼロ複屈折性光学ポリマー」という概念とその有用性について述べ、ゼロ複屈折性光学ポリマーを実現するために新たに提案した「ランダム共重合法」と「異方性低分子ドープ法」について、詳細に紹介する。

高速プラスティック光ファイバーが拓くブロードバンド ―安心とやすらぎの街づくりをめざして―

KOIKE YASUHIRO

Ｋ２タウンキャンパスオープンセミナー (学校法人　慶應義塾大学、川崎市)   2003.02

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現在ＩＴ不況と言われているが、それはソフトに対する期待と、最後の数百メートルのブロードバンド化が進まないハードとのギャップがその一因と考えられている。本セミナーでは、この最後の数百メートルを低コストで光情報化が可能な、高速プラスチック光ファイバーとそのネットワークについて紹介する。更に、それがもたらす現在のインターネットの延長でないリアルタイムの Face to Face Communication の生活と社会の在り方について述べる。