Details of a Researcher - Koike, Yasuhiro

Papers - Koike, Yasuhiro

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Scattering Polanzer with Anisortropic Crystals in Polyolefin Polymer

OKUMURA TAKAMITSU, ISHIKAWA TAKESHI, TAGAYA AKIHIRO, KOIKE YSUHIRO

Applied Physics Letters Vol.82 ( No.4 ) 496-498 2003.01

Research paper (scientific journal), Joint Work, Accepted

A scattering polarizer containing carbonate whiskers (aragonite) in a polyolefin polymer has been developed. A selective multiple scattering technique, generating transmitted linearly polarized light and backward scattered light, has been demonstrated. A refractive index match and mismatch arise from the uniaxial orientation of the host polymer and the alignment of aragonite in the drawing direction. The dependence of the transmittance on the polarization direction of the incident light has been observed. The polarization efficiency has been measured to be 60% with a 150µm thickness.

Fundamentals for Me

KOIKE YASUHIRO

Fuji 21c Forum (Teijin Group) 2003.01

Single Work

ITのためのナノファイバー(GI系光ファイバーと表示デバイス)

KOIKE YASUHIRO

ナノファイバー勉強会 2003.01

Single Work

Nano-Fiber for IT High Speed Data Transmission and High Quality Display -

KOIKE YASUHIRO, ISHIGURE TAKAAKI, TAGAYA AKIHIRO

Fiber (The Society of Fiber Science and Technology, Japan) Vol.59 ( No.1 ) 12-17, 2003, 2003.01

Research paper (other academic), Joint Work

Novel Photonics Polymer for IT-High Speed Data Transmission and High Quality Display-

KOIKE YASUHIRO

Special Seminar on POF MIT, (Boston, USA) 2002.11

Research paper (other academic), Single Work

Optical Network Evolution in Asia-Plastic Optical Fiber (POF) and Keio University

石槫崇明、小池康博

Optical Networks World Asia 2002 (Raffles City, Singapore) 2002.09

Joint Work

私の心に残る論文 Scattering by an Inhomogeneous Solid

KOIKE YASUHIRO

高分子/高分子学会誌 (The Society of Polymer Science, Japan) 51 ( 9月 ) 737 2002.09

Research paper (other academic), Single Work

ブロードバンド光ネットワークと新しいライフスタイル

KOIKE YASUHIRO

慶應工学会設立40周年記念会 (財団法人　慶応工学会) 2002.09

Single Work

Graded-Index Polymer Optical Fiber with High Temperature and High Humidity Stability.

ISHIGURE TAKAAKI, SATO MASATAKA, KONDO ATSUSHI, TUKIMORI YASUYUKI, KOIKE YASUHIRO

IEEE Journal of Lightwave Technology Vol.20 ( No.10 ) 1818-1825 2002.08

Research paper (scientific journal), Joint Work, Accepted

It was clarified for the first time that the slight attenuation increment observed in the previous PMMA dopant system GI POF we reported originated in the excess scattering loss induced by the aggregation of absorbed water into toe POF. Although, the PMMA material generally absorbed two weight% of water at maximum, the low attenuation of the conventional SI POF whose core material is PMMA can be maintained at 70℃, 80% relative humidity (RH) atmosphere because the absorption water might be homogeneously dispersed without any aggregation in the core of POF. On the other hand, addition of dopant material having higher refractive index than that of PMMA is required to form the refractive index distribution in the GI POF, which decreases the amount of water absorption into polymer, because the dopant material is more hydrophobic than PMMA. Therefore, in spite of the small amount of absorbed water such as 0.5wt%, the absorbed water molecules can not be uniformly dispersed but must be aggregated to form heterogeneities in the refractive index of the polymer matrix. It was clarified that a dopant materials that is as hydrophilic as PMMA-dopant system GI POF under high temperature and high humidity atmosphere, and such a suitable dopant system GI POF was proposed.

Spectroscopic Properties of Lanthanide Chelates in Perfluorinated Plastics for Optical Applications

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

Journal of The Optical Society of America B (Optical Society of America) Vol.19 ( No.8 ) 1844-1848 2002.08

Research paper (scientific journal), Joint Work, Accepted

The absorption spectra of neodymium (Nd), praseodymium (Pr), erbium (Er), and thulium (Tm) ions in perfluorinated (PF) plastic solutions were measured, and the Judd-Ofelt parameters of the Er and Nd ions have been calculated. The radiative properties of the Nd and Er ions in PF plastic solutions were determined from the absorption measurements and the Judd-Ofelt theory. The fluorescence spectrum of Nd^3+ in a PF plastic solution from 900 nm to 1350 nm was measured for the first time, to our knowledge. Furthermore, the PF plastic films containing lanthanide chelates were fabricated by spin coating, and the refractive indices of the films were measured.

High-Bandwitch Graded-Index Polymer Optical Fiber with High Temperature Stability

ISHIGURE TAKAAKI, SATO MASATAKA, KONDO ATSUSHI, KOIKE YASUHIRO

IEEE Journal of Lightwave Technology Vol.20 ( No.8 ) 1443-1448 2002.08

Research paper (scientific journal), Joint Work, Accepted

A new developed GI POF with high-temperature and high-humidity stability was proposed. As it was found that the high numerical aperture and high glass transition temperature (Tg) at the core center of the GI OPF were key issue to achieve both high-temperature and humidity stability, a partially fluorinated polymer material was adopted to obtain both characteristics in the GI POF. The newly developed GI POF had low-loss, high-bandwidth, high-temperature and humidity stability at 70℃, 80% relative humidity (R.H.) and low bending loss.

Accurate Refractive Index Profiling in A Graded-Index Plastic Optical Fiber Gigabit Transmission Rates.

ISHIGURE TAKAAKI, TANAKA SHO, KOBAYASHI EIJI, KOIKE YASUHIRO

IEEE Journal of Lightwave Technology Vol.20 ( No.8 ) 1449-1456 2002.08

Research paper (scientific journal), Joint Work, Accepted

An optimum index profile offering the highest bit rate communication was formed in a PMMA based GI-POF by modifying the polymerization process. The interfacial gel polymerization process we have proposed to fabricate the PMMA-based GI-POF is capable of forming a nearly optimum refractive index profile. However, the theoretically calculated bandwidth from the measured index profile was reduced compared with the GI POF having optimum index profile. In this paper, we report how to obtain a PMMA-based GI POF having exactly the optimum index profile. The bandwidth of this ideal GI POF was experimentally measured and the very high bandwidth of 2.88GHz even for a 150m fiber length was confirmed. The calculated bandwidth agreed well with experimentally measured one. These results indicate that very low modal dispersion can be expected in a GI POF fabricated by the modified interfacial-gel polymerization process.

高速ネットワークアイランド構想とライフスタイル

KOIKE YASUHIRO

多摩美術大学特別講演 (多摩美術大学) 2002.06

Single Work

Broadband Network Realized with Polymer Optical Fiber

ISHIGURE TAKAAKI, KOIKE YASUHIRO

高分子/高分子学会誌 (The Society of Polymer Science, Japan) 51 ( 6月 ) 451 2002.06

Research paper (other academic), Joint Work

Plastic Optical Fiber Lasers and Amplifiers Containing Lanthanide Complexes

KURIKI KEN, KOIKE YASUHIRO, OKAMOTO YOSHIYUKI

Chemical Reviews Vol.102 ( No.6 ) 2347-2356 2002.05

Research paper (scientific journal), Joint Work, Accepted

High Efficiency Optical Coupler for A Small Photo Acceptance Area Photodiode Used in The High Speed Plastic Optical Fiber Communication

MATSUMOTO YOSHIHNORI, NAKAZONO AKIMICHI, KITAHARA TAISUKE, KOIKE YASUHIRO

Sensors And Actuators A: Physical Vol. 97-98 318-322 2002.04

Research paper (other academic), Joint Work

A high efficiency optical coupler has been developed for high speed plastic optical fiber communication. The coupler was designed for a small photo acceptance area photodiode based on the shape of compound parabolic concentrator. The theoretical efficiency of the coupler for graded index plastic optical fiber (GI-POF) was simulated with ray trace simulation, and the coupling loss was calculated less than 0.4 dB. The coupler was batch fabricated in a glass substrate using sand blast technique. The reflection layer of reflectance 90% was formed by Gold/Nickel mirror plating method. The coupler was bonded with a custom designed high speed PIN photodiode. The photocurrent was 20% higher than the current of a ball lens type PIN photodiode. The cut-off frequency was over 1 Gbps at reverse bias of 1.5 V.

The Advanced Highly Scattering Optical Transmission Polymer Backlight for Liquid Crystal Displays

TAGAYA AKIHIRO, ISHII SUGURU, YOKOYAMA KAZUAKI, HIGUCHI EIZABURO, KOIKE YASUHIRO

Japanese Joumal of Applied Physics Vol.41, Part 1 ( No.4A ) 2241-2248 2002.04

Research paper (scientific journal), Joint Work, Accepted

We have demonstrated that the advanced highly scattering optical transmission (HSOT) polymer backlight that was designed by the HSOT designing simulation program. This backlight exhibited approximately three times higher luminance and 20% higher efficiency than the conventional flat type HSOT backlight of 14.1inch diagonal because of the microscopic prism structures at the bottom of the advanced HSOT light guide plate. The HSOT polymer containing the optimized heterogeneous structures produced homogeneous scattered light with forward directivity and sufficient color uniformity. Optimization of the heterogeneous structure is important in order to utilize the taper effect and the microscopic prism structure.

高速POFによるブロードバンドネットワーク

KOIKE YASUHIRO, ISHIGURE TAKAAKI

JEITA Review/電子情報技術産業協会機関紙 (社団法人　電子情報技術産業協会) ( 1月 ) 7-15 2002.01

Research paper (other academic), Single Work

Plastic Optical Fibers Containing Lanthanide Chelates and Organic Dyes for Laser and Amplifier Applications

KURIKI KEN, NISHIHARA SUSUMU, TAGYA AKIHIRO, KOIKE YASUHIRO, OKAMOTO YOSHIYUKI

Proceedings of The International Society of OpticalEngineering, (SPIE) / Organic Photonic Materials and Devices IV (SPIE The International Society for Engineering) Vol. 4642 62-70 2002.01

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

Absorption spectra of lanthanide ions in perfluorinated (PF) plastic solution were measured, and the radiative properties were determined by the absorption measurements and the Judd-Ofelt theory. Fluorescence spectrum of Nd3+ in PF plastic solution from 900nm-1350nm, pumped at 580 nm, were measured for the first time. Lasting properties of a Rhodamine 6G-doped graded-index plastic optical fiber laser (GI POFL) and rod laser were investigated. All measurements demonstrated the superior performance of the GI POFL. This paper also discusses the lasing properties on the basis of near-field pattern measurements.

Thin Liquid-Crystal Display Backlight System with Highly Scattering Optical Transmission Polymers

TAGAYA AKIHIRO, NAGAI MICHIO, KOIKE YASUHIRO, YOKOYAMA KAZUAKI

Applied Optics Vol. 40 ( No. 34 ) 6274-6280 2001.12

Research paper (scientific journal), Joint Work, Accepted

We described an advanced highly scattering optical transmission (HSOT) polymer backlight system that has shown twice the brightness of a conventional transparent system in spite of its having a thinner backlight. The HSOT polymer that contains optimized heterogeneous structures produced homogeneous scattered light with forward directivity and sufficient color uniformity. Although it was thought that polymers for light-guide plates (LPGs) must be transparent to minimize scattering, we have come to the conclusion that HSOT polymer, which is not an absorbing medium but a scattering medium, is a more suitable medium for LPGs.

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