Details of a Researcher - Koike, Yasuhiro

Papers - Koike, Yasuhiro

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High Temperature Resistant Graded-Index Polymer Optical Fiber

SATO MASATAKA, HIRAI MIKI, ISHIGURE TAKAAKI, KOIKE YASUHIRO

Journal of Lightwave Technology, Vol.18 ( No.12, ) 2139-2145 2000.12

Research paper (scientific journal), Joint Work, Accepted

The dopant system GI POF for high temperature stability both in bandwidth and in attenuation is reported for the first time. We confirmed that the Numerical Aperture (NA) of the GI POF strongly influences the temperature stability of the GI POF in the attenuation. It was confirmed in this paper that the attenuation increment was mainly induced by the bending loss, since the GI POF drawn by high tension tended to show its length shrinkage, resulting in irregular bending due to the orientation relaxation of polymer chain. We clarified optimum drawing tension which maintains high mechanical properties and minimize the length shrinkage of the GI POF at high temperature, and the optimum fabrication conditions of the GI POF for high temperature stability both in bandwidth and in attenuation.

Organic Dye-Doped Polymer Optical Fiber Lasers

KURIKI KEN, KOBAYASHI TAKEYUKI, IMAI NANA, TAMURA TOSHIHIKO, KOIKE YASUHIRO, OKAMOTO YOSHIYUKI

Polymers for Advanced Technologies, Vol.11, ( Issue, 8-12 ) 612-616 2000.11

Research paper (scientific journal), Joint Work

We report on the lasing action of the graded-index polymer optical fibers containing dyes, such as Rhodamine B, Rhodamine 6G, Perylene orange and Pyrromethene 567. These dyes have been incorporated into poly(methyl methacrylate-co-2-hydroxyethyl methacrylate). These fibers were transversely pumped at 532 nm with a frequency-doubled Q-switched Nd-YAG laser. Slope efficiency of 24% and output of 1.2 mJ were obtained with a Rhodamine 6G-doped fiber. Lifetime of 200,000 pulses at 10 Hz was achieved with a Rhodamine B-doped fiber.

Fundamentals and Creative Research and Development of Photonics Polymer

KOIKE YASUHIRO

繊維と工業/繊維学会誌 (社団法人　繊維学会) Vol. 56 ( No. 10 ) 277-281 2000.10

Research paper (other academic), Single Work

プラスチック光ファイバ最近の話題

ISHIGURE TAKAAKI, KOIKE YASUHIRO

Optp News (Optical Industry and Technology Development Association) 通 ( 119 ) 38-42 2000.09

Research paper (scientific journal), Joint Work

Fabrication and Properties of Polymer Optical Fibers Containing Nd-Chelate

KURIKI KEN, KOBAYASHI TAKEYUKI, IMAI NANA, TAMURA TOSHIHIKO, NISHIHARA SUSUMU, TAGAYA AKIHIRO, KOIKE YASUHIRO, OKAMOTO YOSHIYUKI

IEEE Photonics Technology Letters, Vol.12 ( No.8, ) 989-991 2000.08

Research paper (scientific journal), Joint Work, Accepted

High-Efficiency Organic Dye-Doped Polymer Optical Fiber Lasers

KURIKI KEN, KOBAYASHI TAKEYUKI, IMAI NANA, TAMURA TOSHIHIKO, NISHIHARA SUSUMU, NISIZAWA YUKIHISA, TAGAYA AKIHIRO, KOIKE YASHUIRO, OKAMOTO YOSHIYUKI

Applied Physics Letters, Vol.77 ( No.3 ) 331-333 2000.07

Research paper (scientific journal), Joint Work, Accepted

Which is A More Serious Factor to The Bandwidth of GI POF: Differential Mode Attenuation or Mode Coupling?

ISHIGURE TAKAAKI, KANO MARIKO, KOIKE YASUHIRO

Journal of Lightwave Technology, (IEEE) Vol.18 ( No.7 ) 959-965 2000.07

Research paper (scientific journal), Joint Work, Accepted

It is clarified for the first time that the effect of the mode coupling on the bandwidth characteristics is very small in the GI POF compared with in the SI POF. Although there have been several trials regarding the theoretical prediction of bandwidth characteristics of GI POF, a disagreement between measured and estimated properties was observed. The origin of disagreement has bees generally explained as the mode coupling effect. However, it is clarified in this paper that the effect of differential mode attenuation is the dominant factor of disagreement between measured and predicted bandwidth characteristics, while the effect of the mode coupling is small. In order to clarify the reason why the calculated bandwidth characteristics of the GI POF shows a disagreement with that measured, differential mode delay and differential mode attenuation were investigated. It was found that the highest order mode in the PMMA based GI POF attenuated 17dB compared with the lowest order mode through 100m transmission. By taking into account this differential mode attenuation, an excellent agreement is observed between calculated and measured result of both the bandwidth characteristics and group delay, in which no mode coupling was considered.

POF: Friendly and the Highest Bandwidth

KOIKE YASUHIRO, ISHIGURE TAKAAKI

高分子/高分子学会誌 (The Society of Polymer Science, Japan) 49 ( 7月 ) 431-434 2000.07

Research paper (other academic), Joint Work

High-Speed Plastic Optical Fibers

SATO MASATAKA, ISHIGURE TAKAAKI, KOIKE YASUHIRO

Science and Technology in Japan, ( No.74 ) 15-27 2000.07

Research paper (other academic), Joint Work

Thermally Stable High-Bandwidth　Graded-Index Polymer Optical Fiber

SATO MASATAKA, ISHIGURE TAKAAKI, KOIKE YASUHIRO

Journal of Lightwave Technology, (IEEE) Vol.18 ( No.7 ) 952-958 2000.07

Research paper (scientific journal), Joint Work, Accepted

High bandwidth PMMA based GI POF with high thermal stability is proposed. No distortion of bandwidth was observed even after more than 10000 hours aging at 85℃ by selecting the large size aromatic dopant which has the stable secondary interaction with PMMA matrix and maintains the high glass transition temperature (Tg) of the core of GI POF. The relationship between the heat-drawing condition from the GI preform to the fiber and the thermal stability in the attenuation was investigated. It was clarified that the length shrinkage of the fiber during the aging at high temperature caused large attenuation increase. On the other hand, the degree of shrinkage could be tightly controlled by changing the heat-drawing tension. It was confirmed that the GI POF drawn with optimized heat-drawing tension had no shrinkage of the fiber during aging at 70℃ and no attenuation increase was observed.

ポリマー光ファイバー増幅器・レーザー

A. Tagaya, K. Kuriki, Y. Koike

光学/日本光学会誌 (Optical Society of Japan, (An Affiliate of the Japan Society of Applied Physics)) 29 ( 4 ) 237(39)-242(44) 2000.04

Research paper (other academic), Joint Work

Recent Status of High-Speed Polymer Optical Fiber and Its Future Prospect

ISHIGURE TAKAAKI, KOIKE YASUHIRO

Laser and Quantum Electronics (社団法人　電子情報通信学会) Vol. 99 ( No. 652 ) 31-36 2000.02

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

A lot of research interests are focused on the introduction of optical fiber even in the access network because of the growing demand for accessing Internet with high bit rate. Since inexpensive total system cost is strong]y required for LAN or access network, we have proposed a large-core, low-loss and high-bandwidth graded-index polymer optical fiber (GI POF) as a promising candidate of physical media. In this paper, we describe the recent development of the GI POF in its attenuation and bandwidth achieved by investigating a new polymer material and by theoretical analysis.

Optimum Index Profile of The Perfluorinated Polymer-Based GI Polymer Optical Fiber and Its Dispersion Properties

ISHIGURE TAKAAKI, KOIKE YASUHIRO, JAMES W. FLEMING

Journal of Lightwave Technology Vol. 18 ( No. 2 ) 178-184 2000.02

Research paper (scientific journal), Joint Work, Accepted

The significant advantages in bandwidth and low material dispersion of perfluorinated (PF) polymer-based GI POF are theoretically and experimentally reported for the first time. It is confirmed that the low attenuation and low material dispersion of the PF polymer enables 1 Gb/s km and 10Gb/s km transmission at 0.85µm and 1.3µm wavelength, respectively. The PF polymer-based GI POF has very low material dispersion, compared with those of the conventional PMMA-based POF and of multimode silica fiber. Since the PF polymer-based GI POF has low attenuation from the visible to near infrared region, not only the 0.65µm wavelength which is in the low attenuation window of the PMMA-based POF, but other wavelength such as 0.85µm or 1.3µm etc. can be adopted for the transmission wavelength. It is clarified in this paper that wavelength dependence of the optimum index profile shape of the PF polymer-based GI POF is very small, compared to that of silica-based multimode fiber. As a result, the PF polymer based GI POF has greater tolerance in index profile variation for higher speed transmission than multimode silica fiber. The impulse response function of the PF polymer-base GI POF was accurately analyzed from the measured refractive index profile using a Wentzel, Kramers, Brillouin (WKB) numerical computation method. By considering all dispersion factors involving the profile dispersion, predicted bandwidth characteristics of the PF polymer-based GI POF agreed well with that experimentally measured.

High-Performance Polymer Optical Fiber Lasers and Amplifiers

KURIKI KEN, KOBAYASHI TAKEYUKI, TAMURA TOSHIHIKO, TAGYA AKIHIRO, KOIKE YASUHIRO, OKAMOTO YOSHIYUKI

Proceedings of SPIE The Society for Optical Engineering / Photonics West, Optelectronics 2000, Technical Conference on Organic Photonics Materials and Devices II (The International Society for Optical engineering (SPIE)) Vol. 3939 28-38 2000.01

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

We report on the lasing action of the GI POF containing dyes, such as Rhodamine B, Rhodamine 6G, Perylene Orange, and Pyrromethene 567. These dyes have been incorporate into poly (methyl methacrylate-co-2-hydroxyethyl methacrylate). These fibers were transversely pumped at 532 nm with a frequency-doubled Q-switching ND: YAG laser. Slope efficiency of 24% and output of 1, 3 mJ was obtained with a Rhodamine 6G-doped fiber. A Lifetime of 200,000 pluses at 10 Hz was achieved with a Rhodamine B-doped fiber.
GI POF containing a Nd-chelate has also been fabricated. The absorption spectrum of the fiber exhibited several strong bands in the visible and infrared region. We have observed infrared fluorescence (0.90, 1.60, and 1.3µm) of the Nd3+ ion of the fiber at room temperature when it was pumped with an Ar+ -pumped dye laser at 580 nm. The Judd-Often theory was applied to the absorption spectrum of Nd+ in polymer to determine the Judd-Ofelt parameters. From the theory, various radiative properties, such as transition probability, branching ratio, and emission cross section for various emission levels, have been determined and reported.

Rare Earth-Doped Graded Index Polymer Optical Fibers for Optical Amplification

TAKEYUKI KOBAYASHI, KURIKI KEN, NISHIHARA SUSUMU, KOIKE YASUHIRO, OKAMOTO YOSHIYUKI

Proceedings of SPIE, The Society for Optical Engineering / Photonics West, Technical Conference, Rare-Earth-Doped Materials and Devices IV (The International Society for Optical Engimeering (SPIE)) Vol. 3942 158-165 2000.01

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

光通信と情報家電の動向

KOIKE YASUHIRO, ISHIGURE TAKAAKI

Promoting Machine Industry in Japan (Japan Society for The Promoting of Machine Industry) ( 通巻380号、 ) 65-71 2000.01

Research paper (other academic), Joint Work

What is The Most Transparent Polymer?

TANIO NORIHISA, KOIKE YASUHIRO

Polymer Journal (The Society of Polymer Science, Japan) Vol.32 ( No.1, ) 43-50 2000.01

Research paper (scientific journal), Joint Work, Accepted

The development of POF leads to the fundamental question about the transmission loss limit of amorphous polymer glasses. The two intrinsic loss factors of amorphous POFs are molecular visible absorption and scattering due to fluctuation. In this paper, we have investigated the lower limit of the inherent light transmission loss of amorphous polymer glass from its molecular structure by using the Morse potential theory for absorption and the fluctuation theory for scattering. The theoretical lower limit of the attenuation of the amorphous perfluoropolymer is 0.3µm, and is comparable with that of silica fiber. Amorphous perfluoropolymer seems to be a most transparent polymer.

New Highly Scattering Optical Transmission Polymers for LCD Backlight

TAGAYA AKIHIRO, KOIKE YASUHIRO

Optical and Electro-Optical Engineering Contact (Japan Optoelectron-Mechanics Association (JOEM)) Vol. 38 ( No. 1 ) 47-55 2000.01

Research paper (other academic), Joint Work

Slab Waveguide-Type Optical Modulators Using Optically Active and Nonlinear Polymers

MUTO SHINZO, TATSUZAWA YUKIYASU, ISHIYAMA KIYOSHI, KOIKE YASUHIRO

Nonlinear Optics Vol. 22 449-452 1999.11

Research paper (other academic), Joint Work

Highly Scattering Optical Transmission Polymers for Liquid Crystal Display

TAGAYA AKIHIRO, KOIKE YASUHIRO

Proceedings of SPIE The Society for Optical Engineering / International Symposium on Photonics and Applications (ISPA’99), COnference on Design,Fabrication,and Characterization of Photonic Devices Vol. 3896 214-222 1999.11

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

We proposed highly scattering optical transmission (HSOT) polymers and applied it to a light pipe of a backlighting system for liquid crystal displays (LCDs). The HSOT polymer backlighting system having not only approximately twice the brightness but also twice the efficiency of the conventional one was realized based on analysis of multiple scattering in the HSOT polymers. The problem of color dispersion which had been believed to be the nature of scattering phenomenon was solved by optimizing the heterogeneous structures in the HSOT polymers. As a result, the HSOT polymer backlighting system with sufficient color uniformity was achieved. In addition, the HSOT polymer backlighting system is suitable for recent thin LCDs because of these advantages.

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