研究者情報 | Keio Research Showcase

Introduction

Yasuhiro Koike is internationally recognized as the inventor of graded index plastic optical fiber (GI-POF), which enables high-speed optical communication. His research focuses on discovering novel functions, such as GI-POF, birefringence controlled films, etc. by investigating the interactions between polymer structures and optical fuctionalities tracing back to their fundamentals origins. In GI-POF research, his research team has successfully developed a technology to fabricate multi-core GI-POF in a single step using the extrusion process, enabling ultra-high-speed transmission of over 100 Gbps per core. The team has also successfully developed an ultra-fine disposable endoscope utilizing GI-POF as optical lens for medical application. In research on birefringence controlled films, his team has been developing random depolarization films that enable real-color displays by converting the linearly polarized light into randomly polarized light, with the aim of early social implementation, in collaboration with industry, government and academia. He has been awarded Society of Plastic Engineers (SPE), International Technology Award -Fred O. Conley-, The Fujihara Award, Takayanagi Memorial Award, “Shiju Housho”, Medal with Purple Ribbon awarded by Emperor of Japan, Society for Information Display (SID) Special Recognition Award, The Society for Polymer Science, Japan (SPSJ) Award for Outstanding Achievement in Polymer Science and Technology, etc.

Achievements

1. Y. Koike, Y. Sumi, and Y. Ohtsuka, “Spherical Gradient-Index Sphere Lens,” Applied Optics, Vol. 25, No. 19, pp. 3356-3363, October, 1986.
2. Y. Koike, “High-Bandwidth Grade-Index Polymer Optical Fiber,” Polymer, Vol. 32, No.10, pp. 1737-1745, June, 1991.
3. Y. Koike, S. Matsuoka, and H. E. Bair, “Origin of Excess Light Scattering in Poly (Methyl Methacrylate) Glasses,” Macromolecules, Vol. 25, No. 18, pp. 4807-4815, September, 1992.
4. A. Tagaya, H. Ohkita, M. Mukoh, R. Sakaguchi, and Y. Koike, “Compensation of the Birefringence of a Polymer by a Birefringent Crystal,” Science, Vol. 301, Issue 5634, pp. 812-814, August, 2003.
5. Y. Koike, and M. Asai, “The future of Plastic Optical Fiber,” NPG Asia Materials Vol. 1(1), pp.22-28, 2009.
6. Y. Koike and K. Koike, “Progress in Low-Loss and High-Bandwidth Plastic Optical Fibers,” Journal of Polymer Science Part B: Polymer Physics, Volume 49, Issue 1, pp. 2-17, 2011.
7. Y. Koike and A. Inoue, “High-Speed Graded-Index Plastic Optical Fibers and their Simple Interconnects for 4K/8K Video Transmission,” Journal of Lightwave Technology, Invited paper, Vol. 34, No. 6, pp.1551-1555, 2016.
8. A. Inoue and Y. Koike, "Low-Noise Graded-Index Plastic Optical Fiber for Significantly Stable and Robust Data Transmission," Journal of Lightwave Technology, Vol. 36, No. 24, 5887-5892, 2018.
9. K. Watanabe, Y. Kobayashi, and Y. Koike, "Proposal of Novel Temperature-Independent Zero-Zero-Birefringence Polymer with High Heat-Resistance," (Invited Paper for Special Section on Electronic Displays), IEICE Trans. Electron., Volume E104-C No.2, Feb., 2021.
10. T. Akashi, A. Inoue, and Y. Koike, "Low-Noise Graded-Index Plastic Optical Fiber Achieved by Specific Copolymerization Process," Journal of Lightwave Technology, Vol. 39, Issue 11, June, 2021.
11. S. Sasaki and Y. Koike, "Randomizing polarization of displays for fundamental improvement of color mura caused by birefringence," Optics Letters, Vol. 49, Issue 22, pp. 6501-6504, Nov, 2024.
https://doi.org/10.1364/OL.544097
12. Y. Koike and K. Muramoto, "Error-free PAM-4 transmission by a high-speed plastic optical fiber without forward error correction," Optics Letters, Vol. 46, No. 15, August 2021.
13. K. Muramoto and Y. Koike, "Stabilized Plastic Optical Fiber Link Even Without a Physical-Contact Fiber Connection," Journal of Lightwave Technology, Vol. 42, Issue 2, pp. 875-881, January, 2024.

Areas of Research

・High-Speed Plastic Optical fiber and communication systems
・Real-Color Displays
・Optical lenses

Social Contributions

・Realization of high-capacity, low-power and low-latency data communications for beyond 5G (6G) era
・Realization of high-definition real-color display by birefringence controlled films
・Advances in environmental and industrial applications