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Katsunari Okamoto |
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Katsunari Okamoto |
Katsunari Okamoto, is one of the four newly elected members of the LEOS Board of Governors. He is the head of Okamoto Research Laboratory at NTT Photonics Laboratories, Japan. The Photonics Laboratories within the NTT Holding Company focuses on research and development of photonic integrated circuits and optical components for optical communication systems.
Katsu Okamoto was born in Hiroshima, Japan in 1949 and grew up in the countryside of Hiroshima enjoying natural beauty and sports. After high school, he entered the University of Tokyo. He received the B. S., the M. S., and the Ph.D. degrees in Electronics Engineering from the University of Tokyo in 1972, 1974, and 1977, respectively.
During his postgraduate research at Tokyo University, he started theoretical investigations on the transmission characteristics of optical fibers under the direction of the late Prof. Takanori Okoshi. In the early 1970s, propagation characteristics of graded-index fibers were not fully understood. In those days WKB and staircase concatenation methods were used for the analysis of fibers. WKB method is suitable for the analysis of multimode fibers but is not suitable for single-mode fibers. The staircase concatenation method divides graded-index profile into multiple layers and approximates with the staircase function. Therefore, it is rather difficult to obtain good numerical accuracy with a practical number of segments. Katsu noticed a versatile applicability of variational method combined with Rayleigh-Ritz method or finite element method (FEM) in analyzing graded-index fibers. He clarified the cutoff conditions of fibers of arbitrary refractive-index profiles and calculated dispersion characteristics for fibers with various index profiles. He extended this technique to synthesize the optimum refractive-index profile of the multimode fiber that minimizes multimode dispersion.
After graduating from the University of Tokyo, he joined Ibaraki Electrical Communication Laboratory, NTT in 1977. There he started research on transmission characteristics of single-mode fibers. He proposed for the first time the dispersion-flattened fiber (DFF) which has a W-type index profile. After his theoretical prediction, researchers in his group succeeded in fabrication of DFF that had chromatic dispersion less than ´1 ps/km/nm over a wide spectral range.
He then shifted his research focus to polarization-maintaining (PANDA) fibers and fiber-optic components. He calculated the optimum stress-applying structure for PANDA fibers by using FEM stress analysis. His group fabricated PANDA fibers with crosstalk less than –42 dB at 1 km. He also fabricated an all-PANDA-fiber gyroscope using a PANDA fiber coil as a rotation sensing head, polarization-maintaining 3-dB couplers and fiber polarizers. Katsu’s group obtained the minimum rotation sensitivity of 0.01 deg/hr.
From September 1982 to September 1983, he joined Optical Fiber Laboratory headed by Prof. W. A. Gambling at Southampton University, Southampton, England as a guest researcher. He worked with Dr. D. N. Payne on the research of birefringent (Bow-tie) optical fibers and fiber polarizers. He and his family loved Southampton very much and enjoyed visiting various parts of UK.
From October 1987 to October 1988, he stayed at RCAST (Research Center for Advanced Science & Technology) of University of Tokyo as Associate Professor with Prof. E. A. J. Marcatili from AT&T Bell Laboratories. Henry Marcatili was invited as a guest professor of the endowed chair at RCAST. Henry and Katsu studied the influence of nonlinear optical effects on propagation characteristics of optical fibers. They taught electromagnetic theory, optoelectronics and fiber optics at Electronics and Applied Physics Department.
Since 1990, he has been working on the analysis and the synthesis of guided-wave devices, the computer-aided-design (CAD) and fabrication of silica-based planar lightwave circuits (PLCs) at Ibaraki R&D Center, NTT Photonics Laboratories. He developed a CAD tool based on the beam propagation method and a FEM waveguide and stress analyses. The design tool for arrayed-waveguide grating (AWG) filter is widely utilized in Photonics Laboratories and its subsidiary companies. He has developed a 256×256 star coupler, various kinds of AWGs ranging from 8ch-50nm spacing AWGs to 128ch-25GHz AWGs, flat spectral response AWGs and integrated-optic reconfigurable add/drop multiplexers. 200 GHz to 50 GHz spacing AWGs are now widely used in the commercial WDM systems.
In 1997, he was appointed Head of Okamoto Research Laboratory. His group aims at development of highly functional waveguide devices for next generation photonic networks.
Dr. Okamoto has published more than 160 papers in technical journals and international conferences. He authored and co-authored 8 books. One of them was recently published by Academic Press under the title of “Fundamentals of Optical Waveguides”. He served as LEOS Distinguished Lecturer (’97-’98). He also served as one of the Topical Editors for IEEE Journal of Selected Topics in Quantum Electronics (’96 and ’99). He served several technical program committees such as the LEOS Annual Meeting, Optoelectronics and Communications Conference (OECC) and the Conference on Optical Fiber Sensors (OFS). He is currently an International Liaison of OFC for Asia/Pacific Rim region (’98~). In addition to his LEOS membership he is a member of Optical Society of America, the Institute of Electronics, Information and Communication Engineers of Japan and the Japan Society of Applied Physics.
Katsu and his wife Kuniko live in Mito-city, Ibaraki-prefecture, with their sons Hiroaki and Masaaki. Katsu’s favorite sports are cycling and badminton. Almost everyday, he enjoys playing badminton with his colleagues.