Site: Osaka University
Department of Electrical Engineering Osaka, Japan
Date Visited: November 15, 1994
Report Author: F. Leonberger
Within the Electrical Engineering Department at Osaka University, two research groups have been very active and productive in guided wave optics for over 10 years: the Nishihara group and the group formerly headed by Professor Sueta, who retired, and now headed by Professor Izutsu. Professor M. Haruna, a long-time member of the Nishihara group, has recently moved to the medical faculty, where he will concentrate on applications of optoelectronics in medicine. Each group has about 15 members, typically consisting of 7 to 10 MS students and one PhD student. A group will graduate at most one PhD/year. The research funding is limited, typically consisting of a modest grant from the university, about $200 thousand/year from funded proposals (greater than average for a university), and some funding from consortia and industry (sometimes in the form of visiting engineers). The groups have had limited funding for equipment. They described a restructuring of the university to emphasize graduate education, and funding by the government for more equipment. Over the years, most students have gone to industry after completing the Master's degree course of study, and over 50% are employed in optoelectronics.
Several of the JTEC panel's hosts described aspects of the work in Professor Nishihara's laboratory. Professor Suhara described the history of the guided-wave optical CD pickup device as an example of a long-term project with industrial interest and support. This device includes a hybrid-integrated laser and a monolithically integrated Si/SiO 2 waveguide grating lens for projection/collection of light and photodetectors. While good results were obtained, the progress in conventional pickups obviated the commercial need for this device. However, effort is continuing in building a modified version of the device for position sensing and for examining advanced pickup designs, such as for super resolution. A key capability of the group is specialized e-beam writing of the grating lens. Dr. Ura further described the two-dimensional displacement sensor.
Professor Haruna described the LiNbO 3 activity. This included a discussion of an integrated laser-Doppler velocimeter, Nd-doped material and lasers, and the development by industry of his laser-writing lithographic system. He summarized his view of LiNbO 3 applications in Japan for communication (high-speed modulation), sensing (fiber gyros, switches for OTDRs), and memory (QPM frequency doubling). Dr. Fujimura further described the second harmonic generation work.
Professor Izutsu has a focus on four areas. These are nonlinear optics (bistable and all-optical devices), new waveguides for optical interconnects, ultrafast guided wave modulators (goal of 100 GHz), and LiNbO 3 integrated optic (IO) modulators for microwave systems. A particularly interesting activity is building prototype IO circuits for scanning antennas (phased arrays) envisioned for use in mobile phone systems. Phase and frequency shifting at 800 MHz are accomplished monolithically in a novel circuit.
The groups continue to do excellent work in integrated optics. However, they have concerns about the breadth of utilization of integrated optics due to alternate techniques (photonic or nonphotonic) to solve a given system problem.
The Osaka groups echoed themes the JTEC team heard elsewhere about the limited funding and equipment available for university research, the relatively few students that stay on for PhD-level research, and the small amount of collaborative work with industry. The preponderance of students going to industry after obtaining a Master's degree is a reflection not only of the funding, but also of the very small salary premium Japanese companies seem to place on the PhD. The companies seem to prefer to train MS students and place some of them in management tracks rather than hire a great many university-trained technical specialists.