|Budget Amount *help
¥7,200,000 (Direct Cost : ¥7,200,000)
Fiscal Year 1995 : ¥1,600,000 (Direct Cost : ¥1,600,000)
Fiscal Year 1994 : ¥5,600,000 (Direct Cost : ¥5,600,000)
In an optical amplifier chain, transmission distance beyond 1,000km is attained without using regenerating rapeaters, because optical loss in fibers is periodically compensated. However, in such a system, the optical power is maintained at a high level along the entire system length and hence the Kerr nonlinearity of optical fibers can no longer be ignored. The Kerr nonlinearity, in turn, interplys with the group velocity dispersion of fibers, causing serious waveform distortion. To cope with this problem, we propose an optical transmission system using midway optical phase conjugtion, and investigate the feasibility of the system. The main results obtained in this research project are shown in the following.
(1) We found that the insufficient efficiency of waveform distortion compensation was mainly caused by the sideband modulation instability originated from the periodic optical power distribution, and obtained the design rule of the system to maximize the efficiency by reducing the effiect of sideband modulation instability.
(2) The optical phase conjugator using dispersion shifted optical fibers was designed. We achieved the conversion efficiency of several percent by the device fabricated according to the design.
(3) The optical phase conjugator using semiconductor optical amplifiers was demonstrated. When the pump-probe detuning was 200GHz, the conversion efficiency larger than OdB was achieved. The introduction of this device into the transmission system was effective for eliminating the four wave mixing generated in optical fibers.