Large-capacity optical communication systems

Along with widened and diversified social activities, there is an increasing demand for transmission capacity including voice, data, video and yet-to-evolve new entertainment markets. Studies are optical modulation/demodulation circuits and transmission characteristics of rare earth doped fiber amplifiers which satisfy the requirements needed in widening the repeater-span and increasing the transmission speed. It has become possible to realize ultrahigh-speed 10 Gbit/s transmission systems with the capacity of about 130,000 telephone channels. In these systems, besides the flexibility in their transmission bit rate and new forms of installation, maintenance and operation, it is considered that the new technology will contribute to a great evolution in future optical communication networks and equipment. A prospective on a next-generation large-capacity optical communication techniques also is given.