Optical fiber transmission system research for public telecommunication in Japan

Abstract

Abstract Since the early 1960's, much theoretical and experimental research has been done in optical transmission system research in Japan. This effort has been greatly stimulated by the prospect that the optical system would provide versatile transmission systems for an extended applicable area from small to large capacity, both in trunk and in local routes in Japan. Since 1974, transmission experiments on the repeatered line have been conducted repeatedly by several laboratories in the industry and by the Electrical Communication Laboratories, at 32, 100, 400, and 800 Mb/sec. A medium-capacity system with 32–100 Mb/sec would probably be the earliest practical system in Japan. During the past six years, losses of the optical fibers have decreased remarkably, and have attained 0.5 dB/km in a bare fiber at a 1.2-μm wavelength. [1] Novel techniques for epitaxial growth and processing have improved the semiconductor laser lifetime and yield. This paper presents an overall view of recent progress in optical s...