Introduction

Abstract

Since the important formula of Shannon showing that, for an ideal band-limited Gaussian channel, the channel capacity is proportional to the channel bandwidth, many engineers have tried to take advantage of optics to develop optical communication systems. Because of the lack of high quality optical sources and detectors, practical users of optical communication systems have until recently made little progress. In the last few years, however, technological progress in the generation of laser light of high quality frequency accuracy and stability, as well as in the production of low loss optical fibers, has stimulated important research work in the design of systems for optical communication.