Infra-red optical communication systems∗

Abstract

This paper presents a survey of the present position of the technology of optical communication systems. The gallium arsenide laser and gas lasers are compared as sources. The Pockel effect, acoustic and Faraday effect modulators are discussed. The advantages and disadvantages of various transmission systems are also discussed. Brief comments are made about various types of detectors. It is concluded that the information capacity is limited by the bandwidth of the source, modulator or detector. No satisfactory transmission system for long distance telecommunications use has yet been perfected, but guided systems of the type illustrated by a dielectric fibre guide, seem to offer the most promise. Despite the advances made in sources and modulators, many problems still remain before optical frequencies can be used for long distance telecommunication systems. Short range and outer space systems are feasible with the existing techniques.