Special issue paper. Semiconductor lasers for optical communication

At the same time as interest in optical communication systems is rapidly accelerating, the field of semiconductor lasers is advancing on two main fronts: on one hand the existing devices are maturing rapidly, so that reliable c.w. lasers, capable of room-temperature operation and providing milliwatts of power which can be modulated at some hundreds of MHz, are on the verge of becoming commercially available and on the other hand many laboratories are actively seeking new junction structures and device configurations with the ultimate aims of substantial reductions in operating current, improved mode control and better life. In this paper we review some of the recent research which is leading towards the ideal laser for optical communications and discuss in detail the operating characteristics of present day lasers from the point of view of those parameters which are important in applying these devices in real systems.