Design and system requirements imposed by the selection of GaAs/GaAlAs single mode laser diodes for free space optical communications

The GaAs/GaAlAs single mode laser diode has unique properties and capabilities which make it attractive for an optical communication system. The attractive features are related to its small size, semiconductor structure, ease of optical control, wavelength sensitivity and system simplicity. The diode possesses other less well known and less appreciated properties which include limited power capability, thermal and environmental sensitivity and susceptibility to static charge damage. It also has unproven reliability when operated pulsed in a digital communication system. The operating features of the diode impose restrictions on the design of the system and generate additional system requirements for the development and use of the system. The properties of the single mode laser diode are discussed and the additional system design features and system requirements identified.