Fibre optic technology is now being exploited in many diverse applications including long haul and local network communications, using both direct detection and coherent techniques, sensor systems, microwave optical links and for signal processing. These applications demand active optoelectronic terminal devices such as sources, detectors and integrated components with performance parameters suitable for the application as well as costs (or cost projections) low enough to catalyse the development of the systems. Single frequency distributed feedback (DFB) lasers are now becoming widely available and are suitable for high speed (>2Gb/s) direct detection and for FSK cohefent systems. DFB lasers in combination with external or integrated passive cavities offer reduced linewidth and rapid electronic tuning, opening the way to multichannel subscriber networks. Optoelectronic components capable of microwave bandwidths (10-30 GHz) are also being reported; such components will find applications in microwave bandwidth point to point links, radar remoting and optical signal processing. Critical components here include the laser source, which may be directly modulated or followed by a high speed guided wave modulator and the detector/receiver. In this presentation developments in such active components for single mode fibre systems were reviewed.