Coherent optical system for inter-satellite communications

Concentrate on heterodyne detection at 1.5 μm (wavelength) using semiconductor lasers. A coherent system breadboard has been realised and tested to demonstrate and assess the capability of this technology for optical intersatellite links. A sensitivity of -46.5 dB has been achieved which is 11.4 dB from the shot noise limit. The system penalties have been evaluated and used to derive a link budget for a geo-geo link which indicates that a transmitter power of approximately 43 mW is required. The potential for optical fibre within the receiving satellite has been studied and appears very attractive in that the theoretical insertion loss is less than 1 dB (and is identical to the mixing loss in the Airy-Gaussian case) and there is great potential for reducing the mass, volume and complexity especially in the stabilized platform