Towards a coherent optical free-space communication system

A coherent optical communication system based on a diode laser pumped Nd:YAG laser with 620 mW single frequency output power has been developed. Differential phase shift keying at a data rate of 565 Mbit/s has been applied. Bit-error-rates of 10/sup -9/ have been measured at a received light power of -46 dBm.