Effect of Doppler shift on differential phase-shift keying receivers using interferometric demodulation and balanced detection in intersatellite laser communication links

Doppler shift due to relative movement between satellites must be taken into consideration in intersatellite laser links. The degradation of differential phase-shift keying (DPSK) receiver performance caused by Doppler shift is assessed. In order to simplify the complexity of the receiver, we discuss conditions that will bring the new design concept for a robust laser communication system in space, which does not require precise active control. When the precise active control has to be used, the impact of frequency drifts relative to optical filter's center frequency becomes evident. Optimum bandwidths of optical filters yielding optimum performance over the entire range of frequency shifts are determined to further improve the receiver performance. The results obtained here will be helpful in the design of DPSK/self-homodying intersatellite laser communication systems.