Laser frequency stability requirements for coherent space communications

The required laser frequency stability for a coherent optical receiver is analyzed for both data communication and Doppler tracking applications. A brief overview of the coherent receiver is provided. The application of phase coherent reception in data communication is addressed, and the required signal power level needed to achieve phase coherent reception is calculated based on the laser frequency noise model measured for the lightwave lasers. For data communications, it is the short-term stability of the lasers that is of primary concern. The issues related to the short-term frequency stability are addressed. The long-term frequency stability problem and its requirements in Doppler measurement are considered