The Costas loop is the key technique of synchronous demodulation in the next generation of satellite optical communication systems. To better understand the Costas loop, the relationship between phase deviation of the Costas loop and bit error rate (BER) performance of a binary-phase-shift keying (BPSK) space uplink optical communication system is achieved.
Furthermore, the BER performance versus frequency deviation, zenith angle, data rate, and divergence angle are analyzed. Simulation results indicate that BER performances are not sensitive for parameters when the phase deviation of the Costas loop is designed with restriction of $pi/16$. These results are helpful for enhancing BER performance and the design of space optical communication systems.