Research on tunable local laser used in ground-to-satellite coherent laser communication

In order to realize homodyne reception and Doppler frequency shift tracking in ground-to-satellite coherent laser communication, a local laser is experimentally demonstrated in this Letter. It is realized based on modulation-sideband injection locking, and has a 10 GHz tuning range, a 1 THz/s tuning rate, a 5 kHz linewidth, and 16 mW of output power. When applied to a Costas loop in a coherent laser communication system, the local laser can achieve ±5 GHz Doppler frequency shift tracking with a 20 MHz/s frequency shift rate, which is sufficient for the ground-to-satellite coherent laser communication.