Fast phase locking method for homodyne laser communication based on direct phase control

Abstract

In the field of space optical communication, coherent communication system has the advantages of high sensitivity, compatibility with a variety of modulation formats and strong anti-interference ability compared with intensity modulation direct detection (IM-DD) system. The typical disadvantage of coherent communication system is the complexity of the receiver, which requires carrier recovery. Space optical communication is also developing from point-to-point communication to optical communication network. In this paper, a fast phase locking method based on direct phase control is proposed. After the auxiliary frequency acquisition is completed, the time to recover the carrier is equal to the loop delay. The realization of this method depends on the direct control of the local oscillator carrier phase. Different from the traditional second-order loop method, this method does not need to consider the laser linewidth. This method can greatly save the time of carrier recovery, so it can be used for fast switching of optical network channels and can improve the utilization of optical networks.