Simulation Analyses Of Influences Of Atmospheric Turbulence For Receiving Performance Of The Laser Coherent Communication System

Satellite laser communication system has many advantages, such as high data rate, low intercepted probability, strong ability of anti-interference, less volume, less consumption of power and so on. Currently, satellite laser communication has turned to be a hot international research field. Space experiments which includes intersatellite and ground-to-satellite laser communication experiments have been realised in Japan, American and Europe. In the near future, this technology will be promoted to real utility. In free space optical communication, coherent optical communication which has many advantages of higher sensitivity and longer distance relay has been a hot research field, also become a good choice for space laser communication in the future.In ground-to-satellite coherent optical communications, laser beam, as the carrier of information, will propagates through the atmosphere. In this process, the coherence of the optical field will be destroyed by atmospheric turbulence and it will cause a series of optical effects, such as beam wander, beam spread and intensity fluctuation, etc. These effects will affect the performance of ground-to-satellite laser communication. Therefore, the study of atmospheric turbulence effects on laser communication system is necessary.Owing to optical field of ground-to-satellite laser communication uplinks and downlinks propagating through atmosphere and free space in a different order, the optical effects are also not the same. So separate analysis of atmospheric turbulence effects of the uplink and downlink is necessary. And with consideration of the atmospheric turbulence effects, the performance of the ground-to-satellite coherent optical communication downlink is analysed in this paper.Firstly, the research situation of coherent optical communication and ground-to-satellite laser communication is summarized. Then, the properties of the atmospheric turbulence is described. Influences of turbulence effects on the system and basic theory of laser propagation in atmospheric turbulence are represented. The system situation and principle of the coherent optical communication system are introduced, and the heterodyne efficiency and BER of ground-to-satellite coherent optical communication downlink are theoretically studied.In this paper, the heterodyne efficiency and BER of ground-to-satellite coherent optical communication downlink are numerically studied by the atmospheric multi-layer random phase screen model. And with use of adaptive optics system, this paper is concerned with the research on the compensation of the effects of turbulence.