Research On Influence Of Atmospheric Turbence To Satellite-Ground Downlink Laser Communication Systems Based On Single-Mode Fiber Coupling Recieved

In order to satisfy the larger capability and higher rate of information transmission , free-space communications is important method. Some developed countries have successfully equipped with the satellite optical communication terminal on the satellite and done the satellite-to-ground and intersatellite laser communication experiment.Satellite - ground laser communication is connection of inter-satellite optical network and terrestrial fiber optical network,which contains uplink and downlink. A large of information collectted by satellite need to transsmited to earth-station efficiently,so research on satellite-ground communication downlink have applicated meaning. In satellite-ground laser communication, atmosphere is a part of transsimition channel,in which laser was inevitably interfered by atmospheric turbulence when propagated through the atmosphere, the random fluctuation of the refractive index caused by the atmospheric turbulence will decline the coherence of laser signals, and then affect the receiver performance. The technology of satellite communication that wavelength is 1550nm have widely used in high rate of laser communication, in which technology of spacial laser couplled into single mode fiber is a key.So this paper research on influence of atmospheric turbulence to satellite–ground downlink laser communication system based on single mode fiber coupling received.This paper have done the theoretical analysis to single-mode fiber coupling efficiency for received and obtained the analytical expression of single-mode fiber coupling efficiency when existed random point dias,and then analyzed influence of angle of arrival to single-mode fiber coupling efficiency in satellite-to-ground laser communication downlink.Based on analysis of the bit error rate in satellite-to-ground laser communication system, this paper researched on performance of laser communication systems which was based on single-mode fiber coupling affected by atmospheric turbulence.This paper also analysed the effect of the residual wavefront distortion caused by atmospheric turbulence on single-mode fiber coupling efficiency, single-mode fiber is a weighted aperture,which excisted the terms of the cross-coupling. Take an example of the term of x-direction tilt corrected,in oerder to analysis the diffierence between residual phase distortion existed the terms of the cross-coupling and original residual phase distortion.