Study On The Influence Of Atmospheric Effects On The Performance Of Coherent Optical Communication Systems

With the higher receiver sensitivity, the coherent optical communication system has a competitive advantage in the high-speed and long-haul communication and is the development direction of the space optical communication. However the refractive-index fluctuations induced by the atmospheric turbulence will lead to the random variations of the amplitude and phase of the optical signal,it will reduce coherent detection efficiency and affect the performance of communication system. So there is an important significance to investigate the influence of the atmospheric turbulence on the space coherent optical communication.Hower, most of the former theory models of the space coherent optical communication system are based on the plane wave transmission model, but the plane wave model can’t study the influence of the beam radius on system performance. In addition, Optical coherence technology began in the direction of innovative development, balance detection is a typical representative.Based on balanced detection, this dissertation analyzes the influence of turbulence on the spatial coherent optical communication system performance, in the condition of plane wave model and Gauss beam model have been used in light field model of signal light and LO light.And obtained the SNR probability density function of the system and the error rate expressions.in the absence of turbulence and turbulent. On this basis,for the horizontal transmission coherent optical communication link, the influence of the scintillation index, the phase variance on the bit-error rate of the system is investigated, in the conditions of without phase compensation and adaptive phase compensation technology.The influence of aperture averaging on the optimum receiver aperture diameter is also investigated. For the satellite-to-ground coherent optical communication downlink, analysis the influence of aperture averaging and zenith angles on the bit-error rate of the system.Finally, experimental measurements the atmospheric channel attenuation coefficient in different weather conditions. As a reference to the experimental parameters, the coherent and non-coherent optical communication system performance is simulated under the conditions of different weather.