Analysis Of Mixing Efficiency In Satellite To Ground Coherent Laser Communication System

The free space coherent laser communication has the advantages of large communication capacity, high sensitivity, long distance and multi-modulation format, which is considered to be a promising method for communication. In the coherent laser communication, the optical mixer is an important device of the coherent mixing, and the fundamental condition of the signal light and the coherent mixing. In this paper, the main factors affecting the optical mixer in coherent laser communication, like vibration, mode matching, polarization and wavefront distortion are well theoretical analysis studied and experimental analyzed.In this paper, it analyzes the important guarantee of the 90 ? mixer, that is, the optical phase lock loop. And then the theoretical basis of the optical mixer is drawn up, and the theoretical feasibility of the mixer is demonstrated. And then it carries out the analysis of the influencing factors. The effect of vibration on the mixing efficiency is analyzed, and then is the influence of the vibration on the coupling efficiency, after that is the influence of the vibration on the coherence efficiency. The two factors are combined as the influence of the vibration on the mixing efficiency. The effect of pattern matching on mixing efficiency is analyzed, and the mixing efficiency to the modes signal light and the local oscillator is theoretically deduced and experimentally verified. And then, theoretical modeling of the influence of polarization state on mixing efficiency is made, and the influence of polarization state on the mixing efficiency is analyzed and experimentally verified. At last, theoretical modeling and analysis of the influence of wave front distortion caused by atmospheric disturbance on the mixing efficiency is made.