Research Of Homodyne Detection Technology In The System Of Coherent Space Laser Communication

Due to the advantages of its high code rate,narrow bandwidth,high receiving sensitivity, people are more and more concerned about the technology of free space coherent optical communications.Based on the principle of coherent detection, key technology and main devices related to coherent optical communication system were analyzed in this paper, especially, optical phase lock loop (OPLL), the core part of the coherent receiver, was thoroughly analyzed and discussed. By establishing mathematical model,we have achieved relational expression of optimal bandwidth and minimum noise variance of coherent optical communication system based on COSTAS OPLL. At the same time, the optimization of the natural frequency has been realized; The relationship between laser line-width and error rate were analyzed and the emergence of background error rate was discussed; we also analyzed the stability of the system. Finally, the design of coherent optical communication system has initially been established, based on this, the main parameters of coherent optical communication system were calculated and simulated.