Resesrch On High Sensitivity Heterodyne Coherent Detection Technology Of Space Optical Communication

Space laser communication plays an important role in high-speed, high sensitivity, and long-distance transmission aspects.It is a hotspot in the fi eld of com munications. It can improve the sensitivity of the system by using heterodyne detection.On this basis of its higher sensivity,thi s paper carryed out research on heterodyne coherent detection systems, mainly for electrical phase-locked loop system.At first this paper introduced the prin ciple of direct de tection, homodyne and heterodyne detection respectly.T he comparison of these m ethods' disadvantages and advantage were displayed in the next. Then,this paper introduced the detection m ethod of heterodyne in details. Analysis three main parts of heterodyne detection, and on the base of the analysis this paper take Costas loop to demodulate the IF signal.This paper focused on the influence of the various parts of heterodyne detection system.And then design the optimal heterodyne detection system based on Costas loop. The design parameters of the system are: signal light wavelength is 1550 nm, optical power is 1mW, the wavelength of LO is 1550.084 nm, the optical power of Lo is80 m W, the rate of the communication is 5Gb / s, the maximum value of Q is 6.