为了减小大气湍流引起的星地激光通信系统的性能衰落,采用基于光纤相干合束的多孔径接收方案。针对典型的星地相干激光通信模型,给出了通信系统的灵敏度和误码率随多孔径接收对湍流效应的补偿效果变化的数值仿真结果。同时基于已有的光纤合束方法搭建了一套4孔径接收的相干合束光通信接收装置,测试了2个和4个孔径下系统的锁相带宽。利用旋转相位屏模拟了不同Greenwood频率的大气湍流对光束波前的影响,保证了各路接收光强的不相干性。在此基础上,给出了相干合束前后光纤中的光强相对起伏方差。结果表明该系统能在弱湍流环境中有效地抑制光强闪烁。

In order to mitigate the performance fading of satellite-to-ground laser communication system caused by atmospheric turbulence, a multi-aperture receiving scheme based on fiber coherent beam combining (CBC) is used. A typical satellite-to-ground coherent laser communication model is considered in this paper, and the numerical simulation results of the variations in sensitivity and bit error rate of the communication system with turbulence compensation effect are given. Based on an existing beam combining method, a set of CBC optical communication receiver with four apertures is constructed, and the phase-locked bandwidth of the system under two and four apertures are measured. Then we use the rotating phase screen to simulate the influence of atmospheric turbulence on the wavefront at different Greenwood frequencies. Meanwhile, we ensure the incoherence of the received light intensity. On this basis, the relative fluctuation variances of light intensity in optical fiber before and after CBC are given. The results show that the system can effectively mitigate intensity scintillation in the weak turbulence.