中文摘要：

星地空间相干光通信中，受大气湍流及空间光耦合效率因素的影响，要实现高速率、高探测灵敏度的通信变得异常困难。针对星地空间相干光通信链路中空间光耦合较难的问题，提出了采用大面积平衡探测器来提高探测灵敏度的方法。通过分析平衡探测技术的原理及平衡探测器结构，设计了一种探测面直径为100 μm、工作速率为5 Gbps的平衡探测器，搭建了空间相干光通信测试平台。在5 Gbps通信速率下，探测器的直接探测灵敏度达到-18.6 dBm，相干探测灵敏度达到-43.89 dBm，共模抑制比高于38.5 dB。测试结果验证了该空间光耦合平衡探测器用于空间相干光通信的可行性。

英文摘要：

Affected by the factor of atmospheric turbulence and spatial optical coupling efficiency in the satellite-ground coherent optical, it′s extraordinarily difficult to achieve high data rate and high detection sensitivity of communication. In view of the difficulty of spatial optical coupling in the satellite-ground coherent optical communication link, the method to improve the detection sensitivity by using large area balance detector was proposed. Based on the analysis of the balance detection technology′s principle and structure, the balance detector with a diameter of 100 μm and a working speed of 5 Gbps was designed, and the simulation test platform of the spatial coherent optical communication was built. Under the communication rate of 5 Gbps, the direct detection sensitivity of the detector is -18.6 dBm, the coherent detection sensitivity is -43.89 dBm, and the common mode rejection ratio is above 38.5 dB. The test results verify the feasibility of the spatial coupling balance detector for coherent optical communication.