中文摘要：

为研究空间相干光通信的信噪比受本振光功率、探测器特性和光波偏振态的影响，对探测器在不同工作状态下以及光波偏振态变化时的信噪比进行了研究，讨论了在不同工作状态下探测器特性参数和本振光功率对信噪比的影响，并通过实验验证了本振光功率和光波偏振态对信噪比的影响。结果证明空间相干光通信中探测器特性参数限制了本振光功率的取值，实际最大信噪比小于理论值，最佳本振光功率大于理论值，且两光束的偏振方向越接近，输出信噪比越大，最佳本振光功率越小。

英文摘要：

To study the effect of local oscillator power, detector characteristics and polarization on signal- to-noise ratio （SNR） of the space coherent optical communication, the SNR were studied under different working conditions. The effect of characteristic parameters of the detector under different work status and the local oscillator power on the SNR was discussed. The effects on SNR was verified through the experiment. Results show that the characteristic parameters of the detector limit the value of the local oscillator power. Actually, the maximum SNR is less than the theoretical value in coherent optical communication, the optimum value of local oscillator power is greater than the theoretical value, and the closer the two polarization direction of the light beam, the greater the output SNR, the smaller the optimum value of local oscillator power.