为了合理设置雪崩光电二极管(APD)探测器的偏压, 在恒定温度下实现倍增因子可调, 分析了APD探测器的工作原理及影响其探测灵敏度的因素, 并在室内对APD探测器的探测灵敏度进行测试。实验结果表明: 当通信速率为10~2000 Mb·s-1时, 探测灵敏度可达-47~-34 dBm; 当偏压为55.0~70.0 V时, 10,100,1000 Mb·s-1通信速率下的探测灵敏度分别提高了5.7,6.5,7.8 dB。实验结果很好地验证了理论分析的正确性, 这为空间激光通信系统接收性能的提高提供了技术支持。

In order to reasonably set the bias voltage of an avalanche photodiode (APD) detector and thus to achieve the adjustable multiplier factor at a constant temperature, we analyse the working principle of the APD detector and factors of influencing its detection sensitivity, and measure the detection sensitivity of the APD detector in laboratory. The experimental results show that the APD detection sensitivity ranges from -47 dBm to -34 dBm when the communication rate changes from 10 Mb·s-1 to 2000 Mb·s-1. When the bias voltage changes from 55.0 V to 70.0 V, the detection sensitivities at communication rates of 10,100,1000 Mb·s-1 increase by 5.7,6.5,7.8 dB, respectively. The experimental results well validate the theoretical analysis, which provides technical support for improving the receptivity of space laser communication system.