空间相干光通信中平衡探测器灵敏度测试实验

在空间相干光通信中,为了对本振激光器和大气信道产生的共模噪声进行有效的抑制,接收机中广泛引入平衡探测器,通过分析可知,平衡探测器在相干探测时灵敏度明显提高。为了探求空间相干通信中平衡探测器的性能,对其噪声形成的机理进行了分析,给出了2.5 Gbps和5 Gbps平衡探测器在非相干与相干探测条件下的灵敏度理论极限。设计了2.5 Gbps和5 Gbps平衡探测器,构建了平衡探测器测试系统,并对其灵敏度进行了测试,在2.5 Gbps通信速率下,非相干探测灵明度达到-21.1 dBm,相干探测的灵敏度达到-41.2 dBm,测试结果与理论分析值基本吻合。空间相干光通信中平衡探测器分析与设计为空间相干光通信系统提供了理论依据和实现条件。

Sensitivity testing and experiment of balanced photodetectors in the space coherent optical communication

Balanced photodetectors can suppress effectively common-mode noise produced by laser and atmospheric channel in the space coherence optical communication. The sensitivity of balanced detectors are obviously improved in the coherent detection. In order to explore the performance of balanced detector, noise mechanism of balanced photodetector was analyzed. The 2.5 Gbps and 5 Gbps theoretical limit of sensitivity was presented in the condition of incoherent and coherent detection. Balanced photodetectors were designed and test system was built for the mesaurement of sensitivity. In 2.5 Gbps communication rate, incoherent detection sensitivity reached -21.1 dBm, and coherent detection sensitivity reached -41.2 dBm. Test results roughly coincide with theoretical analysis. The reason that test results deviates from the theoretical value was analyzed. Sensitivity analysis and design of balanced photodetectors provide a theoretical basis for the realization of the space coherent optical communication system.