设计了由环形器、耦合器、衰减器和平衡探测器组成的平衡探测(BD)结构的OLCR系统, 分析了衰减直流分量产生的原因以及耦合器相位特性在BD结构中的作用。对参考臂中光耦合效率与反射镜角度和位置关系进行了仿真, 结果表明耦合效率主要受反射镜偏转角度影响。实验测试了非平衡和平衡结构下参考臂的输出光功率, 对噪声的均方根值和信噪比进行了分析, 同时还测试分析了两种结构下的干涉信号。实验结果表明, OLCR系统的BD结构在滤除衰减直流分量的同时还能抑制噪声信号和放大交流分量, 结构简单有效。

An OLCR system based on the BD structure was designed, which consists of the circulator, the coupler, the attenuator and the balanced detector. Also introduced was the cause of decaying DC component and the effect of coupler′ phase character in the BD structure. The relationship between the optical coupling efficiency and the angle and position of the mirror is simulated in the papaer and the result shows that the coupling efficiency is mainly influenced by the angle. The output light power of the reference arm in the unbalanced and balanced structure was measured with the root mean square value of noise and the S/N ratio analyzed. Further more, the interference signal between the unbalanced and balanced structures was also measured and analyzed. It is experimentally shown that the BD structure of the OLCR system can filter the decaying DC component,suppress the noise signal and amplify the AC component, while the structure working simply and effectively.