研究了4 路偏振切换技术在光纤干涉仪中的应用，建立了基于4 路偏振切换的抗偏振衰落的理论模型，运用了复数运算的方法解决4 路信号的合成问题，对偏振诱导信号衰落的抑制效果进行了仿真。偏振衰落实验搭建了基于非平衡的迈克尔孙干涉仪的实验系统，采用相位产生载波技术(PGC)外调制方案解调信号，对4 路偏振切换技术抗偏振衰落效果进行了实验测试。结果表明，4 路干涉信号合成后，可以消除传输光纤双折射的影响，合成干涉信号的解调结果与单路解调结果一致；合成干涉信号的等效干涉度可以稳定在0.838，验证了偏振切换技术抗偏振衰落的有效性。

The basic principle of polarization switching to eliminate polarization- induced fading in fiber optic interferometers is studied. A theoretical model is constructed and the complex method of complex is introduced to solve the problem that four signals compose one signal. Theoretical analysis and simulation show that polarization switching can eliminate polarization-induced fading. An experimental system based on non-balanced Michelson interferometer is built. Using phase generation carrier (PGC) modulation technology to demodulate signal, the antipolarization effect of the four-way polarization switching is tested by experiment. The results show that the birefrigent effect of the lead fiber can be eliminated after the signal is composed. After four signals compose one signal in the experiment, its visibility can be a stable level of 0.838. The result keeps with the visibility of Michelson interferometer under ideal condition, which proves the feasibility of polarization switching in elimination of polarization-induced fading.