偏振控制器（PC）是实现偏振控制算法的重要器件，也是量子密钥分发系统中的重要组成部分。提出了一种利用挤压器的相位与偏振态轨迹的旋转轴之间的关系来分析挤压型偏振控制器“极地盲区”问题的新方法。从理论上分析了此类偏振控制器的控制原理，推导出挤压器上相位变化与它的偏振态轨迹旋转轴之间相互影响的规律。基于以上特性，进一步分析了两个光纤挤压器级联的偏振控制器的“极地盲区”现象，即只有在极个别的输入偏振态才能实现任意偏振态输出，绝大多数的输入偏振态都有不能到达的区域。通过仿真和实验结果对比验证了理论分析的正确性，提出的一种规避盲区的偏振控制算法设计思路，可减少偏振控制的可变自由度。

Polarization controller (PC) is an important device for the automatic polarization control algorithm, which is also an important part in the quantum key distribution system. A new method of analyzing the polar blind zone of the fiber squeezer polarization controller is presented based on the relation between the phase of the fiber squeezer and the rotation axis of the polarization state trajectory. The control principle is analyzed theoretically, and the interaction law between the changed phase and the rotation axis of the state of polarization′s trajectory is deduced. Based on the above results, the “polar blind zone” phenomenon of the two fiber squeezers cascade polarization controller is further expounded, namely only in the extremely individual input polarization state, arbitrary polarization states can be output. The vast majority of the input polarization states cannot arrive certain areas in the Poincare sphere. The accuracy of theoretical analysis is verified through comparing simulation results and experimental results. An idea of the polarization control algorithm based on avoiding blind area is proposed, which can reduce variable degrees of freedom.