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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 part of the polarization control algorithm and an important part of the quantum key distribution system. A new method of analyzing the problem of squeezed polarization controller “Polar dead zone ” is proposed based on the relationship between the phase of the extruder and the rotation axis of the trajectory of polarization. The control principle of such a polarization controller is theoretically analyzed, and the law of interaction between the phase change on the extruder and the rotation axis of its polarization state trajectory is deduced. Based on the above characteristics, we further analyze the phenomenon of “polar blind spot” of the polarization controller cascaded by two optical fiber extruders, that is, the output of any polarization state can be achieved only in a very few input polarization states. Most of the input polarization There are areas that can not be reached. The correctness of the theoretical analysis is verified through the comparison between simulation and experimental results. A design idea of polarization control algorithm to avoid blind spots is proposed, which can reduce the variable degree of freedom of polarization control.