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理论分析了偏振模式耦合的原理,给出了基于白光干涉的偏振耦合检测方法。通过步进电机控制迈克耳孙干涉仪扫描臂的反射镜移动,改变干涉仪两臂之间的光程差(OPD),补偿了由于偏振耦合而形成的两偏振光从保偏光纤(PMF)出射时的光程差,实现了对保偏光纤的偏振耦合强度和位置的测试。扫描过程中扫描臂反射镜的振动会对输出信号产生不良影响,对此振动信号进行了仿真及实验研究,分析了它对输出信号的影响。在不同的扫描速度下,采用Hilbert变换和最小二乘高斯非线性回归分析提取白光干涉包络,求解耦合强度,验证了振动信号的幅度和频率与扫描速度有关,以及它对耦合强度检测精度的影响。结果表明该测试系统动镜的扫描速度在0.7～0.9mm/s时,偏振耦合强度的检测误差最小。
The principle of polarization mode coupling is theoretically analyzed, and the polarization coupling detection method based on white light interference is given. By controlling the mirror movement of the Michelson interferometer scanning arm by a stepper motor, the optical path difference (OPD) between two arms of the interferometer is changed to compensate the deviation of the two polarized lights due to the polarization coupling from the polarization maintaining fiber (PMF) The optical path difference at the time of exiting realizes the test of the polarization coupling strength and the position of the polarization maintaining fiber. During the scanning process, the vibration of the scanning arm mirror will have an adverse effect on the output signal. The vibration signal is simulated and experimentally studied, and its influence on the output signal is analyzed. Under different scanning speeds, the Hilbert transform and the least-squares Gaussian nonlinear regression analysis were used to extract the white interference envelope and calculate the coupling strength. The correlation between the amplitude and frequency of the vibration signal and the scanning speed was verified. influences. The results show that the detection error of the polarization coupling strength is the smallest when the scanning speed of the moving mirror of the test system is between 0.7 and 0.9 mm / s.