传输光纤对四态法偏振相关损耗测试的影响

Impact of Transmission Fiber on Polarization Dependent Loss Testing Based on Four States Method

基于四态法的偏振相关损耗（PDL）测试技术，通常需要用光纤连接偏振控制器和待测器件。由于光纤普遍存在双折射效应，会使测试光的偏振态在经过传输光纤后发生改变，有可能给PDL测试带来影响。利用延迟波片近似和传输矩阵方程进行了理论分析，并利用偏振控制器、偏振分析仪和功率计等仪器进行了实验验证。实验结果表明，传输光纤虽然会影响测试光的偏振态，但对测试四态光在邦加球上的相对位置和PDL测试结果的影响极小，与理论分析保持一致。为深入研究PDL测试技术提供了一定的技术支持和经验借鉴。

The polarization dependent loss （PDL） testing technology based on four states method always needs the connection between polarization controller and device under test （DUT） by using the fiber. The birefringence effect of fiber will change the state of polarization of light, which may affect the PDL testing. Using waveplate approximation and transmission matrix equations, we study it theoretically. While the polarization controller, polarization analyzer and power meter are used for the experimental verification. The results show that although the transmission fiber will affect the state of polarization of light, the impact on test results of the relative position of the four states of light on the Poincaré sphere and PDL testing is very small, which is consistent with theoretical analysis. These conclusions will provide certain technical support and theoretical tools for further study on PDL technology.