三波片偏振态变换器误差分析

在相干光通信和高速光纤通信等领域，要求偏振变换器具有高的偏振变换精度。对由两个可独立旋转的λ／4波片和一个可独立旋转的λ／2皮片组成的三波片偏振变换器的偏振变换误差进行了详细的分析。利用二维几何方法推导出了由波片方位角误差造成的偏振变换误差模型，并进行了数值计算。研究结果表明，三波片不同的组合方式对偏振态的变换精度有影响。其中，λ／4 λ／2 λ／4组合具有最高的偏振变换精度，λ／2 λ／4 λ／4次之，λ／4 λ／4 λ／2的最差；经三种偏振变换器变换后偏振态的方位角的变换误差较大，变换后偏振态的椭率角的误差很小；三种偏振变换器都可以实现较高精度的任意偏振态变换。

Error Analysis on Three-Waveplate Polarization State Transformers

The polarization transform errors of three-waveplate polarization transformers (TWPTs), which consist of one half-waveplate (λ/2) and two quarter-waveplates (λ/4), are discussed detail. The error models of the TWPT using a new and simple two dimensions geometry method instead of traditional Poincaré sphere method are deduced and numerically calculated. The results of investigation show that the errors of the TWPTs are dependent on the different combinations of one λ/2 and two λ/4, and according to the accuracy of TWPTs, λ/4+λ/2+λ/4 is the best, λ/2+λ/4+λ/4 is better and λ/4+λ/4+λ/2 is good. After polarization transform, the errors of azimuth angle and ellipticity angle are rather large and minor respectively and the TWPTs have enough accuracy to meet the applications in the field of coherent optical communications and optical fiber communication systems.