基于宽带光纤圆起偏器的保偏光纤拍长测量

Beat-Length Measurement of Polarization Maintaining Fibers Based on Broadband Fiber Circular Polarizers

提出了一种基于偏光干涉效应测量保偏光纤拍长的新方法。利用宽谱光源和两个宽带光纤圆起偏器,与被测保偏光纤组成了全光纤的测试系统。理论分析表明,相比于光纤线偏振器构成的偏光干涉测量系统,圆偏振器可以克服保偏光纤主轴之间的角度对输出干涉光对比度的影响。采用该方法对某熊猫型保偏光纤的拍长进行了验证性实验研究,实验结果和理论分析相吻合,保偏光纤拍长测量精度和重复性为0.1mm,干涉信号对比度可达0.9以上。由于光纤器件间无需精确对轴,因此该方法光路结构简单,操作要求较低。

A new method to measure the beat-length of polarization maintaining fibers is presented. The key components of the all-fiber measuring system are a broadband light source and two broadband fiber circular polarizers. Theoretical analysis shows that, compared with the polarization interference system made up by fiber linear polarizers, circular polarizers can eliminate the influence of the angles between the axis of polarization maintaining fibers on the visibility of the interference fringe. The beat-length of a panda polarization maintaining fiber is investigated for verification. Experimental results are in good agreement with the theoretical analysis. The accuracy and repetition of beat-length measurement are 0.1 mm, and the visibility of the interference fringe is better than 0.9. Since there is no need for accurate angle adjustment between polarization maintaining fiber devices, the measurement system has the advantages of simple structure and low operation requirement.