基于Sagnac干涉仪的保偏光纤拍长测试技术

Technology of measuring the beat-length of polarization maintain optical fiber based on Sagnac interferometer

分析了一种由单模光纤耦合器和保偏光纤组成的混合光纤Sagnac干涉仪的反射谱和透射谱,揭示了这种干涉仪的光谱调制特性.基于其透射光谱的极值点特征,提出了一种简单、高精度的保偏光纤拍长测试技术并进行了精度分析,确定了待测保偏光纤长度的优化参数;搭建实验系统进行了实际测试.实验结果和理论估计一致.研究表明:该技术操作方便、测量可靠,拍长测量精度可优于0.01 mm.

The reflectance and transmission spectrum of the hybrid Sagnac fiber optic interferometer which is consist of single mode fiber coupler and polarization maintain optical fiber were investigated and the modulation character of the spectrum was illustrated.A simple measurement method for the beat-length of polarization maintain optical fiber was proposed based on the character of the transmission spectrum.And the optimization parameter for the measurement based on the error analysis was obtained.The experimental system was set up and the experimental results agree well with the theoretical prediction.The result shows that this technique has the advantage of simple in principle and high precision,the accuracy of the beat-length measurement is better than 0.01mm.