保偏光纤应力分布与双折射特性的数值分析

Numerical Analysis of Stress Distribution and Birefringence Characteristics of Polarization-Maintaining Fiber

摘要: 通过有限元仿真对熊猫型保偏光纤(PMF)内部的应力分布以及双折射特性进行分析，得出提升PMF双折射特性的方法。根据光纤内部各部分温度特性不同，得出了减小外界环境温度能增强光纤双折射的结论。利用COMSOL有限元仿真软件建立了PMF截面应力–双折射模型。结果表明：当应力区半径增加10 μm时，双折射值增加5.753 × 10⁻⁴；当应力区中心点距纤芯中心点增加4 μm时，双折射值减少2.6121 × 10⁻⁴；应力区热膨胀系数、杨氏模量以及泊松比分别增加时，光纤的双折射效应也随之增加；光纤内部双折射值与外界温度变化率为−4.94 × 10⁻⁷。该研究结论为改进基于级联保偏光纤的传感器提供了理论依据。

Abstract: The stress distribution and birefringence characteristics of Panda polarization-maintaining fiber were analyzed by finite element simulation, and the method to improve the birefringence characteristics of PMF was obtained. According to the different temperature characteristics of each part inside the fiber, it is concluded that reducing the ambient temperature can enhance the birefringence of the fiber. The PMF cross-section stress-birefringence model was established by COMSOL finite element simulation software. The results show that the birefringence value increases by 5.753 × 10⁻⁴ when the stress radius increases by 10 μm. When the distance between the center point of stress zone and the center point of fiber core increases by 4 μm, the birefringence value decreases by 2.6121 × 10⁻⁴. When the coefficient of thermal expansion, Young’s modulus and Poisson’s ratio increase respectively, the birefringence effect of fiber also increases. The change rate between the internal birefringence value and the external temperature is −4.94 × 10⁻⁷. The conclusion of this study provides a theoretical basis for improving the sensor based on stage joint polarization fiber.