为了研究双折射率对双折射光纤环境轴向应变灵敏度的影响，选取双折射应变系数相同，双折射率不同的双折射光纤，通过数值模拟得到轴向应变灵敏度随双折射率变化的趋势。模拟结果表明轴向应变灵敏度随着双折射率增加而减小。实验选取不同双折射率光纤构建光纤环境轴向应变传感器，进行应变灵敏度对比实验，将获取的双折射率、轴向应变灵敏度数据进行曲线拟合，实验拟合曲线与仿真曲线呈现良好的一致性。结果表明，选择双折射率较小的双折射光纤作为敏感元件可以提高双折射光纤环境轴向应变灵敏度，但是双折射率存在一定下限，否则将产生微弱的干涉光谱而无法进行轴向应变测量。

To investigate influence of birefringence on axial strain sensitivity of birefringence fiber loop mirror, change of axial strain sensitivity with birefringence is drawn by numerical simulation for the same strain dependent birefringence coefficient and different birefringences fibers. The simulation result shows that the axial sensitivity reduces with the increase of birefringence. The axial strain sensitivities of different birefringence fiber loop mirrors are compared by experiment. The curve of birefringence versus the axial strain sensitivity is fitted. The experimental fitting curve is in agreement with the simulation one. The result shows that the axial strain sensitivity can be improved by choosing a low birefringence fiber, but the birefringence can not be too low to measure axial strain because of generating weak interference spectrum.