采用Sagnac干涉仪结构，设计了一种高双折射光子晶体光纤环镜温度传感器。光子晶体光纤温度稳定性好，通过向高双折射光子晶体光纤空气孔填充热光系数高的液体材料乙醇，从而实现温度传感的目的。采用平面波展开法，分析了高双折射光子晶体光纤的双折射与传输波长和温度的关系。理论分析表明，填充乙醇后，高双折射光子晶体光纤的双折射随着传输波长和温度的增加而增加，且双折射与温度成线性关系。实验中将一段填充乙醇的高双折射光子晶体光纤与3 dB耦合器熔接制作成Sagnac干涉仪结构的光纤环镜，当温度从 45 ℃升至80 ℃时，光谱仪上观察到凹点λi向短波方向漂移了309.280 nm，温度灵敏度高达8.837 nm/℃。

A highly birefringent photonic crystal fiber loop mirror temperature sensor based on Sagnac interferometer structure is designed. As the photonic crystal fiber has good temperature stability, in order to achieve the temperature sensing, ethanol which has a high thermal coefficient is filled into the air holes of the high birefringence photonic crystal fiber. Using plane wave expansion method, the relationship between birefringence of the highly birefringent photonic crystal fiber and transmission wavelength, and that between birefringence and temperature are analyzed. Theoretical analysis shows that: filled with ethanol, the birefringence of high birefringence photonic crystal fiber increases with the increase of the transmission wavelength and temperature, besides, there is a linear relationship between birefringence and temperature. In the experiment, a piece of high birefringence photonic crystal fiber filled with ethanol is welded with a 3 dB coupler to form a fiber loop mirror. When the temperature rises from 45 ℃ to 80 ℃, the concave point drift of 309.280 nm towards the short wavelength is observed on spectrum analyzer. The sensitivity is as high as 8.837 nm/℃.