为提高Sagnac型温度传感器的测温范围和灵敏度，提供了一种具有高双折射高温度灵敏度特性的光子晶体光纤设计方法。通过在光纤空气孔内填充温敏液体材料，使光纤具有良好的温敏特性。在COMSOL中建立该光子晶体光纤的电磁场模型并对光纤特性进行分析计算，利用有限元法分析结构参数对双折射和光纤双折射温度灵敏度的影响，并在所确定结构基础上研究了温敏液体的填充方式和填充液体类型对光纤温敏特性的影响。确定了最优的结构和液体填充方式，最优情况下该光纤的双折射温度灵敏度能够达到2.050 7×10^-5/℃，在1 550 nm处可获得5.96×10^-2的双折射。将2 mm光子晶体光纤应用于Sagnac型温度传感器中并进行传感性能仿真分析，利用多项式拟合的方法对结果数据进行拟合以分析传感器的温度灵敏度，提高拟合准确性、减小测量误差。结果表明在0~75 ℃范围内传感器平均灵敏度可达11.28 nm/℃，与现有典型Sagnac型温度传感器相比，本文Sagnac型温度传感器在尽量减小光纤长度的基础上获得了较高的温度灵敏度，并且测温范围更大、准确性更高。因此，该传感器在温度测量领域有一定的应用前景。

Optical fiber sensors are widely valued by scholars for their simplicity of manufacture, resistance to electromagnetic interference, chemical resistance and ease of distributed measurement. Interferometric fiber optic temperature sensors use the phase change of light to achieve sensing. Sagnac interferometer based temperature sensors are widely used in the sensing field due to their high sensitivity and ease of production. The change in the phase difference can lead to a shift in the interference spectrum, which can be analyzed as a function of temperature. It is an important research direction to design special fibers in Sagnac ring to improve the sensing performance of Sagnac-type temperature sensors. The flexible structural design and air-hole fill ability of photonic crystal fibers offer the possibility to achieve excellent properties of optical fibers. In order to improve the temperature range and sensitivity of Sagnac-type temperature sensors, a photonic crystal fiber design method with high birefringence and high temperature sensitivity properties is provided. The high birefringence of the fiber facilitates the demodulation of Saganc-type temperature sensors and the high temperature sensitivity of the fiber facilitates the sensing sensitivity of Sagnac-type temperature sensors. As the optical fiber itself has limited sensitivity to temperature, it can be made to have good temperature sensitivity by filling the air holes of the fiber with temperature sensitive liquid material. The electromagnetic field model of this photonic crystal fiber is developed in COMSOL and the fiber properties are analyzed and calculated. The effect of structure parameters on the birefringence and the temperature sensitivity of the fiber is analyzed using the finite element method, and the effect of the filling method and the type of filling liquid on the temperature sensitivity of the fiber is investigated on the basis of the determined structure. The optimal structure and filling method are determined. The results show that selective filling can achieve higher temperature sensitivity than full filling, and ethanol is the most suitable filling fluid compared to other temperature sensitive liquids. Under optimal conditions, the fiber achieves a temperature sensitivity of 2.050 7×10^-5/℃ and a birefringence of 5.96×10^-2 at 1 550 nm. The 2 mm length of this fiber is used in a Sagnac type temperature sensor to analyze the sensing characteristics by simulation, increasing in temperature from 0 ℃ to 75 ℃ in steps of 5 ℃ and using the trough of the transmission spectrum as a reference point to analyze the variation of the transmission spectrum with temperature. A polynomial fitting method is used to fit the wavelength and temperature in order to analyze the temperature sensitivity of the sensor, improve the accuracy of the fit and reduce the measurement error. The results show that the average sensitivity of the sensor can reach 11.28 nm/℃ and the maximum sensitivity is 15.94 nm/℃ in the range of 0~75 ℃, with an average temperature measurement error of 0.126 9 ℃. Compared to existing typical Sagnac temperature sensors, the Sagnac temperature sensor in this paper achieves a higher temperature sensitivity with a minimized fiber length, a larger temperature range and higher measurement accuracy. Therefore, the sensor has a promising application in the field of temperature measurement.