通过在基于高双折射光纤Sagnac干涉仪的Sagnac环内增加一段高双折射光纤并控制两段高双折射光纤的熔接角度，设计制作了二阶Loyt-Sagnac干涉仪结构.利用Jones矩阵对反射谱特性进行了理论推导，对光束入射角度和高双折射光纤长度进行了优化，并对两种结构的干涉仪温度传感器进行仿真和实验.仿真结果表明，利用二阶Loyt-Sagnac干涉仪结构的游标效应，能提高其作为温度传感器时的灵敏度；实验结果证明，单段Sagnac环干涉仪温度传感器灵敏度为－1.46 nm/℃，而使用二阶Loyt-Sagnac干涉仪的温度传感灵敏度为－17.99 nm/℃，提高了约12.32倍.

The second order Loyt-Sagnac interferometer was constructed by inserting two sections of highly birefringence fibers into the fiber loop and adjusting the fusion splicing angle. The transmission spectrum of the highly birefringence fiber Sagnac interferometer was calculated by using the Jones matrix analysis. The polarization angle of input light and the lengths of highly birefringence fibers were optimized. These two kinds of temperature sensors were simulated and experimented. The Simulation results show that the temperature sensitivity of the second order Loyt-Sagnac configuration can be enhanced because of its Vernier effect. The experimental results show that the temperature sensitivity is increased from －1.46 nm/℃ to －17.99 nm/℃ by using the proposed structure, increased 12.32 times.