中文摘要：

利用长周期光纤光栅（LPFG）和保偏光纤（PMF）Sagnac环透射光谱的调制特性，设计了温度和折射率同时区分测量系统。通过监测LPFG嵌入Sagnac环的透射谱中谐振峰波长和强度的变化，测定了波长和强度对温度和折射率的灵敏度系数，构建了传感系数矩阵。实验发现，谐振峰波长随温度变化，谐振峰强度随折射率变化，实现了温度与折射率的区分测量。实验测得该系统的温度灵敏度0．1286nm／℃，折射率灵敏度为49．38dB／RIU。实验结果验证了方案的正确性，且实验系统搭建简便，体积小，成本低，具有一定的应用前景。

英文摘要：

A simultaneous measurement system for temperature and refractive index is proposed using a long period fiber grating （LPFG） and a polarization maintaining fiber （PMF） Sagnac loop, based on which the transmission spectrum of the fiber Sagnac interferometer is modulated by the LPFG. Through measuring the wavelength shifts and the intensity changes of a resonance dip of the system, the wavelength and the intensity response sensitivities to temperature and refractive index are obtained, and the sensitivity coefficient matrix is constructed. The experimental results show that the wavelength of the dip varies with temperature and the intensity of the dip changes with refractive index The temperature sen- sitivity of the system is 0. 128 57 nm/℃ ,and the refractive index sensitivity of LPFG is 49. 380 32 dB/ RIU. The experimental system is small and easy to set up, whose cost is relatively low and it has good application prospect.