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光纤Sagnac环滤波器用于光纤布拉格光栅(FBG)传感器波长解调时受环境温度影响很大,为此提出一种可消除温度影响的高稳定解调新方法,介绍了系统光路和解调器的工作原理。将带有一段保偏光纤的Sagnac环作为边缘滤波器,分布反馈(DFB)激光器的单波长激光作为参考光,对FBG波长信号和参考光信号同时进行滤波。在同一时间探测经Sagnac环滤波器输出的透射光强度和反射光强度,进行光强信号归一化处理并采用差动检测方法分析。理论分析和实验结果表明,该解调方法基本消除了Sagnac环滤波器的温度效应,提高了解调系统的稳定性。在1302~1318nm波长范围内,解调装置的温度漂移为2.4×10-4 nm/℃,是未封装补偿无参考光的Sagnac环滤波器透射谱温度漂移的1.8×10-4倍。
Fiber Sagnac ring filter is widely used in FBG sensor because of the influence of ambient temperature when it is demodulated. Therefore, a new high stability demodulation method is proposed to eliminate the influence of temperature. The optical path and demodulator working principle. A Sagnac ring with a polarization maintaining fiber is used as an edge filter and a single-wavelength laser with a distributed feedback (DFB) laser is used as a reference light to filter the FBG wavelength signal and the reference light signal simultaneously. At the same time, the transmitted light intensity and the reflected light intensity output by the Sagnac ring filter are detected, and the signal of light intensity is normalized and analyzed by the differential detection method. Theoretical analysis and experimental results show that the demodulation method basically eliminates the temperature effect of the Sagnac loop filter and improves the stability of the demodulation system. In the wavelength range of 1302 ~ 1318nm, the temperature drift of the demodulation device is 2.4 × 10-4 nm / ℃, which is 1.8 × 10-4 times of the temperature drift of the transmission spectrum of Sagnac ring filter with no reference light without compensation.