A novel design for axial strain measurement using a polarization maintaining fiber Bragg grating (PMFBG) concatenated with a Sagnac fiber loop mirror is proposed and demonstrated. The PMFBG acts as a sensor head, and the Sagnac fiber loop mirror serves as a filter to convert wavelength difference variation caused by the axial strain to optical power change. The experimental results show that in the range of 0~480 με, the sensitivities of the wavelength of the two resonant directions is 0. 002 nm/με, and the sensitivities of the resonant peaks power of fast and slow of PMFBG are 0. 010 6 dB/με and 0. 007 dB/με respectively. And their pertinence coefficients are more than 0. 99. The different sensing characteristics of its two resonant directions on axial strain can be used to solve the cross-sensing problem of the fiber Bragg grating.%介绍了一种研究保偏光纤光栅(PMFBG)轴向应变传感特性的结构,并对其进行了实验研究.将PMFBG和高双折射光纤Sagnac环串联起来,PMFBG做为传感头,高双折射光纤Sagnac环作为边沿滤波器件用于将PMFBG两个谐振峰由轴向应变引起的波长变化转换成功率的变化.研究结果显示:在0～480με的范围内,PMFBG快轴和慢轴谐振峰波长的轴向应变敏感系数为0.002 nm/με,对应功率的轴向应变敏感系数分别为0.010 6 dB/με和0.007 dB/με,其线性拟合度均在0.99以上.此结构中PMFBG两个偏振方向对应的功率轴向应变敏感系数的不同可以解决光纤光栅的交叉敏感问题.
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