LPFG和FBG级联结构双参数光纤传感器研究

Study on dual-parameter fiber sensor based on LPFG cascaded with FBG structure

提出了一种长周期光纤光栅(LPFG)级联布拉格光纤光栅(FBG)的温度/应变双参数光纤传感器。利用飞秒激光直写制作LPFG并级连FBG,且FBG波谷位置为1 551.9 nm,LPFG波谷位置为1 559.1 nm,最高对比度为-12.7 d B。在30~70℃温度变化范围内对传感器温度特性进行测试,并在25℃超净环境下对0~500με应变变化范围内对传感器应变特性进行测试。实验结果表明,升温过程FBG中心波长发生红移,灵敏度15.00 pm/℃,线性度0.981 3;LPFG中心波长发生蓝移,灵敏度-11.75 pm/℃,线性度0.945 3。降温过程FBG中心波长发生蓝移,灵敏度18.25 pm/℃,线性度0.953 8;LPFG中心波长发生红移,灵敏度-15.42 pm/℃,线性度0.980 2。加载过程FBG中心波长发生红移,灵敏度0.93 pm/με,线性度0.991 5;LPFG中心波长发生蓝移,灵敏度-1.51 pm/με,线性度0.986 3。卸载过程FBG中心波长发生蓝移,灵敏度0.92 pm/με,线性度0.990 9;LPFG中心波长发生红移,灵敏度-1.51 pm/με,线性度0.972 8。结果表明,该光纤传感器灵敏度高,线性度好,可以同时动态实现应变和温度的测量。

A dual-parameter fiber sensor based on Long Period Fiber Grating （LPFG） cascaded with Fiber Bragg Grating （FBG） structure for temperature and strain is presented. The proposed fiber sensor is cascaded with LPFG micromachined by the femtosecond laser and FBG, and there are two dips for the transmission spectrum, namely FBG transmission dip at 1 551.9 nm and LPFG transmission dip at 1 559.1 nm with the fringe contrast - 12.7 dB. The temperature and strain characteristics of the proposed sensor were measured at 30 -70℃ and 0 ~ 500 με, respectively. Experimental results show that during the warming process, the FBG shows red shift with increasing wavelength, the sensitivity is 15.00 pm/℃, and the linearity is 0. 981 3; The LPFG shows blue shift with decreasing wavelength, the sensitivity is - 11.75 pm/℃, and the linearity is 0. 945 3. During the cooling process, the FBG shows blue shift with decreasing wavelength, the sensitivity is 18.25 pm/℃, and the linearity is 0. 953 8; The LPFG shows red shift with decreasing wavelength, the sensitivity is - 15.42 pm/℃, and the linearity is 0. 980 2. During the loading process, the FBG shows red shift with increasing wavelength, the sensitivity is 0.93 pm/με, and the linearity is 0. 991 5; The LPFG shows blue shift with decreasing wavelength, the sensitivity is - 1.51 pm/με, and the linearity is 0. 986 3. During the unloading process, the FBG shows blue shift with decreasing wavelength, the sensitivity is 0. 92 pm/με, and the linearity is 0. 990 9; The LPFG shows red shift with decreasing wavelength, the sensitivity is - 1.51 pm/με, and the linearity is 0. 972 8. The proposed sensor exhibits high sensitivity and good linearity for dual-parameter measurements.