针对高温条件下应变测量受限问题, 对飞秒脉冲激光刻写的Ⅱ型纯石英芯光纤光栅(FBG)的温度及应变特性进行了研究。实验结果表明, 纯石英芯FBG在20~1000 ℃温度范围内表现出良好的线性度, 相关系数为0.9996, 温度灵敏度为14.07 pm/℃; 纯石英芯FBG在400 ℃及以下的高温环境中加载均匀应变时表现出良好的波长稳定性,温度超过500 ℃时的应变加载导致光纤伸长, 引起中心波长的红移。

In order to solve problem of the strain measurement limitation under high temperature, the temperature and strain characteristics of the type II pure-quartz-core fiber Bragg grating (FBG) written by femtosecond pulse laser are studied. Experimental results show that when the temperature is ranging from 20 ℃ to 1000 ℃, the pure-quartz-core FBG exhibits good linearity with the correlation coefficient of 0.9996 and the temperature sensitivity of 14.07 pm/℃. When the temperature is under 400 ℃, the pure-quartz-core FBG exhibits good wavelength stability under the uniform strain. When the temperature is above 500 ℃, the strain loading leads to fiber elongation and the red shift of the center wavelength.