长周期光纤光栅温度传感器应变交叉敏感的研究

长周期光纤光栅是透射谱光栅,纤芯基模与同向各阶包层模发生耦合,谐振波长和幅值对外界环境的变化非常敏感,比传统布拉格光纤光栅具有更好的温度、应力、弯曲、扭曲、横向载荷、折射率等的传感特性.由于长周期光纤光栅对两个或者多个参量都是敏感的,当光纤光栅用于传感测量时,很难分辨出各个参量分别引起的被测量的变化,交叉敏感问题比布拉格光纤光栅严重的多.交叉敏感是光纤光栅传感中的关键问题.分析了目前较为典型的解决策略和方案,在此基础上提出了联系的思想和解决方案,提出并实验验证了一种解决长周期光纤光栅温度传感测量中应力与温度的交叉敏感问题.充分利用了LPFG温度与应变交叉敏感的现象,利用联系的思想,将应变对温度的负面干扰转变为正面的增敏.

Solutions of strain and temperature cross-sensitivity of long period fiber grating temperature sensing

Long period fiber grating is transmission spectrum grating,which is fiber core basic model coupling with cladding modes, and resonance wavelength and amplitude of long period fiber grating is very sensitive to the change of external environment, long period fiber grating has better sensing properties than traditional FBG in temperature, stress, bending, distortion, lateral load, refractive index, and so on. Because the long period fiber grating was sensitive to two or more parameters, when optical fiber grating for sensing measurement, it was difficult to distinguish the change of the measured caused by the various parameters respectively, and cross-sensitivity problem of long period fiber grating was more serious than that of the fiber Bragg grating. The cross-sensitivity was the key problem of fiber grating sensors. Based on analysis of the current typical ideas and solutions, one idea and solution of relation was proposed in this paper, and solves cross-sensitivity between stress and temperature in the long period fiber grating temperature sensing measurement. This idea makes full use of the cross-sensitivity phenomenon of the temperature and strain of LPFG and turns the negative interference of the strain on the temperature to positive sensitization.