带宽调制型单光纤光栅温变无补偿位移传感

报道了利用反射谱带宽调制和光强差分探测技术实现单一光纤光栅温变无补偿位移精确测量的新方法。设计了一种结构新颖的曲臂梁位移传感装置,结合光波导理论与材料力学原理分析了光纤光栅在高斯应变作用下光栅反射谱侧向梯度展宽的成因,理论推导了特殊结构梁在外力作用下光栅反射谱带宽/反射光强与压力之间的响应关系。光栅反射谱侧向梯度展宽的同时反射光强线性增加,利用光强差分检测方法消除光源出光抖动的影响,提高了位移测量精度。基于带宽调制的光纤光栅位移传感方法免受温度变化的影响,在-10℃~80℃的温度变化范围内,测量误差小于1.2%,实现了单光纤光栅温变无补偿位移测量。

Research on Bandwidth-Modulated and Temperature-Independent Single Fiber Bragg Grating Displacement Sensing

The temperature-independent fiber Bragg grating (FBG) displacement measurement based on optical reflection spectrum bandwidth modulation and differential optical power detection is proposed and experimentally demonstrated. A specially designed bending cantilever beam is used to induce Gauss strain distribution along the sensing FBG, resulting in Bragg wavelength shift and bandwidth modulation. Based on the theory of optical waveguide and material mechanics, the causation of reflection spectrum lateral gradient broadening of fiber Bragg grating under the Gauss strain distribution is analyzed, and the force-to-bandwidth broadening relation and force-to-optical power relation are formulized based on cantilever beam special structure with a lateral gradient broadening of FBG spectrum bandwidth and a linear increase of reflection optical power. For a temperature range of -10 ℃～80 ℃, the measured displacement fluctuates less than 1.2% without any temperature compensation.