一种两段式FBG应变和温度同步测量的实现

Strain and temperature simultaneous measurement using a two-section FBG

为解决光纤布拉格光栅(FBG)的应变和温度交叉敏感性问题,本文基于FBG纤芯有效折射率与纤芯半径的良好相关性,提出一种半腐蚀FBG的新颖结构。即一根FBG被分成等长两部分,用HF酸腐蚀其1/2区域直到纤芯半径。采用传输矩阵法和纤芯基模有效折射率的色散方程对两段式FBG建模,利用Mathcad 15计算软件进行数值仿真和模拟。仿真结果表明,FBG反射峰发生分裂,即一个反射峰分裂为两个,且当纤芯半径变小时,腐蚀段FBG谐振波长蓝移,而未腐蚀段FBG谐振波长基本不变;纤芯半径越小,两段FBG谐振波长的间距越大。实验结果表明,实现了应变和温度的同步测量,得到应变和温度的传感精度分别为7.2με和1.1℃。

The strain sensing sensitivity of fiber Bragg grating（FBG）is very high,but it is necessary to solve the temperature cross-sensitive problem effectively in practical applications.Based on the relationship of the core effective refractive index of the FBG and the core radius,a new type FBG sensor composed of two sections is proposed.An FBG is divided into two sections with equal length.One of them is eroded using HF acid.So the two sections can be regarded as two FBGs with different resonant wavelengths.Spectral characteristics of this in-series FBG and analyzed using the dispersion equation of twolayer dielectric fiber and the transfer matrix method.The simulation results show that the resonant band is split due to the particularity of the FBG structure.As the core radius reduces,the resonant wavelength of the etched section of FBG presents a blue shift,while the resonant wavelength of the other section of FBG remain basically unchanged,the distance between two resonant wavelengths is increased with the decrease of the core radius.At the same time,strain and temperature are measured,and the sensitivities of strain and temperature sensing are 7.2μεand 1.1℃,respectively.