中文摘要：

基于长周期光纤光栅（LPFG）包层有效折射率与包层半径的良好相关性，提出一种半腐蚀长周期光纤光栅的新颖设计。将一根长周期光纤光栅分成等长的两部分，用HF酸腐蚀其中的一半区域，此时整根LPFG可看成具有不同谐振波长的两个半长度LPFG的级联。利用传输矩阵方法和三层介质光纤模型的色散方程分析了该种LPFG的光谱特性：随着腐蚀段包层半径的减小，两个分裂峰谐振波长之间距离增大，且模式越高间距越大。同时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±8．9με和1．4℃。因此半腐蚀LPFG传感器可为解决LPFG交叉敏感问题提供有效方法。

英文摘要：

A new scheme about a semi-etched long-period fiber grating （LPFG） is proposed based on the excellent relation between cladding effective refractive index and cladding radius. A LPFG is divided into two sections with equal length. One section is eroded using HF acid. So the two sections can be regarded as two LPFGs with different resonant wavelengths. Spectral characteristics of this in-series LPFG are analyzed using dispersion equation of three- layer dielectric fiber. It is found that the distance between two resonant wavelengths increases with the decrease of the cladding radius, and the distance also increases with higher-order mode. At the same time, strain and temperature are measured synchronously, and the sensing precisions of strain and temperature are ± 8.9 με and 1.4 ℃, respectively. Semi-etched long period fiber grating can solve the cross sensitive problems of different physical quantities effectively.