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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。
Based on the good correlation between the effective refractive index and the cladding radius of long period fiber grating (LPFG), a novel design of a semi-corrosive long-period fiber grating is proposed. A long-period fiber grating is divided into two parts of equal length and the half of the area is etched with HF acid. In this case, the whole length of LPFG can be regarded as a cascade of two half-length LPFGs with different resonance wavelengths. The spectral characteristics of this kind of LPFG were analyzed by using the transfer matrix method and the dispersion equation of the three-layer dielectric fiber model. As the radius of the cladding decreases, the distance between the two splitting peaks increases, and the higher the mode spacing The bigger At the same time, simultaneous measurement of strain and temperature was achieved, and the sensing accuracy of strain and temperature were ± 8.9με and 1.4 ℃, respectively. So semi-eroded LPFG sensor can provide an effective method to solve the LPFG cross-sensitivity problem.