腐蚀包层法调谐长周期光纤光栅及增强折射率敏感特性的研究

Research on Tuning LPFG and Increasing Refractive Index Sensitivity Characteristics by Etching Cladding

从理论与实验上研究了腐蚀包层法增强长周期光纤光栅环境折射率敏感特性和调谐透射谱的机制,结果表明,随着光栅区包层半径的减小,各阶包层模谐振波长向长波方向移动,环境折射率敏感特性随之显著增强。在用HF酸溶液腐蚀光栅区包层的实验测试中,先后观察到4个损耗峰,其中第2个损耗峰在包层半径减小约4.11μm、谐振波长向长波方向移动了约117.19 nm时,环境折射率传感特性增强了约3倍,这为制备高精度液体浓度/折射率传感器提供了重要依据。

A mechanism for increasing the ambient refractive -index sensitivity characteristics of the long - period fibre grating （LPFG） and tuning the transmission spectrum by etching cladding was researched theoretically and experimentally. The result showed that the resonant wavelength of each order of cladding mode moved towards the long wave and the ambient refractive -index sensitivity characteristics increased significantly as the cladding radius of the grating zone decreased. Four loss peaks were observed in the experiment of etching the cladding of the grating zone with the HF acid. As for the second loss peak, the ambient refractive - index sensitivity characteristics increased by about four times when the cladding radius decreased by about 4.11 μm and the resonant wavelength moved by about 117.19 nm towards the long wave. The research lays a foundation for precision solution -concentration/refractive -index sensors.