长周期光纤光栅折射率传感器的结构优化

为了提高长周期光纤光栅对环境介质折射率的传感灵敏度,提出一种长周期光纤光栅的周期和包层半径的结构优化.基于长周期光纤光栅的耦合模理论,分析了长周期光纤光栅的周期和包层半径的大小分别与环境介质折射率传感灵敏度的关系,讨论了长周期光纤光栅的周期和包层半径对折射率传感的影响以及控制光栅周期与包层半径对折射率传感的重要性.为使优化的长周期光纤光栅具有实用性,谐振波长设计在1.55 μm的常规波长范围,经过多次摸拟实验,提出最佳优化参量为：Λ=380 μm,rcl=17 μm,对环境介质折射率从1.26~1.38不同值的实验测试,折射率传感灵敏度达到0.000 12,长周期光纤光栅的结构优化获得理想的预期效果.

Optimization of Long-period Fiber Grating for Refractive-index Sensor

Optimization structure of cladding radius and grating periods of long-period fiber grating (LPFG) was proposed,in order to achieve a high sensitivity of sensing the refractive-index of the external medium.Based on the coupled-mode theory of the LPFG,a theoretical analyzation was carried out between the cladding radius and grating period,and surrounding refractive-index,respectively.Effects of the variation of the cladding radius and grating period on the refractive- index sensing were discussed.Both of these parameters were found to be equivalently important to control the refractive-index sensing.Optimizing parameters of the grating are Λ=380 μm and rcl=17 μm in order to achieve a good apply of the LPFG with resonance wavelength in the 1.55 μm common application region.Variation of external medium refractive-index from 1.26 to 1.38 was tested and the achieved refractive-index sensing sensitivity is 0.000 12.Optimization structure of the LPFG achieves a good result.