膜层参数对长周期光纤光栅传感灵敏度的影响

Effects of Coated-film Parameters on Sensing Sensitivity of Long-period Fiber Grating Sensors

摘要:

基于耦合模理论,采用三包层光纤光栅模型,对镀有敏感薄膜的长周期光纤光栅的传感特性进行了分析。当敏感薄膜的光学参数(薄膜折射率和薄膜厚度)发生变化时,长周期光纤光栅传输谱中谐振峰处的透射率不变,但谐振峰会发生平移。进一步对薄膜折射率和薄膜厚度对其传感灵敏度的影响进行数值模拟,得到了结构优化的高灵敏度长周期光纤光栅传感器典型薄膜光学参数值。计算结果表明,该类型传感器对敏感薄膜折射率的分辨率可达10-9。研究结果为高灵敏度长周期光纤光栅传感器的结构优化及其传感应用提供了理论支持。

Abstract:

Based on the coupling-mode theory, the sensing characteristics of long-periode fiber grating (LPFG) coated with sensitive film were analyzed by using the triple-clad numerical model. When the optical parameters, such as thickness and refractive index of the film change, the transmissivity at the resonance peak in the transmission spectrum of LPBG remains unchanged, but the resonance peak shifts. Furthermore, the influence of changes of the refractive index and thickness of the film on the sensing sensitivity was simulated, and the typical optical parameters for high sensitivity and long period fiber grating sensors were obtained. Simulation results show that this type of sensor can measure the refractive index of the sensitive film with a resolution of 10-9.