基于长周期光纤光栅的FBG解调方法

FBG demodulation method based on long-period fiber gratings

摘要: 研究了基于长周期光纤光栅（long-period fiber gratings, LPFG）的光纤布拉格光栅（fiber Bragg gratings, FBG）解调方法，该方法利用 LPFG 的透射谱作为边沿滤波器解调 FBG，其解调性能主要取决于LPFG的透射光谱深度。详细分析了CO₂激光写制法对透射光谱的影响，制作了透射光谱深度为25 dB的LPFG，并采用该光栅搭建了FBG解调装置，将FBG粘贴于金属应变片表面，测试了其静态与动态响应特征。实验结果表明：该方法制作简单，成本低，具有较好的线性动态范围，可以实现较高灵敏度的FBG解调。

Abstract: The demodulation method of fiber Bragg gratings (FBG) based on long-period fiber gratings (LPFG) was studied. The transmission spectrum of LPFG was used as the edge filter to demodulate the FBG, and the demodulation performance mainly depended on the transmission spectrum depth of LPFG. The influence of CO₂ laser writing technique on the transmission spectrum was analyzed in detail, and the LPFG with transmission spectrum depth of 25 dB was manufactured and used as the FBG demodulation device. The demodulation system was built with the FBG pasted on the surface of the metal strain sheet. The static and dynamic response of the sensing system was tested. The experimental results show that the proposed method has the advantages of simple production process, low cost, good linear dynamic range and higher sensitivity.