长周期光纤光栅气敏薄膜传感器结构优化

基于三包层长周期光纤光栅模型,研究了包层表面涂覆一层溶胶凝胶气敏薄膜的长周期光纤光栅化学传感器的灵敏度Sn与薄膜光学参量(折射率n3和厚度h3)和光纤光栅结构参量(光栅周期、折变量和光栅长度)之间的关系。采用最优化数值方法,找到了获得高灵敏度所需的最佳膜层光学参量和光栅结构参量。理论计算表明,该类型传感器对膜层折射率的测量分辨率高达10-8。实验上制作了对乙醇气体敏感的传感器,并证实了传感器结构优化的必要性。

Structure Optimization of Long-Period Fiber Grating Gas-Sensing Film Sensors

Based on a triple-clad numerical model, a long-period fiber grating chemical sensor coated with the sol-gel gas-sensing films on the cladding of the fiber grating region is studied. The relation between the sensitivity S_n and the thin film optical parameters (thickness h_3 and refractive index n_3), and the fiber grating parameters (the grating period, the core index modulation and the grating length) is analyzed. By using optimization method, the optimal optical parameters of thin film and fiber grating parameters are obtained to make the sensor highly sensitive. Numerical simulation shows that the sensitivity of this scheme to refractive index of the films is 10~ -8 . In the end a long-period fiber grating sensor sensitive to C_2H_5OH is fabricated, which proves the necessity of the structure optimization of the sensor.