中文摘要：

基于光纤布喇格光栅传感原理,分析了倏逝波光纤布喇格光栅（EWFBG）传感器的传感特征,建立了传感器反射波长随环境折射率变化的数学模型,并导出了波长灵敏度函数.结合函数分析了传感器的光纤光栅直径、外界液体折射率与灵敏度的关系,运用模式耦合理论进行模拟.结果表明,光纤传感区域纤芯越细,外界液体折射率与纤芯折射率相差越小,其反射中心波长漂移量越大,传感器灵敏度越高.通过对纤芯直径为φ6.2 μm和φ8.2μm在1.33～1.46环境折射率范围内的波长响应关系拟合,分别获得了1.25 nm和1.14 nm的波长变化量,灵敏度数量级为10-5～10-6,论证了分析结论的正确性.为EWFBG折射率传感器的设计、优化及应用提供了参考依据.

英文摘要：

The sensing characteristics of fiber Bragg grating evanescent wave is analyzed based on the principal of fiber Bragg grating. The mathematical model of the wavelength shift and the relational function of wavelength sensitivity are established. Sensor sensitivity formula is derived. Combining with sensitivity formula, the relationship between sensitivity and the fiber grating diameter, external medium refractive index are investigated. Coupledmode theory is applied in simulating. Simulation results show when the core of the optical fiber sensing region is thinner, the external medium refractive index difference of the core is smaller; when the shift of reflective center wavelength is greater, the sensitivity of the sensors is higher. For a fiber diameter of 6.2 μm and 8.2 μm respectively, by simulating the curves of the effective index versus ambient RI in the index ranges of 1.33- 1.46, the values of wavelength shift of 1.25 nm and 1.14 nm and the values of sensitivity of 10^-5 -10^-6 is obtained, which not only verifies the analysis conclusions and the measurement program for RI sensing with EWFBG, but also supplies refer- ences for the RI sensor design, optimization and the application.