基于光波导理论和传输矩阵法, 研究光纤包层被完全腐蚀后的高斯变迹光纤布拉格光栅(FBG)在非均匀外部介质环境下的反射谱特性。仿真过程中, 分别考虑高折射率区(1.43~1.45)和低折射率区(1.33~1.36)两种情况, 同时假设该非均匀外部介质折射率(SRI)呈不同的线性函数分布。仿真结果表明, 高斯变迹FBG的谱带宽、谱强度特性与SRI沿光栅轴向的线性分布梯度密切相关。随着SRI梯度增加, 反射谱的3dB带宽也逐渐增加, 此时高、低折射率区的梯度灵敏度分别为3.775×103nm·mm/riu和3.72×103nm·mm/riu。研究结果对高斯变迹FBG用于生化传感领域的非均匀介质测量具有一定意义。

Based on the fiber waveguide theory and the transfer matrix method, researched is the reflection spectrum of Gaussian apodized FBG with the cladding completely corroded under uneven medium. During the stimulation process, high refractive-index(1.43~1.45) area and low refravtive area(1.33~1.36) are considered respectively. Meanwhile, it is supposed the uneven SRI shows different linear function distributions. Simulations show the spectrum bandwidth and spectrum intensity of Gussian apodized FBG depend on the SRI along the grating axial linear distribution gradient. As SRI gradient increases, the gradient sensitivity of high refractive index area and low refractive index area is 3.775×103nm·mm/riu and 3.72×103nm·mm/riu, respectively.