研究了多重曝光诱导载氢光纤布拉格光栅折射率变化的机理及规律.基于二步法的光敏模型分析了多重曝光下载氢光纤光栅的折射率变化,得到了不同初始折射率分布下多重曝光量增长与光栅折射率变化的关系,建立了光纤光栅平均折变量和调制折变量变化数学模型；采用193 nm 紫外激光实验研究了布拉格光栅在多重曝光过程中波长、反射率的变化特性.研究结果表明,多重曝光下光栅中心波长红移,红移量与再曝光条件有关；光栅反射率先增大后趋于稳定,反射率增长速度与再曝光条件有关,趋于稳定的极值由光栅初始曝光分布决定.

Refractive index changes of hydrogen loaded fiber Bragg grating induced by multiple post-exposure are researched.Changes of fiber grating refractive index induced by multiple post-exposure are analyzed based on the two-step process photosensitive model.The relationship between grating refractive index and multiple postexposure is obtained under different initial refractive index distribution,and the mathematical models about mean refractive index and modulation refractive index of fiber grating are built up.Furthermore,variation characteristics of fiber Bragg grating wavelength and refractive index under multiple post-exposure are experimentally studied using 193 nm UV laser.The results show that,under multiple post-exposure,the grating wavelength gets red shifted and the shift quantity is related to post-exposure conditions.The grating refractive index increases firstly and then tends to be stable.The growth rate is related to post-exposure conditions and the maximum value is determined by the initial refractive index distribution of fiber Bragg grating.