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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。
The mechanism and rule of refractive index change of hydrogen-doped fiber Bragg grating induced by multiple exposure were studied. Based on the photosensitive model of two-step method, the change of refractive index of multi-exposure-loaded hydrogen-doped fiber grating was analyzed. The relationship between the increase of multiple exposure and the refractive index of grating under different initial refractive index distributions was obtained. The average deflection and modulation of fiber grating The mathematical model of the variation of variables was studied. The wavelength and reflectivity of Bragg grating during multiple exposure were studied by 193 nm ultraviolet laser experiment. The results show that the red shift and the red shift of the center wavelength of the grating under multiple exposure are related to the conditions of re-exposure. The grating reflectance first increases and then stabilizes. The growth rate of reflectance is related to the condition of re-exposure. The initial exposure distribution decision.