相位掩模板干涉场及其对光纤光栅损耗的影响  

Interference Field Behind Phase Mask and Its Influence on the Loss Characteristic in Fiber Bragg Gratings

作　　者：王迪[1,2] 李璇 皮浩洋[1] 杨飞[1] 叶青[1] 蔡海文[1] Wang Di;Li Xuan;Pi Haoyang;Yang Fei;Ye Qing;Cai Haiwen(Shanghai Key Laboratory of All Solid-State Laser and Applied Techniques,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院上海光学精密机械研究所上海市全固态激光器与应用技术重点实验室,上海201800 [2]中国科学院大学,北京100049

出　　处：《光学学报》2018年第8期284-291,共8页Acta Optica Sinica

基　　金：国家自然科学基金(61405212;61377062;61405218;61775225)

摘　　要：理论分析了紫外准分子激光相位掩模法刻写光纤布拉格光栅时相位掩模板干涉场的形式以及对比度特征,并结合干涉光场对比度与光纤光栅折射率调制度的关系,通过实验证明了随着光纤与相位掩模板距离的增加,相位掩模板形成的干涉光场对比度会越来越低,这种对比度的降低导致了光纤布拉格光栅损耗的增加。进一步的分析显示:非±1级衍射能量的增加、紫外光束斜入射角度增加、紫外激光时空相干性的恶化等因素也会导致干涉场对比度降低,因此实验上要尽量避免这些不利因素的影响。该研究结果对高功率FBG刻写装置的光源、相位掩模板的选择以及光路调试等具有重要的指导意义。The ultraviolet interference field behind the phase mask for fabricating fiber Bragg grating（FBG）and the interference contrast are studied.The relationship between the interference contrast of light field and the refractive index modulation of FBG is taken into account in this paper.The experimental results show that increasing the distance between the optical fiber and the phase mask makes the interference contrast decrease.The reduction of interference contrast leads to an increase of loss in FBG.The numerical investigations also demonstrate that the increase of non ±1 order diffraction energy,the deterioration of the time and the spatial coherence of ultraviolet（UV）laser and the increase of oblique incident angle of UV light beam could reduce the interference field contrast.In order to fabricate low-loss fiber gratings,these unfavorable factors must be overcome.The results provide the technical basis for the selection of ultraviolet laser source,phase mask and optical path alignment in the FBG fabrication used in high power fiber lasers.

关 键 词：光纤光学 光纤布拉格光栅 相位掩模板 干涉光场 

分 类 号：TN253[电子电信—物理电子学]