基于硫系玻璃(As2S3)光纤的光敏性及其应用于写Bragg光栅的研究

硫系玻璃具有优良红外透光性和极高光学非线性，其光子器件在近中红外波段有广泛应用前景。光敏性是硫系玻璃现象之一，研究其特性及应用以前主要集中在薄膜结构上。在我们工作中初步发现硫系玻璃光纤结构与薄膜结构的光敏性存在显著差异。因此，拟提出详细研究硫系玻璃光纤光敏性，并利用其深入研究制备硫系玻璃光纤的Bragg光栅。本项目主要包括数值分析不同波长光侧向照射As2S3硫系玻璃光纤的光能量横向分布；基于法布里-珀罗标准具和回音壁模式原理，实验研究As2S3硫系玻璃阶跃型光纤和微光纤的光致折射率变化，厘清其光敏性，提出光诱导动力模型；采用改进型Sagnac干涉仪组成的光栅写入系统，研究制备高反射率、光谱质量良好的As2S3硫系玻璃光纤Bragg光栅，并结合实验，理论分析包层和芯层都具有光敏性的硫系玻璃光纤的光栅形成特征。这些工作将深入梳理硫系玻璃不同体结构下的光敏性，为制备其光子器件提供新思路。

Chalcogenide glasses (ChGs) possess excellent transparency in infrared region and high optical nonlinear, so their photonic devices have broad application prospects in near- and mid-infrared spectral region. Photosensitivity is one of the phenomena of ChGs, so far it is focused on film samples for studying its characteristics and applications.In ours work, preliminary analysis indicates that there are significant differences about ChGs' Photosensitivity in fiber structure and film structure. Therefore, we propose a project of detailed study on photosensitivity in chalcogenide glass fiber, and then inscription of Bragg grating in chalcogenide glass fiber by this photosensitivity. This project includes: Under side illumination,the lateral distribution of light energy dependence on wavelengths insde As2S3 chalcogenide glass fiber is numerically analyzed; For clarifying their photosensitivity, photoinduced refractive index changes in As2S3-based step index fiber and microfiber are studied by use of Fabry-Perot etalon and whispering gallery mode principle respectively, and then a photoinduced dynamic model is proposed; Inscription of Bragg grating with high reflectivity and good quality spectrum in As2S3 chalcogenide glass fiber is studied using a modified Sagnac interferometer grating writing system, and formation feature of grating in chalcogenide glass fiber is theoretically studied due to the fact that the core and cladding in chalcogenide glass fiber have photosensitivity. These works will further understand the photosensitivity of chalcogenide glass in different body structures, and offer a new idea for preparation of ChGs-based photonic devices.