含阳离子基团中远红外非线性光学晶体材料的结构设计及性能强化

通过非线性光学（NLO）晶体的变频效应获得中远红外激光在军事和民用领域具有重要的应用。同时具有大的NLO系数和高的激光损伤阈值（LDT）的NLO晶体材料是实现高功率激光的关键。传统中远红外NLO晶体的结构模型通常为“简单阳离子”和“阴离子基团”，注重对阴离子基团的结构设计以提升NLO系数，该结构模型中能满足兼具大NLO系数和高LDT要求的材料极少。本项目创新性地提出以强离子性的碱（土）金属卤化物盐为“阳离子基团”（拓宽带隙进而提高LDT），以共价性的金属硫属化合物为“阴离子基团”（增强NLO效应），采用双功能基元协同构筑新材料的研究思路，开展高性能中远红外NLO材料的结构设计、可控制备、NLO效应及LDT等性能研究；获得2-3个具有应用前景的中远红外NLO新晶态材料；并揭示功能基元的结构特征及其与NLO性能的关系规律；预期发表高质量论文6-8篇，申请发明专利4-6件，培养研究生3-5名。

Nonlinear optical (NLO) crystals can produce mid-far infrared (MFIR) lasers based on their frequency conversion capbility, which are widely applied in the national defense and civil applications. A NLO crystal material that simultaneously possesses large NLO properties and high laser-induced damage threshold (LDT) is crucial to generate high power laser. The general structure model of traditional MFIR NLO materials contains "simple cation" and "anion group". It is mainly focused on the structure design of anion group to improve the NLO coefficient, and few of those meets the requirements of both large NLO coefficient and high LDT. In this project, we propose the new idea that the ionic alkali (or earth-alkali) metal halide salt serve as "cationic group" to broad bandgap and to improve LDT, and covalent metal chalcogenide serve as "anionic group" to increase NLO intensity, and the double functional motifs are assembled together to synergistically construct new materials. Then the synthesis, structure, NLO and laser damage performances of these NLO materials will be intensively investigated. Finally, the goal of discovering 2-3 promising MFIR NLO material candidates and revealing the relationships between their structural characteristics and NLO properties will be achieved. Moreover, publishing 6-8 high quality papers, applying for 4-6 patents and supervising 3-5 graduate students will be completed.