高性能超四面体Tn团簇基红外非线性光学材料的设计合成

通过非线性光学（NLO）晶体的变频效应是实现中远红外激光最为主要的技术手段，限制其高能激光输出的技术瓶颈是缺乏兼具大的NLO系数和高的激光损伤阈值（LIDT）的中远红外NLO晶体材料。为了获得大的NLO效应，传统研究思路是基于多面体单体的结构设计，本项目率先采用硫属超四面体Tn团簇作为NLO功能基元制备红外NLO材料。同时，为了克服经典“硫属超四面体Tn团簇”和“有机阳离子”结构模型中有机基团在红外波段存在化学键吸收的问题，本项目选用离子性强碱（土）金属卤化物盐作为新型平衡阳离子(拓宽带隙进而提高LIDT)，通过构建“硫属超四面体Tn团簇”和“无机阳离子”结构模型的研究思路，开展NLO材料的结构设计与NLO性能的研究；获得2-3例具有大NLO效应和高LIDT的中远红外NLO材料，并揭示Tn团簇结构与NLO性能的关系规律；预期发表高质量论文4-6篇，申请发明专利2-4件，培养研究生2-3名。

The most important approach to produce mid-far infrared (MFIR) laser is based on the frequency conversion effect of nonlinear optic (NLO) crystal. The bottleneck of realizing high power laser output is the lack of MFIR NLO crystal simultaneously exhibiting both large NLO coefficient and high laser damage threshold (LIDT). To pursue large NLO effects, the structural design of polyhedral monomers is traditionally adopted. In this project, we innovatively use chalcogenide supertetrahedral Tn clusters as NLO functional motifs to build IR NLO materials. In order to overcome the problem of chemical bond infrared absorption of organic groups in classical structural model of "chalcogenide Tn cluster" and "organic cations", the innovative structure model of " chalcogenide Tn cluster" and "inorganic cations" will be developed in this project by using ionic alkali (alkali-earth) metal halides as counter cations to increase band gap as well as LIDT. Based on above idea, the structure design and performances of MFIR NLO materials will be studied. Finally, the goal of discovering 2-3 MFIR NLO materials with both large NLO coefficient and high LIDT will be achieved; and the relationship between the structure of Tn clusters and NLO properties will be revealed; Moreover, publishing 4-6 high quality papers, applying 2-4 invention patents, and supervising 2-3 graduate students will be completed.