热诱导KDP晶体应力缺陷演化规律的超微观研究

The strain defects of KDP crystals induced by thermal effects of laser irradiation reduce the laser damage threshold and harmonic generation capability. It becomes very important to deeply understand the super-microstructure of strain defects of KDP crystals at atomic-scale, which is important to investigating the mechanism of absorption, accumulation and thermal transformation process of laser energy inside KDP crystal and is urgently needed in this field. To solve the above scientific issues, this project aims at establishing and developing a set of efficient characterization techniques based on advanced transmission electron microscope (TEM) techniques for strain defects of KDP crystal. Characterization methods targeting different types of KDP defects would be established. The physical essence of the influences of strain defects of KDP crystals on the harmonic generation power/photoelectric effect will be illustrated. From the super-microstructure point of view, the influence mechanism of the strain defects of KDP crystals, such as dislocation-related defects and impurity metallic ions, on the laser harmonic generation and photoelectric capability of KDP crystals will be studied. Based on the combined advanced TEM techniques, including in situ TEM heating, 3D-tomography reconstruction, electron energy loss spectroscopy and electron holography, the formation mechanism and evolution law of strain micro-defects induced by thermal effects of laser will be comprehensively investigated. Moreover, the atomic structure and the chemical composition and bonding information of impurity metallic ions would be studied in detail. The dependences of the types, quantity and density of defects of KDP crystals on the device performance of KDP crystals would be emphasized.

激光热诱导产生的KDP晶体应力缺陷降低了激光损伤阈值和谐波转化能力。在原子层次深入理解KDP晶体中的应力缺陷的超微观结构，对于研究激光能量在KDP晶体中的吸收、累积和热转化机理十分重要，且是目前本领域急需的。为解决以上科学问题，本课题旨在探索发展一套对KDP晶体应力缺陷有效的、基于先进透射电镜技术的探测表征技术，并提出针对不同类型缺陷的表征方法。阐明KDP晶体应力缺陷影响谐波转换/光电性能的物理本质。从超微观结构本质出发，研究热诱导KDP晶体中微观应力缺陷，如位错等结构缺陷和杂质金属离子，对激光倍频输出、光电开关等功能器件的影响机制。综合利用基于透射电子显微学的各类先进技术：原位加热、三维重构、电子能量损失谱、电子全息，研究重频激光作用下KDP晶体中热应力微观缺陷的形成机制。深入研究缺陷的原子结构和杂质金属离子的化学成分及键合信息，尤其是缺陷类型、数量与密度对KDP晶体器件性能的演化规律。

按照任务书规定的内容执行。1、针对KDP晶体应力缺陷与显微结构，发展了一套于先进透射电镜技术的基探测表征技术，并建立了适用于不同类型缺陷的表征方法，主要包括在低温下的高分辨结构图像学、电子能量损失谱谱学分析、电子衍射、暗场衍衬成像、高分辨成像与高角环形暗场像等技术。2、从超微观结构本质出发，研究热诱导KDP晶体中微观应力缺陷，如位错等结构缺陷和杂质金属离子，对激光倍频输出、光电开关等功能器件的影响机制。综合利用基于透射电子显微学的各类先进技术：原位加热、三维重构、电子能量损失谱、电子全息，研究重频激光作用下KDP晶体中热应力微观缺陷的形成机制。3、基于透射电子显微学和其他分析手段，，发现了KDP晶体棱柱状析出的各向异性依赖性。系统研究了结构缺陷在KDP晶体在激光辐照过程中的稳定性。共发表标注课题号的论文35篇，含自然通讯1篇、美国科学院院刊1篇、先进材料2篇。