混频KDP晶体内前驱体激光预处理微观机制研究

在ICF高功率激光器中， KDP晶体是目前唯一可选用的非线性晶体材料。由于晶体内前驱体过度吸收，混频KDP晶体在远低于其本征损伤阈值的通量下会出现体损伤，它严重限制了元件的使用寿命、提升了激光器的运行成本以及降低了激光器可靠性。针对混频KDP晶体激光预处理，本项目开展激光预处理参数对晶体体损伤性能影响的研究，探索激光预处理过程中前驱体微观物理特性的变化，在激光辐照参数、前驱体微观物理特性变化和晶体基质材料宏观损伤特性变化三者之间建立联系，并结合现有物理模型深入认识激光预处理机制，进而探索一种有效提高晶体体损伤性能的方法。本项目的研究工作将为理解、控制和提高KDP晶体激光损伤性能提供科学依据和理论指导。

KDP crystals are currently the only available nonlinear materials for ICF (Inertial Confinement Fusion) lasers. Unfortunately, due to the excessive absorption of laser energy by precursors located in bulk materials, the laser-induced-bulk-damage of tripler KDP crystal optics at fluence far below the intrinsic damage threshold dramatically limits the lifetime of crystal optics itself, increases laser system maintenance costs, and decreases laser system reliability. In order to elucidate the micro-mechanisms of laser conditioning, this project attempts to investigate the influence of laser conditioning parameters on bulk damage resistance of KDP crystal, study the change of microcosmic characteristics of precursors, and then uncover the underlying relationship among the laser conditioning parameters, microcosmic characteristics of precursors, and bulk damage resistance of KDP crystal. Finally, an effect method to improve bulk damage resistance can be explored by optimizing the laser conditioning parameters based on machine learning method. This work would be significant for providing technical advancements and theoretical supports to elucidate, mitigate, and improve bulk damage resistance of KDP crystals.