KDP类晶体的激光损伤研究

Laser damage of KDP crystals and their analogues

KDP类晶体是唯一可以满足ICF激光驱动装置通光口径的非线性光学晶体材料。该类晶体采用水溶液生长法生长,易于产生宏观包裹体和微观晶格缺陷,在高功率激光辐照下晶体内部易产生高密度pinpoint损伤现象,这与其他方法生长的晶体只是受限于光学加工的表面损伤问题相比具有明显不同。KDP类晶体内部的缺陷或前驱体诱导激光损伤与晶体切向、激光波长及偏振方向等密切相关,使得应用于ICF激光驱动器中不同光学功能的、来源于同一晶坯的不同晶体元件也表现出损伤性能的差异性,因此其损伤机理非常复杂,迫切需要认识该类晶体的激光损伤机理问题。回顾了上海光学精密机械研究所联合福建物质结构研究所、山东大学等晶体研制单位联合开展的关于KDP类晶体激光诱导损伤特性的研究工作,进行了用于光开关、倍频以及混频等功能的KDP和不同氘含量DKDP晶体的激光损伤研究,指导了晶体生长工艺优化和过程关键因素控制,并对仍存在的问题及解决方案进行了展望,对于高性能KDP类晶体的研制以及在高功率激光系统中的合理应用具有参考价值。

KDP-family crystals are the only nonlinear optical crystal material according with the opticalaperture of ICF laser drivers.As KDP-family crystals are grown by aqueous solution method,the macroscopicinclusions and microscopic lattice defects easily occur in the bulk of the crystals.The high density pinpoints damagephenomenon appears as they are irradiated by the high power laser.All the laser induced damage properties aredifferent from the surface damage of crystals grown by other methods,which are only limited by optical processing.The laser induced damage by defects or precursors are related to the laser wavelengths and even the laser polarizationdirection,and the different samples from the same as-grown single crystal and applied to different optical functions inICF laser drivers show different laser induced damage properties.Therefore,the damage mechanism is verycomplicated,and it is urgent to know the laser induced damage mechanism of KDP-family crystals.In this paper,thecooperated research of Shanghai Institute of Optics and Mechanics with Fujian Institute of Research on the Structureof Matter,Shandong University and other crystal research institutes is reviewed.The laser induced damage propertiesof KDP and DKDP crystals applied as optical switching,frequency doubling and frequency mixing optical elementswere investigated.The optimization of crystal growth process and the control of key factors were guided and theexisting problems and solutions were prospected.The research has reference value for the development of high-performance KDP-family crystals and their rational application in high-power laser systems.