紫外脉冲激光退火发次对KDP晶体抗损伤性能的影响

在R-on-1的辐照模式下, 利用355 nm的紫外脉冲激光以低于KH₂PO₄ (KDP)晶体零概率损伤阈值的通量对其进行不同发次的全域扫描, 目的是为了研究KDP晶体在接受不同发次的紫外激光辐照后其抗损伤能力的变化规律及机制. 辐照后的1-on-1损伤测试表明, 适当的紫外激光退火可以有效地提升KDP晶体的抗损伤能力, 提升的幅度与其接受激光扫描的次数有关. 通过荧光和紫外吸收检测深入探讨了晶体内缺陷对激光退火的影响, 结果表明: 紫外脉冲激光辐照后KDP 晶体内的氧空位电子缺陷的存在与否是导致其抗损伤能力变化的主要原因; 通过拉曼和红外光谱的测量表明, 辐照后KDP 晶体内的PO₄, P–OH和P＝O基团的极化变形也导致了其抗损伤能力的改变. 关键词： 激光退火 荧光 拉曼 红外

Effect of raster scan number on damage resistance of KDP crystal irradiated by ultraviolet pulse laser

The raster scanning experiments for KDP crystal are carried out in R-on-1 mode at energy density below zero probability damage threshold to investigate the damage resistance capability as a function of pulse number after ultraviolet (UV) laser irradiation by using a tripled Nd:YAG laser. The1-on-1 damage measurements after laser irradiation indicate that the damage resistance of KDP is obviously enhanced and the increment is dependent on scanning number. The optical absorption and photoluminescence spectra show that the evolution of oxygen-vacancy centers in KDP crystal is important to the damage resistance capability. The Raman and infrared spectra show that the polarization distortions of PO₄, P–OH and P＝O groups induced by UV laser irradiation also contribute to the changes of damage resistance.
Keywords： laser conditioning fluorescence Raman spectra infrared spectra