Transverse stimulated Raman scattering (TSRS) in potassium dihydrogen phosphate (KDP) and deuterated potassium dihydrogen phosphate (DKDP) plates for large-aperture, inertial confinement fusion (ICF)-class laser systems is a well-recognized limitation giving rise to parasitic energy conversion and laser-induced damage. The onset of TSRS is manifested in plates exposed to the ultraviolet section of the beam. TSRS amplification is a coherent process that grows exponentially and is distributed nonuniformly in the crystal and at the crystal surfaces. To understand the growth and spatial distribution of TSRS energy in various configurations, a modeling approach has been developed to simulate the operational conditions relevant to ICF-class laser systems. Specific aspects explored in this work include (i) the behavior of TSRS in large-aperture crystal plates suitable for third-harmonic generation and use as wave plates for polarization control in current-generation ICF-class laser system configurations; (ii) methods, and their limitations, of TSRS suppression and (iii) optimal geometries to guide future designs.

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。

由于金属杂质离子对晶体损伤性质有不容忽视的影响，受实验条件限制，Fe及其团簇缺陷对晶体的影响机制尚不明确。采用第一性原理的方法，对磷酸二氢钾（KDP）和磷酸二氢铵（ADP）晶体中的Fe及其团簇缺陷进行模拟研究，确定其对晶体结构及光学性质方面的影响。研究发现，Fe进入KDP和ADP晶体中主要以取代P原子形成FeO₄基团最稳定，且其稳定形式以Fe³⁺为主。磁性状态研究发现磁性条件对晶体的结构和能量影响不大，Fe对晶体的损伤主要通过引起200～300 nm范围明显的光学吸收影响损伤阈值。Fe进入晶体中形成团簇缺陷可通过电荷补偿与O空位（V_O）复合，几乎不会与OH空位（V_OH）复合，团簇缺陷以Fe对晶体结构和性质的影响为主。

在高功率固体激光装置中，大口径KDP晶体的面形畸变控制是影响终端光学组件倍频转化效率的关键因素之一。为了提高大口径KDP晶体的装配附加面形质量，提出了一种点支撑装配附加面形畸变抑制工艺方法。首先，通过遗传算法对支撑点及其分布进行优化设计。然后，采用有限元分析方法对KDP晶体的装配预紧工艺进行优化设计。最后，开展优化后的装配工艺对KDP晶体装配附加面形畸变的抑制和倍频转换效率的实验验证。实验结果表明：提出的工艺方法对KDP晶体装配附加面形畸变具有良好的抑制效果，实测面形PV值为6.51 μm，二倍频转化效率可达72.6%，且重复装配的一致性良好。该方法大幅提升了晶体倍频效率和远场光斑质量，并在工程上得到应用与推广。

在惯性约束聚变（ICF）领域，为了满足物理实验需求，需要采用短波长的紫外激光打靶。目前，国内外高功率固体激光装置普遍采用谐波转换的方式来获得三倍频紫外激光。高效的频率转换必须满足相位匹配条件，而晶体的反射面形畸变过大对准直精度和倍频效率均匀性都会产生不利影响。通过实验验证了晶体准直光斑的质量退化主要来源于晶体因夹持和重力导致的反射面形畸变，证明了改进晶体的夹持方式可以有效改善晶体面形，提高准直精度和准直光斑质量，并显著提升三倍频转换效率。

To determine whether a potassium dihydrogen phosphate (KDP) surface mitigated by micro-milling would potentially threaten downstream optics, we calculated the light-field modulation based on angular spectrum diffraction theory, and performed a laser damage test on downstream fused silica. The results showed that the downstream light intensification caused by a Gaussian mitigation pit of 800 μm width and 10 μm depth reached a peak value near the KDP rear surface, decreased sharply afterward, and eventually kept stable with the increase in downstream distance. The solved peak value of light intensification exceeded 6 in a range 8–19 mm downstream from the KDP rear surface, which is the most dangerous for downstream optics. Laser damage sites were then induced on the fused silica surface in subsequent laser damage tests. When the distance downstream was greater than 44 mm with a downstream light intensification of less than 3, there were no potential damage threats to downstream optics. The study proves that a mitigated KDP surface can cause laser damage to downstream optical components, to which attention should be paid in an actual application. Through this work, we find that the current manufacturing process and the mitigation index still need to be improved. The research methods and calculation models are also of great reference significance for related studies like optics mitigation and laser damage.