高功率固体激光装置的负载问题是制约装置建设与运行的瓶颈问题。在高通量紫外纳秒激光辐照下，熔石英后表面的损伤不断产生和增长，严重限制了装置的负载能力。在提升熔石英抗损伤性能的基础上修复既有损伤，循环使用光学元件，是现阶段提升装置负载能力的主要手段。主要介绍了国内外近年来在熔石英损伤的规律与机制、光学元件循环处理的支撑技术以及提升负载能力的新材料与新技术方面所取得的重要进展。

针对高速流场下凸台周围的气动光学效应，对不同马赫数下的三种凸台形状周围的流场进行仿真计算，计算得到流场的密度变化，计算了光线经流场传输后的光程差。仿真结果表明：随马赫数增大，光程差逐步增大；同等条件下，不同出射角度对应的光程差不同，凸台存在强烈的尾流区域，从而导致较大的光程差；在马赫数达到跨音速时，凸台顶端也会产生较大的光程差；曲率较小的凸台结构对周围流场的影响较小。

高功率固体激光装置对大口径反射镜附加波前畸变和姿态稳定提出了苛刻的要求，在确保姿态稳定性的同时，要求低应力夹持使附加波前畸变峰谷值（PV值）＜λ/3, 波长λ=633 nm。提出了一种正面三点支撑结合侧面八点限位的大口径反射镜夹持技术，对该夹持结构下引起的附加波前畸变进行了仿真和实验研究，并对反射镜姿态稳定性进行了不同工况下的实验模拟。结果表明，该夹持方式引入的附加波前畸变PV值约为23.6 nm，振动、晃动、翻转不同工况下反射镜指向变化PV值小于50 μrad，附加波前畸变和姿态稳定性均满足高功率激光装置的要求。

At the surfaces of crystals, linear susceptibility tensors would differ from their counterparts in the interior of the bulk crystal. However, this phenomenon has not been shown in a visible way yet. In previous researches, numerous types of nonlinear Cherenkov radiation based on different materials have been studied, while linear Cherenkov radiation is barely reported. We experimentally prove the generation of linear Cherenkov radiation on the potassium dihydrogen phosphate (KDP) crystal surface and theoretically analyze its phase-matching scheme. In our study, o-polarized light and e-polarized light can mutually convert through the linear Cherenkov process. According to this result, we figure out new nonzero elements at off-diagonal positions in the linear susceptibility tensor matrix at crystal surfaces, compared with the normal form of a bulk KDP.

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。

光束精密调控是惯性约束聚变(ICF)研究对激光驱动器的基本需求，它是一项装置层面的系统工程。主要介绍了中国工程物理研究院激光聚变研究中心近年来在靶面光强控制、脉冲波形控制、光束近场控制以及在新型光束探索方面所取得的重要进展。

对于采用离轴多程放大技术的高功率激光装置，抑制其自激振荡的技术具有重大研究价值。针对工程中发现的主放大系统小孔板附近结构表面比较光亮，当腔内放大器工作时，在增益足够条件下，光亮结构面和腔镜间形成谐振腔而产生自激振荡，烧蚀腔内器件的问题，基于蒙特卡洛方法模拟结构表面，依据几何光学原理推导了激光光束在结构表面反射模型，采用该模型代入工程中光路部分参数计算了主放大系统结构表面粗糙处理工艺和反射进入放大器内份额的关系，并将该表面处理工艺应用于工程中，通过增大结构表面粗糙度，使形成的谐振腔损耗大于增益，为抑制高功率激光装置主放大系统自激振荡提供了依据。

Fifth harmonic generation (5th HG) of a Nd:glass laser is an effective way to acquire high-energy coherent deep-ultraviolet radiation near 200 nm. In this work, cascade generation of the fifth harmonic of a Nd:glass laser in a 5 mm ammonium dihydrogen phosphate (ADP) crystal was investigated, and maximum conversion efficiency of 14% and large angular acceptance of 45 mrad were demonstrated at a noncritical phase-matching temperature of 75.1°C. However, as the results reveal, the temperature sensitivity and nonlinear absorption would hinder its high-energy application. As for that, based on the complementary relationship of the angle and temperature in the phase-matching condition, an upgraded focusing 5th HG design coupled with the cylindrical temperature distribution scheme was proposed. By this upgraded focusing design, more than the improvement of the conversion efficiency, the output 5ω near-field intensity distribution turns out to be insensitive to the temperature gradient. Potentially, this idea can be applied for many other frequency conversion schemes such as high-repetition frequency lasers, which have similar temperature gradient problems.

Collinear phase-matching of sum-frequency generation (SFG) has been studied thoroughly previously, while non-collinear schemes are sometimes more flexible in application. However, this phase-matching type is more difficult to meet and control. We employ a convenient method to obtain harmonic generation in bulk potassium dihydrogen phosphate (KDP), using an incident wave vector and a reflected wave vector to create a triangle phase-matching relationship. With a simple, flexible set-up, we can observe 351 nm SFG, and the conversion efficiency is up to ～3.6% per reflection. Furthermore, we believe this approach has potential application value and improvement space.

Stray light in high-power laser facilities not only decreases the gain capacity of the main amplifier, but can also cause permanent damage to optical components, greatly threatening the safety operation of the SG-III. This Letter reports a technique for quickly pinpointing the source of stray light in the main amplification optical path of the SG-III. The achieved results indicate that the accuracy of our method is up to 1 m in an optical path of 100 m. The judging method is effective for examining and removing harmful stray light in the SG-III laser facility and it can be promoted in huge laser facilities of this kind.