精密高效的脉冲波形调控是大型激光装置满足惯性约束聚变实验需求的重要技术之一。脉冲波形生成原理是通过编辑任意波形发生器中每个子脉冲的电压值，经电光调制器转换为光脉冲强度形成任意形状的激光脉冲轮廓。在电光转换过程中，各子束响应过程并非线性且子束间存在个性差异。为实现此条件下精密高效的脉冲波形调控，制定并开发了基于闭环迭代思路的激光脉冲波形快速调控方法。实验结果表明，算法可在10 min内实现任意脉冲波形整形，并具备23∶1高对比度脉冲波形调控能力，调控精度均优于10% (rms)，满足常规物理实验运行条件下对激光参数调控的精度和效率需求。

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。

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.

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.

The generation and measurement of complex ultraviolet laser pulse shapes is demonstrated in the SG-III laser facility. Relatively high contrast ratio of 300∶1 required by the physics experiment is achieved and successfully measured. Two continuous main shots validate the reproduction and the stability of the pulse shape, which provide solid foundation for precise physics experiment and laser power balance.