采用多层相屏法和快速傅里叶变换法数值求解热晕方程，研究了复合贝塞尔高斯（cBG）光束大气传输过程中受热晕效应的影响。研究发现：由于热晕效应造成的光强和相位畸变，cBG光束会发生相位奇点移动和轨道角动量谱展宽，并产生模式串扰。当风速较小时，大气介质吸收激光产生的热效应较强，导致光束的模式串扰也较强。对于初始角量子数差值较大的cBG光束，其相对串扰能量较小，受热晕效应影响导致的模式串扰较弱。此外，还研究了旋转cBG光束的热晕效应，该光束的旋转特性使其在传输过程中四周都能得到均匀的扩展。因此，相较于非旋转cBG光束，旋转cBG光束的光强分布比更均匀，模式串扰更小。并且，随着旋转cBG光束的径向波数差值的增大，模式串扰减弱。综上，增大初始角量子数差值以及径向波数差值可以有效降低cBG光束的模式串扰。

提出了一种基于1064 nm掺镱光纤激光器泵浦MgO:PPLN的3.83 μm中红外光学参量振荡器。基于单谐振光学参量振荡器的阈值理论和线宽压窄前后的光束能量集中性理论，分析了不同泵浦光束聚焦深度下，谐振腔内光束分布情况以及线宽调制前后能量的不同集中程度对阈值和光-光转换效率所产生的影响。通过采用单个光纤布拉格光栅的方式压窄了泵浦光线宽，对比分析了在不同占空比下，泵浦光线宽压窄前后对中红外光学参量振荡器输出特性的影响。当泵浦功率为18 W，脉冲激光占空比为0.2%，脉宽为100 ns，泵浦光线宽为2.5 nm时，MgO:PPLN中红外光学参量振荡器获得功率为1.42 W的3.83 μm激光输出，光-光转换效率为7.9%。将线宽压窄到0.1 nm后，脉宽为2 ns，MgO:PPLN中红外光学参量振荡器获得最高功率为1.98 W的3.83 μm激光输出，光-光转换效率为11%，光束质量M²=1.89；同时相比于线宽压窄前激光输出效率提高了39.2%。

A continuous-wave (CW) π-polarized 1084 nm laser based on Nd:MgO:LiNbO3 under 888 nm thermally boosted pumping is reported. According to the absorption spectrum and energy level structure of Nd:MgO:LiNbO3, the 888 nm laser diode (LD) is used for thermally boosted pumping. This pumping method eliminates the quantum defect caused by the nonradiative transition in Nd:MgO:LiNbO3 under the traditional 813 nm pumping and effectively improves the serious thermal effect of the crystal. The unmatched polarized 1093 nm laser is completely suppressed, and the π-polarized laser output of 1084 nm in the whole pump range is realized by the 888 nm thermally boosted pumping. In the present work, we achieved the CW π-polarized 1084 nm laser with a maximum output power of 7.53 W and a slope efficiency of about 46.1%.

采用放大1064 nm掺镱光纤激光器作为泵浦源，实现了中红外3.8 μm MgO:PPLN 光参量振荡（OPO）激光输出。在泵浦源中，采用分布式反馈激光器（DFB）作为种子源来实现光纤激光窄线宽的调制，实现线宽2.5 nm到0.1 nm的压缩，最大平均输出功率可达40 W。进一步对不同泵浦线宽条件下中红外3.8 μm MgO:PPLN OPO激光进行研究，最终在泵浦功率为18.1 W、线宽为0.1 nm、重频为1 MHz、脉宽为2 ns时，获得了最高平均输出功率为2.06 W的3822.5 nm激光输出，光-光转换效率为11.38%，光束质量为M²=2.34，提高了窄线宽泵浦对中红外MgO:PPLN OPO激光输出效率。

We demonstrate a three-nanosecond equidistant sub-pulse multi-step Q-switched Nd:Y₃Al₅O₁₂ (Nd:YAG) laser. In the time interval of 100–1000 ns, three pulses with the same nanosecond interval and the same peak power are obtained at the pulse width of 24 ns, 28 ns, and 36.6 ns, respectively. The energy is 32.5 mJ, and the optical efficiency is 10.8%. The multi-step Q-switched method does not require the insertion of other optical elements into the traditional Q-switched laser, and it is very suitable to obtain pulse group output with several nanosecond pulse intervals.

We examined a 1514 nm eye-safe passively Q-switched self-optical parametric oscillator. The nonlinear crystal is an a-cut Nd:MgO:PPLN crystal, and the size of the crystal was 6 mm × 2 mm × 30 mm with 0.4 at.% Nd³⁺ doped and a grating period of 29.8 μm. When the crystal absorbed 12.8 W, the output maximum single-pulse energy reached 39 μJ, and a pulse width of 6.1 ns at a repetition rate of 5.4 kHz was obtained. The peak power was 6 kW, giving a slope efficiency of 42%.