A high-power CW Yb:YAG slab laser amplifier with no adaptive optics correction has been experimentally established. At room temperature, the amplifier emits a power of 22 kW with an average beam quality (β) of less than 3 in 0.5 min. To our knowledge, this is the brightest slab laser without closed-loop adaptive optics demonstrated to date. In addition, an extracted power of 17 kW with an optical extraction efficiency of 33%, corresponding to a residual optical path difference of less than 0.5 µm, is achieved with the single Yb:YAG slab gain module. The slab gain module has the potential to be scalable to higher powers while maintaining good beam quality. This makes a high-power solid-state laser system simpler and more robust.

中红外激光领域广泛使用高性能高反射光学元件，高反射率高精度测试技术是制备高性能反射光学元件的基础。针对2.7～3.0 μm波段光学元件高反射率测量的实际需求，基于量子级联激光器建立了连续光腔衰荡反射率测试实验装置，通过优选2.7～3.0 μm波段反射带内水汽吸收较弱的测试波长，分析空气中水汽吸收对衰荡时间和反射率测量的影响，并比较空气和氮气环境下反射率测量结果，实现了2.7～3.0 μm波段高反镜反射率的准确测量，在反射率约99.95%时绝对测量精度优于2×10⁻⁵。实验结果显示，采用测试波长2.9 μm并在测量时保证初始腔和测试腔腔长相同，无需使用氮气环境，直接在实验室空气环境可实现高反射率的精确测量。

针对目前光束质量分析仪只能用于小口径、低功率激光器光束质量评估的问题，开展了高功率激光器光束质量测量的衰减缩束技术实验研究，搭建了缩束激光的波像差及光束质量测量装置，开展了缩束组件装调误差对光束质量影响的实验。实验结果表明，随着装调视场角度的增加，1/3倍缩束组件在1.2°视场处M2测量偏差小于5%。搭建了偏振分光装置，研究了衰减组件对光束稳定性的影响。实验结果表明，随机偏振的准单模激光器的稳定性比多模激光更易受到衰减组件退偏的影响。搭建了高反式与楔板式高功率激光光束质量测量装置，对1 kW准单模激光进行光束质量测量。实验结果表明，在高反式测量装置中，待测光束通过高反镜时产生了退偏，从而导致光束质量测量结果偏小，楔板式测量装置的测量结果更能准确反映待测光的光束质量。

Four-channel off-axis holography is proposed to simultaneously understand the polarization states and the mode coefficients of linearly polarized (LP) modes in few-mode fiber. Far-field off-axis holograms in the four polarization directions of the fiber laser were acquired at the same moment through a four-channel holographic device. The weights, the relative phase differences, and the polarization parameters of the vector fiber laser mode can be solved simultaneously. The simulated and experimental mode analysis of the laser output by 1060-XP fiber with 6 LP modes at 632.8 nm is conducted, which shows that the similarity of the total intensity distribution of the laser before and after mode analysis is above 0.97. The mode polarization states, the mode weights, and the relative phase differences of the few-mode laser can be determined simultaneously in a single shot by four-channel off-axis holography.

Real-time monitoring of wavelength is important for high-speed wavelength phase-shifting interferometry. In this paper, a wavelength sensor based on a polarization-maintaining fiber interferometer with four-quadrant demodulation was proposed. We built the wavelength sensing system with resolution better than 0.005 pm and 0.1 ms sampling interval and measured the response time of the tuned wavelength at 35 ms in the phase-shifting process of a commercial wavelength phase-shifting free-space interferometer, as well as the wavelength drift velocity of 0.01 pm per second in the hysteresis process. The optical fiber wavelength sensor with four-quadrant demodulation provides a real-time wavelength sensing scheme for high-speed wavelength phase-shifting interferometers.

目前光纤光栅在高功率连续光纤激光器中的应用主要有两个方面，一是作为谐振腔腔镜，二是用来抑制激光器的非线性效应。首先论述了光纤光栅作为腔镜技术的发展现状，然后着重论述了能够抑制光纤激光器中非线性效应的特殊光纤光栅的发展状况。并详细描述了倾斜布拉格光纤光栅抑制受激拉曼散射和受激布里渊散射、长周期光纤光栅抑制受激拉曼散射以及相移长周期光纤光栅抑制自相位调制或四波混频等非线性效应引起的光谱展宽的研究进展。最后展望了光纤光栅在高功率光纤激光器领域的发展趋势，认为光纤光栅将朝着更高承载功率与长波长方向发展，同时认为基于飞秒激光刻写的光纤光栅技术、能够同时抑制多种非线性效应的光纤光栅技术、以及基于光纤光栅的光纤激光器激光偏振控制技术等将成为新的研究热点。

激光光闸可以将光纤激光器输出的单束激光通过多通道输出，实现激光器的“一机多用”，是现代化激光智能制造的关键性器件。由于光闸承载功率高达上万瓦，其耦合系统极易产生热效应，影响光闸使用性能。为解决万瓦级激光光闸热效应有效控制的难题，保证光闸的高效耦合与高质量光束输出，采用有限元分析法研究了光闸耦合系统的热效应物理机制，并提出一种基于水循环绕流冷却对光闸耦合系统进行热量管控的新方法。通过万瓦激光下的一系列实验验证，表明文中提出的热效应处理方法保证下，高功率激光光闸能长时间承载万瓦级功率，并保持98%以上的耦合效率，同时抑制了系统的热像差，保证了光闸输出激光的光束质量稳定性。该研究为高功率激光系统的热效应分析及处理提供了有效的手段。

为了实现高功率光纤激光的窄线宽输出，研究了基于大模场三包层掺镱光纤（LMA-YTF）高功率窄线宽光纤激光的热效应和四波混频(FWM)效应。基于FWM效应模型，仿真分析了大模场三包层光纤(LMA-TCF)放大器光谱展宽的影响因素。建立了LMA-YTF的热分布模型，分析了大模场三包层光纤(LMA-YTF)中第二包层功率占比对光纤温度以及泵浦功率上限的影响，讨论了聚合物涂层导热系数和外部温度对光纤温度的影响，实验对比了不同反向合束器的泵浦功率上限，结果表明第二包层功率占比低的(6+1)×1合束器比(9+1)×1合束器拥有更高的泵浦功率上限。基于全国产化器件搭建了一台三包层光纤激光器，实现了输出功率6.7 kW、3 dB线宽为0.32 nm的激光输出。