The 975 nm multimode diode lasers with high-order surface Bragg diffraction gratings have been simulated and calculated using the 2D finite difference time domain (FDTD) algorithm and the scattering matrix method (SMM). The periods and etch depth of the grating parameters have been optimized. A board area laser diode (BA-LD) with high-order diffraction gratings has been designed and fabricated. At output powers up to 10.5 W, the measured spectral width of full width at half maximum (FWHM) is less than 0.5 nm. The results demonstrate that the designed high-order surface gratings can effectively narrow the spectral width of multimode semiconductor lasers at high output power.

Frequency modulation (FM)-to-amplitude modulation (AM) conversion is an important factor that affects the time–power curve of inertial confinement fusion (ICF) high-power laser facilities. This conversion can impact uniform compression and increase the risk of damage to optics. However, the dispersive grating used in the smoothing by spectral dispersion technology will introduce a temporal delay and can spatially smooth the target. The combined effect of the dispersive grating and the focusing lens is equivalent to a Gaussian low-pass filter, which is equivalent to 8 GHz bandwidth and can reduce the intensity modulation on the target to below 5% with 0.3 nm @ 3 GHz + 20 GHz spectrum phase modulation. The results play an important role in the testing and evaluating of the FM-to-AM on the final optics and the target, which is beneficial for comprehensively evaluating the load capacity of the facility and isentropic compression experiment for ICF.

Mid-spatial frequency wavefront deformation can be deleterious for the operation of high-energy laser systems. When fluid cooled high-repetition-rate amplifiers are used, the coolant flow is likely to induce such detrimental mid-spatial frequency wavefront deformations. Here, we describe the design and performance of a 90 mm × 90 mm aperture, liquid-cooled Nd:phosphate split-slab laser amplifier pumped by flash-lamps. The performance of the system is evaluated in terms of wavefront aberration and gain at repetition rates down to 1 shot per minute. The results show that this single cooled split-slab system exhibits low wavefront distortions in the medium to large period range, compatible with a focus on target, and despite the use of liquid coolant traversed by both pump and amplified wavelengths. This makes it a potential candidate for applications in large high-energy laser facilities.

The large-aperture pulse compression grating (PCG) is a critical component in generating an ultra-high-intensity, ultra-short-pulse laser; however, the size of the PCG manufactured by transmission holographic exposure is limited to large-scale high-quality materials. The reflective method is a potential way for solving the size limitation, but there is still no successful precedent due to the lack of scientific specifications and advanced processing technology of exposure mirrors. In this paper, an analytical model is developed to clarify the specifications of components, and advanced processing technology is adopted to control the spatial frequency errors. Hereafter, we have successfully fabricated a multilayer dielectric grating of 200 mm × 150 mm by using an off-axis reflective exposure system with Φ300 mm. This demonstration proves that PCGs can be manufactured by using the reflection holographic exposure method and shows the potential for manufacturing the meter-level gratings used in 100 petawatt class high-power lasers.

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。

为实现高功率的蓝光半导体激光输出，对蓝光巴条的封装技术进行了研究。利用金锡硬焊料封装了高功率氮化镓（GaN）蓝光半导体激光巴条，应用铜钨过渡热沉作为缓冲层抑制了铜热沉和GaN激光芯片之间封装残余应力，采用高精度贴片机将芯片共晶键合在铜钨过渡热沉上。贴片质量的好坏直接影响了器件的输出特性，所以重点分析了贴片机的焊接温度焊接压力、焊接时间对器件的影响。实验结果表明：当贴片机的焊接温度为320 ℃、焊接压力为0.5 N、焊接时间为40 s时，焊料层界面空洞最少，热阻最低为0.565 ℃/W，阈值电流最低为4.9 A，在注入电流30 A时，输出光功率最高为32.21 W，最高光电转换效率达到了23.3%。因此，在优化焊接温度、焊接压力、焊接时间后，利用金锡硬焊料将蓝光半导体激光芯片共晶键合在铜钨过渡热沉的技术方案是实现蓝光半导体激光巴条高功率工作的有效途径。