A fully automatic fail-safe beam shaping system based on a liquid crystal on a silicon spatial light modulator has been implemented in the high-energy kilowatt-average-power nanosecond laser system Bivoj. The shaping system corrects for gain nonuniformity and wavefront aberrations of the front-end of the system. The beam intensity profile and the wavefront at the output of the front-end were successfully improved by shaping. The beam homogeneity defined by the beam quality parameters was improved two to three times. The root-mean-square value of the wavefront was improved more than 10 times. Consequently, the shaped beam from the second preamplifier led to improvement of the beam profile at the output of the first main cryo-amplifier. The shaping system is also capable of creating nonordinary beam shapes, imprinting cross-references into the beam, or masking certain parts of the beam.

A high-power all polarization-maintaining (PM) chirped pulse amplification (CPA) system operating in the 2.0 μm range is experimentally demonstrated. Large mode area (LMA) thulium-doped fiber (TDF) with a core/cladding diameter of 25/400 μm is employed to construct the main amplifier. Through dedicated coiling and cooling of the LMA-TDF to manage the loss of the higher order mode and thermal effect, a maximum average power of 314 W with a slope efficiency of 52% and polarization extinction ratio of 20 dB is realized. The pulse duration is compressed to 283 fs with a grating pair, corresponding to a calculated peak power of 10.8 MW, considering the compression efficiency of 88% and the estimated Strehl ratio of 89%. Moreover, through characterizing the noise properties of the laser, an integrated relative intensity noise of 0.11% at 100 Hz-1 MHz is obtained at the maximum output power, whereas the laser timing jitter is degraded by the final amplifier from 318 to 410 fs at an integration frequency of 5 kHz to 1 MHz, owing to the self-phase modulation effect-induced spectrum broadening. The root-mean-square of long-term power fluctuation is tested to be 0.6%, verifying the good stability of the laser operation. To the best of our knowledge, this is the highest average power of an ultrafast laser realized from an all-PM-fiber TDF-CPA system ever reported.

We report on frequency doubling of high-energy, high repetition rate ns pulses from a cryogenically gas cooled multi-slab ytterbium-doped yttrium aluminum garnet laser system, Bivoj/DiPOLE, using a type-I phase matched lithium triborate crystal. We achieved conversion to 515 nm with energy of 95 J at repetition rate of 10 Hz and conversion efficiency of 79%. High conversion efficiency was achieved due to successful depolarization compensation of the fundamental input beam.

掺镱全光纤纳秒脉冲激光器发展迅猛，已经为诸多领域开辟了新的道路，特别是高平均功率、大脉冲能量的纳秒脉冲光纤激光器在激光清洗等领域得到了广泛应用。多路光纤激光合束是实现高平均功率、大脉冲能量激光输出的主要手段，其结构复杂程度取决于单模块激光器的输出特性，提升单模块纳秒脉冲全光纤激光器输出特性对于激光清洗等领域具有重要意义。文中总结了单模块掺镱全光纤纳秒脉冲激光器的研究进展，分析了当前限制其功率和能量进一步提升的主要因素。首先，从主动调Q、被动调Q以及增益开关技术三个层面回顾了纳秒脉冲掺镱全光纤振荡器的研究进展；其次，从大脉冲能量、高平均功率、两者协同发展三个指标层面总结了纳秒脉冲掺镱全光纤放大器的研究现状；最后，从限制高指标掺镱全光纤激光器输出特性的因素出发，展望了其在未来功率和能量提升上的发展趋势。

高能激光广泛应用于材料加工、科学研究、空间碎片清除、**应用等领域。二极管泵浦高能激光具有结构紧凑，系统简单、全电驱无限弹仓的特点，近年来，各类二极管泵浦高能激光围绕着同时实现高功率、高效率、高光束质量这一总目标发展迅速。详细综述了国内外高平均功率块状固体激光、高功率可见光波段激光、高峰值功率激光、高功率光纤激光、碱金属蒸气激光等二极管泵浦高能激光的研究进展，并对其发展趋势进行了展望。

高功率、窄脉宽的超快激光在基础科学研究、精密制造和生物医学等领域扮演着越来越重要的角色。在众多飞秒光源中，激光二极管泵浦的掺镱全固态飞秒激光器具有输出特性优异、结构紧凑、简单可靠、成本低廉等优点，成为超快激光领域的研究热点之一。特别是克尔透镜锁模的掺镱全固态飞秒激光器，有望兼备同时输出百瓦级平均功率、百飞秒级脉冲宽度的能力。本文总结了近年来克尔透镜锁模掺镱块材料全固态激光器在高功率窄脉冲输出方面的研究成果，并对实现百瓦级平均功率、十微焦级脉冲能量和高功率GHz重复频率运转给出了展望和方案设想。

介绍一种新型超宽带（相对带宽≥17%）S波段大功率多注速调管的研制过程及研制成果，该速调管首次在S波段实现了17%的相对带宽，带宽指标为国内宽带多注速调管首次实现。通过优化电子光学系统和高频段的参数设计、优化电子枪区的结构设计、优化整管散热系统设计等多项措施，提高电子注流通率及注波互作用效率，降低高频部分的散热压力，使该速调管仅在120 kW的峰值功率下实现了大于30%的效率及40 kW的平均功率。同时，通过近似连续波阴极发射电流密度的低阴极负荷设计、阴极区零部件多项预处理工艺措施等实现了3 ms脉宽的稳定工作及连续24 h稳定工作不打火。为实现3 min内满功率输出及2000 h的寿命，对阴极工作参数、电子枪区的工艺结构进行了反复优化。本项目在能够实现指标的前提下，进行了小批量的生产及车载环境的环境试验，并针对可能产生的不可靠性因素，进行了改进，使产品真正能实现工程化应用，为后续同类产品的设计提供有效的技术参考。