The eXawatt Center for Extreme Light Studies project aimed to create a large scientific infrastructure based on lasers with giant peak power. The project relies on the significant progress achieved in the last decade. The planned infrastructure will incorporate a unique light source with a pulse power of 600 PW using optical parametric chirped pulse amplification in large-aperture KD₂PO₄, deuterated potassium dihydrogen phosphate crystals. The interaction of such laser radiation with matter represents a completely new fundamental physics. The direct study of the space–time structure of vacuums and other unknown phenomena at the frontier of high-energy physics and the physics of superstrong fields will be challenged. Expected applications will include the development of compact particle accelerators, the generation of ultrashort pulses of hard X-ray and gamma radiation for material science enabling one to probe material samples with unprecedented spatial and temporal resolution, the development of new radiation and particle sources, etc. The paper is translation from Russian [Kvantovaya Elektronika 53, 95 (2023)].

Ge-As-Se-Te（GAST）硫族化物玻璃拥有超过20 μm的超宽透射范围，是一种可应用于中红外（MIR）和远红外(FIR)波段的优良光学材料。通过熔融淬火法制备了Ge_xAs_40−xSe₄₀Te₂₀（x = 0、10、20、30、40 mol%）系列硫系玻璃，采用不同波长（800 nm，3 μm和4 μm）、功率和重复频率的飞秒激光辐照硫系玻璃，利用扫描电子显微镜（SEM）和拉曼光谱等手段研究了GAST的激光损伤特性。研究结果发现，Ge_xAs_40-xSe₄₀Te₂₀玻璃的激光诱导损伤阈值（LIDT）随着样品中Ge含量的增加而增加，在800 nm下Ge₃₀As₁₀Se₄₀Te₂₀玻璃的LIDT达到最高40.16 mJ/cm²。随着飞秒激光波长增加，系列玻璃的LIDT也逐步增加，Ge₃₀As₁₀Se₄₀Te₂₀在4 μm激光辐照下LIDT达到81.09 mJ/cm²。此外，研究结果表明样品LIDT随着激光的脉冲辐照数量和重复率的增加将逐渐减小。

GHz飞秒激光器相比于传统的百MHz飞秒激光器，其频域中相邻纵模的间隔更大、可分辨率更高，相同光谱范围内纵模密度更小，每个纵模分得的平均功率相对更高，在梳齿可分辨光谱学、直接频率梳光谱学、光学任意波形产生以及天文摄谱仪校准等诸多领域有着更重要的应用价值。文中从GHz飞秒脉冲的产生方案出发，着重对激光二极管泵浦的GHz重复频率全固态飞秒激光的产生方案以及相应的技术挑战进行了详细介绍，然后重点综述了国际上基于SESAM被动锁模以及克尔透镜锁模全固态GHz飞秒激光器的研究进展，并结合笔者所在课题组取得的初步研究结果对全固态GHz重复频率飞秒激光器的应用价值以及笔者所在课题组的研究目标进行了展望。