三倍频熔石英激光损伤的吸收前驱体

 在三倍频熔石英激光损伤研究中，吸收前驱体的存在是造成熔石英材料表面损伤阈值远低于体损伤阈值的主要原因。以吸收作为主线，建立吸收前驱体引起的熔石英表面损伤模型，并讨论吸收前驱体与熔石英表面损伤的联系。针对金属元素微粒残留理论模拟了激光辐照过程中微粒周围温度场的变化，结果表明在脉冲时间内微粒周围温度很快到达损伤判据所给出的临界温度，通过激光损伤实验，证实吸收性微粒含量与损伤密度有密切联系。针对亚表面裂纹，建立一维模型计算受激后裂纹表面附近自由电子密度分布。计算结果和实验结果均表明：金属元素微粒和亚表面裂纹是熔石英激光损伤中重要的吸收前驱体，金属元素微粒对激光能量的吸收致使周围材料温度在脉冲时间内达到损伤判据温度2 000 K；受激后裂纹表面的自由电子密度达到1021 cm-3的水平，可导致对后续激光的强烈吸收；两种吸收前驱体极大降低了熔石英材料的表面抗损伤性能。

Surface damage precursors in triple-frequency fused silica

Damage precursors produced during grinding and polishing processes are the widely admitted damage initiators.Two models are built to examine the correlation between precursors and laser damage initiation.In the nano-absorber model,temperature field is simulated to describe the evolution of temperature at the hottest point within the pulse time.In the fracture model,electron density is calculated when the fracture surface is excited by laser shot.The results show that laser damage initiation and growth are s...