Dynamics of spallation during femtosecond laser ablation studied by time-resolved reflectivity with double pump pulses
Dynamics of spallation during femtosecond laser ablation studied by time-resolved reflectivity with double pump pulses
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DOI：
10.1063/1.4939231
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发表时间：
2016-01
影响因子：
4
通讯作者：
T. Kumada;T. Otobe;M. Nishikino;N. Hasegawa;T. Hayashi
中科院分区：
文献类型：
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作者：
T. Kumada;T. Otobe;M. Nishikino;N. Hasegawa;T. Hayashi
采用时间分辨反射率法研究了飞秒激光烧蚀熔融石英过程中光机械散射的动力学过程。反射率的振荡是由在样品表面反射的探测脉冲与spp层之间的干涉引起的，并且当在第一泵浦脉冲之后的几皮秒的时间间隔Δτ内用第二泵浦脉冲照射样品表面时，反射率的振荡被增强。然而，随着Δτ的增加，振荡幅度以10 ps的指数衰减时间减小。当Δτ超过20 ps时，振荡消失。该结果表明，spectrum层的形成时间约为10 ps。Δτ短于10 ps的第二泵浦脉冲激发体样品。之后分离由第一和第二泵浦脉冲光激发的溅射层。与此相反，Δτ大于形成时间的脉冲激发并破碎已经与形成时间分离的溅射层。
The dynamics of photomechanical spallation during femtosecond laser ablation of fused silica was studied by time-resolved reflectivity with double pump pulses. Oscillation of reflectivity was caused by interference between the probe pulses reflected at the sample surface and the spallation layer, and was enhanced when the surface was irradiated with the second pump pulse within a time interval, Δτ, of several picoseconds after the first pump pulse. However, as Δτ was increased, the oscillation amplitude decreased with an exponential decay time of 10 ps. The oscillation disappeared when Δτ exceeded 20 ps. This result suggests that the formation time of the spallation layer is approximately 10 ps. A second pump pulse with Δτ shorter than 10 ps excites the bulk sample. The spallation layer that is photo-excited by the first and second pump pulses is separated afterward. In contrast, a pulse with Δτ longer than the formation time excites and breaks up the spallation layer that has already been separated from ...