Dynamics of spallation during femtosecond laser ablation studied by time-resolved reflectivity with double pump pulses

Takayuki Kumada, Tomohito Otobe, Masaharu Nishikino, Noboru Hasegawa, Terutake Hayashi

研究成果: Contribution to journalArticle査読

12 被引用数 (Scopus)

抄録

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 the bulk. The formation time of the spallation layer, as determined in this experiment, is attributed to the characteristic time of the mechanical equilibration corresponding to the thickness divided by the sound velocity of the photo-excited layer.

本文言語英語
論文番号011102
ジャーナルApplied Physics Letters
108
1
DOI
出版ステータス出版済み - 1 4 2016

All Science Journal Classification (ASJC) codes

  • 物理学および天文学(その他)

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