Molecular dynamics study of the potential formation thickness of ultrafast laser induced sapphire crystal surface recast layer

Currently, laser-induced damage is a prominent focus in the field of ultrafast laser micro/nano processing. This article focused on the potential formation thickness of the ultrafast laser-induced sapphire crystal surface recast layer. To investigate the influence of laser parameters and crystal orientation on the recast layer potential formation thickness at the atomic scale, a molecular dynamics model of laser irradiation sapphire crystal was constructed. Experiments of laser-induced recast layer formation were carried out, and the effects of laser fluence, pulse width, and wavelength on the surface recast layer were analyzed. The results show that the ejected atom start formation time is significantly influenced by pulse width, while the potential formation thickness of the recast layer is mainly influenced by the deposited laser energy. Moreover, under the same laser energy, the damage extent in sapphire crystal caused by laser irradiation along the (0001) orientation is significantly weaker compared to irradiation along the (1–100) and (11–20) orientations. This article could provide theoretical and process references for suppressing the ultrafast laser-induced sapphire crystal surface recast layer formation.