Understanding deformation behavior of gold film induced by ultrafast laser with different fluences

The deformation behavior of the metal film with ultrafast laser irradiation is complicated for the multiple physical processes. In this study, experimental research of the gold film with the thickness of 40 nm irradiated by the single ultrafast laser pulse with different fluences is carried out. The deformation evolutions, including bump deformation, bump rupture, and flowering structure at ablation edge, are analyzed by scanning electron microscope and atomic force microscope. Molecular dynamic method coupled with two temperature model is also used to quantitatively analyze the temperature and stress, in order to demonstrate the material responses with different laser fluences. The mechanism of the bump deformation with low fluence and the flowering structure at ablation edge with relatively high fluence are also illustrated.