Time-resolved studies of femtosecond-laser induced melt dynamics

This work presents time-resolved images of femtosecond-laser-induced melt dynamics in 60 nm gold films on glass substrates. Melt dynamics induced by laser radiation with focus diameters of 6 µm and 8 µm (FWHM) at constant laser fluence is investigated with a temporal resolution of 10 ns. In both cases, the formation of the microbumps and gold jets takes at least 250 ns. It is shown that the formation process can be compared to jetting behavior induced by cavitation bubbles near a free liquid surface. This is confirmed by SEM illustrating a re-entrant spike through a hole in the microbump.