Ablation of aluminum thin films by ultrashort laser pulses

In this study, various results are presented for laser ablation experiments on aluminum and silicon, made in ambient air by means of subpicosecond las er pulses. These results include threshold fluences for plasma formation an d for the appearance of various spectral lines, and the single shot fluence required to remove aluminum layers of various specific thicknesses (rangin g from 10 to 500 nm) deposited on a silicon substrate. The threshold fluenc e for plasma formation is of the order of 0.1 J/cm(2). Threshold fluences f or the appearance of the spectral lines considered vary from 0.1 to about 5 J/cm(2). Finally, our results suggest that for high fluences, even for ult rashort laser pulses, the ablation depth is essentially determined by a lon g-range process, such as thermal conduction in the solid, rather than by th e short range optical depth. (C) 2001 American Institute of Physics.