<title>Ablation thresholds of metals with femtosecond laser pulses</title>

Abstract

The laser ablation threshold experiments were performed on pure metals with the fs Gaussian laser beam focused to 41.5 mm spot diameter onto metal surfaces. Three different ablation thresholds were distinguished. The multi-shot ablation threshold for Cu with 70 fs pulse was found to be 0.018 J/cm² and of one order to magnitude lower than that one observed previously. In the fluence range of 0.018- 0.2 J/cm² the ablation rate was approximately equal to 0.01 nm/pulse. The threshold dependence on the pulse duration was demonstrated in the range of 70 fs-5 ps for Cu. As the laser pulse width increased, the ablation threshold had the tendency to be higher. The ablation rate dependence on laser fluence for the other metals under study in our experiments with 70 fs was similar to that of CU.