Ablation threshold dependence on pulse duration for copper

Laser ablation of Cu by short pulse laser (800 nm wavelength, 70 fs pulse duration, 0.01-28 J/cm2 fluence range) in air was studied. Three different ablation thresholds were distinguished in all metals. The ablation thresholds for Cu were found to be 0.018, 0.18, and 0.25 J/cm2. The lowest ablation threshold was of one order of magnitude lower than the one observed previously. In the fluence range of 0.018-0.18 J/cm2 the ablation rate was ∼0.01 nm per pulse. A dependence of the threshold on the pulse duration was demonstrated in the range of 70 fs-5 ps. As the laser pulse duration increased, the ablation threshold had the tendency to be higher