Laser-ablated volume and depth as a function of pulse duration in aluminum targets

The ablated depth and volume per laser pulse from an aluminum target were measured for pulse durations that ranged from 80 fs to 270 ps at an average fluence of similar to100 J/cm(2) and a wavelength of 0.8 mum. The ablated volume showed a flat maximum for subpicosecond pulses and a minimum for similar to6 ps. The crater diameters were rather constant up to pulse durations of similar to6 ps and increased for larger pulse durations. As a result, the ablated depth also showed a plateau for subpicosecond pulses but decreased monotonically with pulse duration. A physical interpretation of these results and their consequences for laser applications are discussed. (C) 2005 Optical Society of America.