Ultrashort laser-solid interaction: ionisation, absorption, and ablation

Summary form only given. We developed an analytical model for ultrashort-pulse laser-ablation of solids. In comparison with long-pulse interaction, the distinctive feature of femtosecond pulse interaction is that hydrodynamic motion is suppressed. The exchange of energy between electrons and ions is negligible during the interaction time. In order to achieve ablation, laser intensity has to be increased in inverse proportion to pulse duration. For intensities /spl sim/10/sup 13/-10/sup 14/ W/cm/sup 2/ ionisation takes place at the beginning of the laser pulse for practically any target material. Laser energy is absorbed only by free electrons in metals or by stripped electrons in dielectrics. We used a normal skin-effect approach in the analysis of immobile solid-density plasma.