Simulation of ultrashort double pulse laser ablation of metals

Abstract : We perform a hydrodynamic simulation of laser ablation of metals to explain the results of recent experiments with subpicosecond double pulses (2  2 J/cm2). In the experiments, the time delay del between the pulses varies from 0.1 ps to 200 ps. When the delay is much shorter than the electron-ion relaxation time ei (delay << ei) the crater depth is the same as for a single pulse of energy 4 J/cm2. For the intermediate delays (delay ~ ei) the crater depth monotonically drops. For the long delay delay >> ei the crater depth corresponds to that obtained with a single pulse. The results of the hydrodynamic two-temperature simulations performed with realistic absorption and multiphase equation of state explain the observed behavior.