Simulation of thermal transport and ablation of thin filmcopper by fs laser pulse

Author(s): F.M.Jasim, K.I.Mohammed, M.I.Azawe

The nonequilibrium thermal transport for electrons and lattice is described using two-temperature model simulation. The simulation was performed by finite difference time domain provided that dynamical optical and thermophysical properties had been taken into account. The effects of these properties on the electron and lattice temperatures were discussed. It was shown that the peak surface temperature is greater for long pulse duration and the film undergoes a superheated and experiencing a fast cooling compared to the other pulse durations. The ablation depth was found to increase as laser fluence increased. Results show diffusivity, as an electron temperature dependent, a more penetration was occurred resulting in a more ablation per pulse and lower ablation threshold. The dynamic changes of optical properties during laser irradiation, distributions of laser heat density, and electron and lattice temperature of a copper film irradiated by ultrashort-pulsed lasers were investigated, and was found that both the optical properties could drastically decrease during laser irradiation, leading to different laser energy deposition, both in magnitude and spatial distribution. The detailed features of the crater will be discussed.

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