AXISYMMETRIC MODELING OF FEMTOSECOND-PULSE LASER HEATING ON METAL FILMS

An axisymmetric, dual-hyperbolic, two-temperature model is developed to investigate the thermal response of ultrashort laser pulse interaction with a metal film. The absorbed laser energy is treated as a volumetric heat source, which includes the effect of the ballistic motion of the excited electrons into deeper parts of the material. The temperature-dependent thermophysical properties are incorporated to fully describe the thermal transport in electrons and the lattice. A fourth-order finite-difference algorithm is employed to solve the coupled nonlinear heat conduction equations. Both the electron and lattice temperatures in a gold film irradiated by Gaussian laser beams are computed and presented along the r and z axes, respectively. In addition, the suitability of using a one-dimensional, two-temperature model for predicting the damage threshold fluence is examined.