Numerical simulation of heat transfer mechanisms during femtosecond laser heating of nano-films using 3-D dual phase lag model

In the present work we investigate femtosecond laser heating of nanoscale metal films irradiated by a pulsating laser in three dimensions using the Dual Phase Lag (DPL) model and consider laser heating at different locations on the metal film. A numerical solution based on an explicit finite-difference method has been employed to solve the DPL heat conduction equation. The stability criterion for selecting a time step size is obtained using von Neumann eigenmode analysis, and grid function convergence tests have been performed. The energy absorption rate, which is used to model femtosecond laser heating, has been modified to accommodate for the three-dimensional laser heating. We compare our results with classical diffusion and hyperbolic heat conduction models and demonstrate significant differences among these three approaches. The present research enables us to study ultrafast laser heating mechanisms of nano-films in 3D.