Ultrafast laser-induced thermoelastic behavior in metal films

When a thin metal film is irradiated by an ultrafast laser, the energy of the laser is first absorbed by electrons and then transferred to the lattice. In addition, a thermoelastic wave is generated due to the thermoelastic coupling effect. An ultrafast thermoelasticity model utilizing the parabolic two-step heat conduction model and the generalized thermoelastic theory was formulated to describe the thermoelastic behavior of a thin metal film irradiated by a femtosecond laser pulse. The temporal profile of the ultrafast laser was regarded as being non-Gaussian. An analytical–numerical technique based on the Laplace transform was used to solve the governing equations and the time histories of the electron temperature, lattice temperature, displacement and stress in a gold film were analyzed. The influence of the thickness of the film was also analyzed. In addition, the propagation of the stress wave through the film was analyzed.