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. (C) 2010 Elsevier Ltd. All rights reserved.