A finite difference method for studying thermal deformation in a double-layered thin film exposed to ultrashort pulsed lasers

Ultrashort pulsed lasers have been attracting worldwide interest in science and engineering because the lasers with pulse durations of order of sub-picoseconds to femtoseconds possess exclusive capabilities in limiting the undesirable spread of the thermal process zone in the heated sample. It is important to study the thermal deformation induced by ultrashort pulsed lasers to prevent thermal damage. In this article, we apply a staggered finite difference method to study thermal deformation in a two-dimensional double-layered metal film exposed to ultrashort pulsed lasers. The method is obtained based on the parabolic two-step heat transport equations. It accounts for the coupling effect between lattice temperature and strain rate, as well as for the hot-electron blast effect in momentum transfer. The developed methodology allows us to avoid non-physical oscillations in the solution as demonstrated by a series of numerical experiments.