Ultrafast Deformation in Femtosecond Laser Heating

Abstract

The hot-electron blasting model is extended in this work to describe the ultrafast deformation in thin metal films during the sub-picosecond to picosecond domain. The driving force exerting on the cold metal lattices is induced by the highly heated electrons, dictated by both the temperature and temperature gradient established in the hot electron during the picosecond transient. Since the metal lattices remain almost thermally undisturbed in this highly non-equilibrium regime, the resulting ultrafast deformation patterns cannot be described by the classical dynamical theory of thermoelasticity. The phonon-electron interaction model is used to describe the electron temperature and hence the driving force. The dominating parameters characterizing the nonlinearly coupled ultrafast heating and deformation are identified. Method of lines is used to solve the coupled field equations describing ultrafast deformation in the picosecond domain.