Analysis of Ultrashort Pulse Laser-Material Interaction Using the Two-Temperature Model

Ultrafast or ultrashort pulse lasers are increasingly being used for micro and nano-manufacturing. Because of the extremely short pulsewidth, there is usually not enough time for energy equilibrium to be established between the electrons and lattice in metals. Thus, instead of the conventional heat conduction model, the two-temperature model (TTM) is used to analyze laser-matter interactions for ultrashort pulse lasers. However, currently available non-linear two-temperature models generally require high computation capacity and long calculation time. In this study, a laser-matter interaction analysis strategy for a simplified dimensionless linear two-temperature model (SDLTTM) with proper heat source terms is developed to provide a quick and effective analytical method. SDLTTM is derived from a non-linear TTM with an assumption of constant material properties. The analytical solutions of the SDLTTM for lattice and electron temperatures for selected heat sources are obtained in the form of infinite series, and compared with other non-linear TTMs and experimental results for the electron temperature. Good correlation is obtained with the experimental results. Finally, the limitations of the SDLTTM, which result from the linearization assumption, are discussed.