Numerical study of ultrashort laser pulse interactions with metal films

A dual-hyperbolic two-step radiation heating model is presented to investig ate ultrashort laser pulse interactions with metal films, This model extend s Qiu and Tien's theory by including the effect of heat conduction in the l attice, In addition, the depth distribution of laser intensity is modified by adding the ballistic range to the optical penetration depth. The effects of temperature dependence of the thermophysical properties also are examin ed For comparison, the proposed model and the existing theories, the parabo lic two-temperature model, Qiu and Tien's theory, and Fourier's law, are so lved using a mesh-free particle method. Numerical analysis is performed wit h gold films; the results ave compared with experimental data of Qiu, Jubha sz, Suarez, Bron, and Tien, and Wellershoff; Hohlfeld, Gudde, and Matthais. It is shown that this current model predicts more accurate thermal respons e than the existing theories considered in this study. it is also found tha t the inclusion of the ballistic effect to the depth distribution of laser intensity significantly improves the melting threshold fluence prediction.