Thermal analysis of thin multi-layer metal films during femtosecond laser heating

Abstract

Multi-layer metals films are widely used in modern engineering applications such as gold-coated metal mirrors used in high power laser systems. A transient heat flux model is derived to analyze multi-layer metal films under laser heating. The two separate system composed of electrons and the lattice is considered to take into account the electron–lattice interaction. The present model predicted the effects of underlying chromium’s thermal properties on temperature rise of the top gold layer. The effects of two adjacent and different metals with different electron–lattice coupling factors are analyzed for the heating mechanism of different lattices. The derived transient model combined with the two different conservation equations for the lattice and electrons are applied for the ultra short-pulse laser heating of a multi-layer film composed of gold and chromium.