Modeling of femtosecond laser damage threshold on the two-layer metal films

The heating processes of the single-layer gold thin film and the two-layer film assembly of gold padded with other metal (silver, copper and nickel) irradiated by femtosecond laser pulse are studied by the two-temperature model. It is found that the substrate metal can change energy transport, which is corresponding to the temperature changing process, and the thermal equilibrium time. Compared with the single-layer gold film at the same laser fluence, the two-layer film structure can change the damage threshold of the gold surface. Our results indicate that we can maximize the damage threshold of the gold film surface by altering the thickness ratio of the gold layer and the substrate layer in the two-layer film assembly.