Fig. 1. (a) Schematic of the Au-Ti double-layered film. The thickness of the Au layer is x. The thickness of the Ti layer is l=500  nm. (b) The phonon temperature field on an Au film surface irradiated by a femtosecond laser pulse at 15 ps with a gold thickness of 500 nm. The laser fluence F=0.2  J/cm2, pulse duration tp=100  fs, and the laser wavelength λ=800  nm.

Fig. 2. Electron and phonon temperature field distributions at 15 ps along the depth of Au-Ti double-layered film; the gold thickness x=500  nm. The laser fluence F=0.2  J/cm2, pulse duration tp=100  fs, and the laser wavelength λ=800  nm.

Fig. 3. Dependence of phonon temperature and temperature difference across the gold layer of Au-Ti double-layered film on the Au layer thickness. The laser fluence F=0.2  J/cm2, pulse duration tp=100  fs, and the laser wavelength λ=800  nm.

Fig. 4. Maximum phonon temperature change at the surface of the Au layer as function of the laser fluence with three different Au layer thicknesses. The laser pulse duration tp=100  fs and the laser wavelength λ=800  nm.