Ultrafast heat transfer dynamics induced by femtosecond laser pulse in fused silica

Femtosecond laser interacts with material shows nonlinear absorption and low thermal diffusion due to the ultrashort pulse width and ultrahigh peak power, which makes it important in the manufacturing of high-precision micro-nano devices. An ultrafast dynamic model for transient photoionization and non-equilibrium heat transfer of femtosecond laser pulses interacting with fused silica was established. By numerical solution, the spatio-temporal evolution of carrier density and non-equilibrium electron and phonon temperature of fused silica excited under femtosecond laser single pulse was obtained, and the nearly linear regulation law of electron-phonon coupling time with laser energy density and pulse width under non-equilibrium conditions was obtained. The variation laws of transient electron thermal conductivity, thermal capacity and electron-phonon coupling coefficient were further investigated in details. And the above simulation results were analyzed and discussed.