Laser-induced electronic excitation, absorption and relaxation are the key issues in ultra-short laser interactions with dielectric materials. To numerically analyze these processes, a detailed non-equilibrium model is developed [1] based on the kinetic Boltzmann equations without any appeal to the classical Drude model. The calculations are performed including all possible collisional processes. As a result, electron energy distributions are obtained allowing a better analysis of ultra-short laser interactions. The results reveal a remarkable effect of the laser-field on collision frequencies resulting in smaller free-carriers absorption than the one predicted by commonly used rate-equation models. In addition, our calculations clearly demonstrates laser intensity limits for the applicability of Keldysh's equation for the photoionization process [2]. Both electron-electron and electron-phonon relaxation are then examined, and the mean energy density of the electron sub-system is investigated as a function of laser fluence and pulse duration. Because efficient bond breaking requires energy, these calculations provide the required thresholds. The dependency of the calculated fluence threshold on laser pulse duration is compared with the available experimental data. The obtained results also explain several recent pump-probe experiments. The developed model is useful for many laser applications including high precision in laser treatment, laser-assisted atomic probe tomography, and for the development of new powerful laser systems. [1] N. S. Shcheblanov and T. E. Itina, Appl. Phys. A DOI: 10.1007/s00339-012-7130-0 (2012) [2] N. S. Shcheblanov and T. E. Itina, submitted
