Proceedings PaperMicroscopic mechanisms of initiating of nonthermal femtosecond laser-induced ablation of transparent solid dielectrics
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These are discussed microscopic physical processes underlying early phases of femtosecond laser-induced damage and ablation of wide band-gap solid dielectrics. They can result in 1) variations of energy-level structure of electron subsystem (in particular band-gap), and 2) instability of crystal structure. Those two microscopic processes are local and can be detected through different effects (variations of linear and nonlinear optical response and x-ray diffraction) each having its own characteristic time. There is analysed and estimated possibility of developing of instability of crystal structure and structure of electron energy levels of the solids under action of positive feedbacks. The feedbacks results from laser-induced ionization, straight action of electric field of laser radiation on ions, both resulting in increasing of density of laser-induced point defects. Estimations are obtained on the basis of the simplest relations describing laser-induced microscopic processes. Obtained results are compared with experimental data and shown to be capable of explaining some features of femtosecond laser interaction with transparent media.