Measuring the deterministic character of laser damage of dielectrics in ultrashort pulsed regime

The use of ultrashort pulsed lasers in the field of material processing has been widely studied and its ability of micro-machining any kind of material by direct processing with a high degree of accuracy has been demonstrated. Femtosecond laser processing is especially relevant since its spatial accuracy is closely related to its “deterministic” character, meaning that damage/ablation will occur systematically on regions where the local fluence on the material (depending on the intensity distribution of the laser beam) exceeds a very precise threshold fluence. This characteristic must be seen in opposition to the stochastic character of damage threshold observed for “long” pulses (typically ≫ 10 ps), for which damage appearance is known to be probabilistic. This property, combined with the reduced thermal diffusion, makes possible the ablation of materials with submicrometer precision, opening the way towards nano-machining applications.