Experimental and theoretical investigation of the ablation mechanisms during femptosecond laser machining

In this work, a theoretical model based on molecular dynamics (MD) simulations and experimentation results of the femptosecond laser (FS) ablation, are applied for the description of ultrashort laser ablation of metals, with emphasis being given to the understanding of the material removal. The ablation of Fe with the use of 100 fs laser pulses, at a wavelength of 775 nm, is studied. Computational and experimental results have revealed that within the investigated laser fluences range (0.01 to 30 J/cm²), four different ablation areas accompanied by different ablation mechanisms, are distinguished. The threshold of the actual ablation has been determined to be at 0.1 J/cm². The ablation depth as a function of the laser fluence and the ablation threshold value have been evaluated and compared with the experimental data available.