Modelling the formation of nanostructures on metal surface induced by femtosecond laser ablation

We employ the particle-in-cell method to simulate the mechanisms of femtosecond (fs) laser interactions with a metallic target. The theoretical approach considers the solid as a gas of free electrons in a lattice of immobile ions and the laser fluences close to the ablation threshold. At first moments of the interaction, our simulations mapped out different nanostructures. We carefully characterized the rippling phase and found that its morphology is dependent on the distribution of the electron density and the period of the ripples depends on the laser intensity. The simulation method provides new insights into the mechanisms that are responsible for surface grating formation.

Simulation results obtained for circular polarization (after ∼10 fs, laser electrical field of 109 V/m, λD = 7 × 10−11 m): (a) electronic density profile and (b) surface electrical field profile.Highlights► We use the PIC method to simulate the interaction of femtosecond laser with a metallic target. ► We characterize the rippling phase. ► We provide new insights into the mechanisms responsible for surface grating formation.