Formation and modulation of multi-pulse femtosecond laser-induced periodic surface structures by electromagnetic and partial differential equation simulations.

In order to demonstrate the formation of laser-induced periodic surface structures (LIPSS), simulations were performed to investigate the effect of multiple femtosecond laser pulses with different laser energy densities on a Ti6Al4V surface. In this work, a set of partial differential equations calculating the electron and lattice temperature variations, followed by coupling with an electric field, is used to analyze the evolution of the periodic surface structure induced by the interaction of the femtosecond laser with the material. As the number of pulses increases, the surface structure of the material changes from none to produce LIPSS structure and from low spatial frequency LIPSS (LSFL) structure to high spatial frequency LIPSS (HSFL) structure. In order to compare the results, single-point laser scanning ablation experiments were carried out at femtosecond laser energy. The experimental results are consistent with the simulation results.