Energy band structure perturbation induced deviation on precise ultrafast laser nano-structuring

The effect of the material lattice structure during the laser nano-structuring is generally overlooked. Here, we reveal the energy band structure perturbation at different polarizations, and its underlying mechanism functioning on the ultrafast laser nano-structuring. This phenomenon is confirmed by the variation in deviation of femtosecond laser-induced periodic surface structures (LIPSS) orientation on thin-film lithium niobate (LiNbO₃). An increase in the laser fluence leads to a notable enlarging in the effective bandgap of LiNbO₃ from 3.78 to 5.70 eV, weakening the impact of polarization-dependent intrinsic perturbations within LiNbO₃ that contribute to the deviation of LIPSS orientation. Precise writing of polarization dependent structures and selective reading of corresponding information are realized via directional modulation of LIPSS. The study of energy band structure perturbation effect develops a novel mechanism for the deviation angle modulation of nano-structuring at the accuracy compensation within 1°, thus promising enhanced precision for future laser nano-structuring applied in advanced nano-optics devices.