Ultrafast dynamics of high-contrast nano-grating formation on gold film induced by temporally shaped femtosecond laser

We theoretically investigated the ultrafast dynamics of high-contrast nano-grating formation on gold film surface with respect to non-equilibrium thermal excitation processes. It is proposed that the high-contrast nano-grating can be desirably achieved by optimizing the non-equilibrium thermal dynamics processes. The grating contrast can be largely promoted by 64% with adjusting thermal dynamics via tailoring temporally shaped femtosecond laser. The results are attributed to the competitive energy transfer routes between electrons thermal diffusion and electron–phonon relaxation processes during grating formation, which can be well manipulated by temporally shaped femtosecond laser. The study provides for strategy for production of high-quality periodic surface structures with sharp grating profiles.