Nonlocal effects on second harmonic generation in nanofilm plasmonic structure

We numerically studied nonlocal effects that affect enhancement of second harmonic generation (SHG) in a metal nanofilm plasmonic structure. The hydrodynamical Drude model was implemented for metal film in time-domain simulations that combine nonlocal effects and nonlinear effects. It is found that the nonlocal effect on the second harmonic wave is more severe than that on the fundamental wave. The SHG enhancement is thus weakened in the nonlocal response compared with the usual local response described by the Drude model, and the reduction becomes appreciable for the metal film thickness down to nanomenter scale.