Enhanced second harmonic generation from a quasi-periodic silver dendritic metasurface.

The preparation of the vast majority of nonlinear optical metal metasurfaces currently relies on complex top-down methods such as electron beam or ion beam etching, which are expensive and difficult to meet the requirement of large area preparation. In this paper, an easily prepared quasi-periodic silver dendritic metasurface model with high Q factor is established in the near-infrared band based on a simple and easy-to-operate electrochemical deposition method. The simulations prove that the silver dendritic metasurface has a high Q factor (exceeds 10 4 ) because of its strong electric field localization ability, which is analogous to the superposition of multiple split-ring resonators. It is demonstrated that the second harmonic generation (SHG) intensity of the dendritic metasurface at a large incident angle (such as 85°) is about 30 times that of the metasurface at a small incident angle when the x-polarized pump light is incident obliquely to break the centrosymmetry of the metasurface. The influences of the incident angle or dendritic structure's dimensions on the Q factor and SHG efficiency have also been researched through a lot of simulation. This easily prepared quasi-periodic silver dendritic metasurface SHG device may provide a new avenue for the development and application of miniature, integratable nonlinear optical devices.