Polarization Effects in Optical Second Harmonic Generation from Chiral Nanostructures

Abstract

The main experimental results that have been recently obtained for the linear and nonlinear optical responses of ordered two-dimensional arrays of planar chiral metallic nanostructures are considered. These experimental results demonstrate that the polarization state of the linear and nonlinear optical responses of metasurfaces are substantially determined by the chirality of a single nanoelement and the related spatial distribution of the optical second harmonic generation intensity. As a result, circular dichroism effects appear in the linear and nonlinear optical responses of a chiral metasurface. The anisotropy of the second harmonic is experimentally shown to play a substantial role in the effects of extrinsic chirality, which is determined by the spatial symmetry of an array of nanoelements. The main properties of circular dichroism in the quadratic optical response are supported by numerical calculations and symmetry analysis of structures.