Circular dichroism effects in nonlinear-optical response of planar chiral metamaterials

Circularly polarized optical second harmonic generation (SHG) is studied experimentally in regular arrays of planar G-shaped nanostructures. Circular dichroism in SHG is observed and the sign of the effect reverses with the handedness of the nanostructures, which is a signature of chirality in the nonlinear optical response.