Generation and Control of Ultrafast Directional Photocurrents at Nanoscale Using Symmetry-Broken Hybrid Graphene Nanoplasmonic Metasurfaces

The generation of directional photocurrents via a variety of mechanisms is essentially linked to the breaking of spatial inverse and/or time-reversal symmetries. Here we introduce a class of optoelectronic metasurfaces, more specifically hybrid graphene nanoplasmonic metasurfaces with broken inversion symmetry, for the generation of arbitrarily and spatially varying ultrafast directional photocurrents at nanoscales. We further apply this concept for efficient emission of pulsed THz radiation and direct generation of THz vector beams.