Optical rectification and spin-momentum locking in symmetry-breaking plasmonic metasurfaces (Conference Presentation)

New nano- or micro-patterned metal nonlinear metasurfaces, robust against temperature and more sustainable than current IR materials, could respond across the LWIR-to-SWIR spectrum (no band gap) for long-distance data/power transfer, thermal management, sensing, navigation, and detection. In this presentation, we discuss our recent discovery of longitudinal and transverse optical rectification (OR) in an asymmetric plasmonic grating that is inherently linear. A periodic Au stripe array breaks inversion symmetry perpendicular to the stripes, so that direct (zero frequency) electronic, rectified current, due to selective excitation of only one SPP mode, flows with incident photons polarized perpendicular to the stripes. We also measured the influence of the photon helicity on the OR current, from coupling of the spin of propagating surface plasmon-polaritons (SPPs) to their linear momentum and to the angular momentum of incident photons. It is interesting that bosonic SPPs generate this electrical current. Simple ‘photon drag’ and other models of electronic current do not completely explain the experiment. We discuss scientific advances to better understand these phenomena.