Photonic Hall Effect via Optically-Induced Near-Field Asymmetry in Arrays of Au Cross-Shaped Nanoantennas

Many unique applications of plasmonic metasurfaces, such as the photonic spin Hall effect and planar chirality, are based on unique arrangements of shapes and positions of nanoantennas to generate specific phase changes and structural asymmetry. In this article, we demonstrate the unique ability of in-plane scattering of plasmonic metasurfaces to translate polarization-induced asymmetric near fields and photonic lattice modes into highly measurable far field scattering features. This allows one to spatially (directionally) sort out scattered photons when the incident light is circularly polarized and the metasurfaces consist of symmetric nanoantennas without any shape or position dispersion. Therefore, depending on their energies, photons with such polarization states can be spatially scattered along specific directions due to their self-imposed asymmetric plasmonic–photonic features. The plasmonic metasurface studied in this work includes an array of structurally symmetric gold cross-shaped nanoantennas, supporting hybridized multipolar plasmonic resonances with strong degrees of spatial near field asymmetries when interacting with circularly polarized light. Such resonances are coherent with each other via the lattice modes, promoting photon-spin-dependent in-plane scattering. Our results show that the case of L ± 45 will also show similar features.