Photonic spin Hall effect by the spin-orbit interaction in a metasurface with elliptical nano-structures

The metasurface with elliptical nano-structures containing doubly degenerate geometrical charge is designed to investigate the enhanced spin-orbit optical interactions, numerically as well as experimentally. It is found that localized surface plasmon (LSP) resonance with orbital angular momentum (i.e., rotating SP vortex mode carrying extrinsic orbital angular momentum) can be induced under linearly polarized illumination. On the contrary, the LSP resonance without orbital angular momentum is formed under circularly polarized illumination. Moreover, based on the different LSP modes as results of spin-orbit interaction with alternative geometrical charge, directional propagations of surface plasmon polariton in two orthogonal trajectories depending on spin states of the incident light are presented with experimental demonstration, a phenomenon called photonic spin Hall effect.