Spin–orbit coupling in surface plasmon scattering by nanostructures

Abstract

The spin Hall effect leads to the separation of electrons with opposite spins in different directions perpendicular to the electric current flow because of interaction between spin and orbital angular momenta. Similarly, photons with opposite spins (different handedness of circular light polarization) may take different trajectories when interacting with metasurfaces that break spatial inversion symmetry or when the inversion symmetry is broken by the radiation of a dipole near an interface. Here we demonstrate a reciprocal effect of spin-orbit coupling when the direction of propagation of a surface plasmon wave, which intrinsically has unusual transverse spin, determines a scattering direction of spin-carrying photons. This spin-orbit coupling effect is an optical analogue of the spin injection in solid-state spintronic devices (inverse spin Hall effect) and may be important for optical information processing, quantum optical technology and topological surface metrology.

Enhanced Optical Chirality through Locally Excited Surface Plasmon Polaritons

“…Despite recent advances in the design and realization of near field sources capable of launching circular SPPs, such sources are not readily available in nature and their experimental realization remains challenging 33,35,41 . In this section we show that a chiral molecule can mimic the chiral behavior of a circularly polarized near field source.…”

Spin-dependent optics with metasurfaces

“…Spin-splitting can also be directly observed using circularly polarized light as incidence as an asymmetric excitation of surface plasmon propagating towards the left-and right-hand sides of the slit. When an appropriate angle of incidence is chosen, the asymmetry is optimal and is revealed as a spin-dependent unidirectional excitation of the surface plasmon (see Figure 8B and C) [97][98][99]. Moreover, such asymmetric effects can be demonstrated for even a single particle placed on the surface of metal surface [98][99][100].…”

“…When an appropriate angle of incidence is chosen, the asymmetry is optimal and is revealed as a spin-dependent unidirectional excitation of the surface plasmon (see Figure 8B and C) [97][98][99]. Moreover, such asymmetric effects can be demonstrated for even a single particle placed on the surface of metal surface [98][99][100]. As a direct implication, the particle is optically pushed in opposite directions for the incidence of different circular polarizations as demonstrated as the mechanical effects from spin-orbit coupling [101,102].…”

Plasmonic polarization generator in well-routed beaming

“…Compared with conventional optical elements, plasmonic devices provide a more compact and efficient means to manipulate the polarization of light (e.g., plasmonic polarizers 1-5 , polarization rotators and converters [6][7][8][9][10][11] , polarization detectors 12 , etc.). Recently, plasmoninduced spin-orbital coupling has generated strong interest in the field of photonics [13][14][15][16][17] , primarily due to the possibility of polarization and phase modulation. In fact, the vectorial structure of the surface plasmon field gives rise to unique properties in the conversion of optical fields between propagating light and bounded surface plasmon polaritons (SPPs), where the polarization information of light can be reloaded by special SPPs in a controllable way [18][19][20][21][22] .…”