Optical Spin-Hall Effects in Nanophotonic Technologies

Spin-orbit coupling of light describes how spin angular momentum of light (associated with circular polarisation of an electromagnetic wave) is coupled to orbital angular momentum of light (associated with the energy flow and propagation direction). This effect provides interesting applications in polarisation-enabled control of optical signals, or in reverse, controlling light polarisation, sensing applications and quantum optical processes. Near nanostructures capable of supporting waveguided modes, the spin-orbit coupling is mediated by the transverse spin carried by guided modes: electric field spins around an axis perpendicular to the wavevector, with the spinning sense determined solely by the propagation direction. The spin-orbit coupling in such type of modes, results in the so-called photonic spin-Hall effect, in analogy to spin-Hall effect for electrons. In this talk we will overview the effects associated with the photon spin when circularly polarised light interacts with plasmonic nanostructures and metamaterials. Spin-dependent directional excitation of guided modes, spin-orbit coupling in surface plasmon scattering associated with the unusual, transverse spin of surface polaritons, and spin-dependent optical forces will be discussed. Photonic spin-orbit interactions provide an important tool for harvesting functionalities and applications of circularly polarised light in numerous photonic and quantum technologies, and metrology.