Spin-orbit coupling and conservation of angular momentum flux in non-paraxial imaging of forbidden radiation

Abstract

Rigorous, closed form expressions are derived for non-paraxial imaging of sources of multipole radiation from which conservation of angular momentum (AM) flux is established. Coupling of spin and orbital optical AM flux is also quantitatively investigated, highlighting the importance of spin-orbit interactions in high numerical aperture imaging. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.