Observation of the orbit-orbit interaction of light in plasmonics

The orbit–orbit interaction of light is the interaction between the intrinsic and extrinsic orbital angular momenta associated with optical vortex beams and varying beam trajectories, respectively. We report the orbit–orbit interaction of light in a plasmonic ellipse cavity, whose unique geometry facilitates vortex–trajectory interplay when a vortex is considered in one of the foci of the ellipse. This interaction, manifested by vortex-dependent shifts, opens a new paradigm for light manipulation by leveraging the manifold vortex states.