Anomalous Zeeman splitting of plasmonic resonances in a magnetoplasmonic particle under vortex beams

Abstract

The orbital angular momentum (OAM) of light opens up a new physical dimension for studying light–matter interactions. In this paper, we revealed that the Zeeman splitting of plasmonic resonances in a magnetoplasmonic particle under OAM beams is induced by only a transverse magnetic field, breaking the preconception that Zeeman splitting of plasmonic resonances under non-OAM sources is induced by a longitudinal magnetic field. Zeeman splitting of plasmonic scattering resonances occurs under circularly polarized light carrying OAM, while no Zeeman splitting is observed in magnetoplasmonic particles under circularly polarized light carrying no OAM. These anomalous phenomena are the result of the longitudinal dipole excited by OAM. We also demonstrate tunable rotation of longitudinal dipolar radiation patterns by an external magnetic field. The reported research on magnetoplasmon behavior with OAM would provide great potential to control electromagnetic waves and add additional degrees of freedom to the spectroscopies.