Plasmonic Toroidal Vortices

Toroidal vortices, or vortex rings, are torus-shaped vortices observed in various fluid systems. Recently, optical toroidal vortices, novel solutions to Maxwell's equations, have been experimentally observed (Nat. Photonics, 2022, 16, 519). Thus, their nanoplasmonic counterparts, namely plasmonic toroidal vortices, are highly anticipated. This study aims to elucidate the generation and manifestation of plasmonic toroidal vortices. To achieve this, a technique involving the illumination of a gold nanotorus with a radially-polarized beam is employed. Notably, the plasmonic toroidal vortices exhibit a distinct photon flow trajectory along the minor radius of a nanotorus. This work presents an advancement in toroidal vortices within the plasmonic regime. The study reports the manifestation and formation of plasmonic toroidal vortices, a counterpart to toroidal vortices observed in fluid systems and recently in optics. Through illuminating a plasmonic nanotorus with a radially-polarized beam, a novel photon flow along the nanotorus's minor radius, identified as plasmonic toroidal vortex is observed. This finding contributes to the understanding of toroidal vortices within the plasmonic realm. image