Propagation Dynamics of Photonic Toroidal Vortices Mediated by Orbital Angular Momenta

Abstract

The dynamics of vortex rings in fluids have long captivated researchers due to the intriguing complexity of their behavior, despite the apparent simplicity of their structure. In optics, photonic toroidal vortices constitute a novel class of three-dimensional, space-time nonseparable structured light fields that carry transverse orbital angular momentum. However, as solutions to the dispersive form of Maxwell's equations, these wavepackets do not survive upon nondispersive propagation, and their dynamics remain elusive. In this article, the dynamics of photonic toroidal vortices under various dispersion regimes, mediated by both transverse and longitudinal orbital angular momentum, are investigated through simulations and experiments. The results reveal that the motion of a toroidal vortex is strongly affected by the presence of longitudinal orbital angular momentum. The swirling flow destabilizes the toroidal structure under dispersion conditions and induces topological transformations in the vortex line characterized by its annihilation and subsequent reformation in vacuum. Remarkably, the renascent toroidal vortex exhibits robust propagation in vacuum while maintaining its toroidal structure. These findings are supported by experimental validation and highlight the potential of photonic toroidal vortices as controllable channels for directional energy and information transfer.

6 figures in the main text

References in corpus (11)

• Photonic Cyclone: spatiotemporal optical vortex with controllable transverse orbital angular momentum
• Optical skyrmions and other topological quasiparticles of light
• Free-space propagation of spatio-temporal optical vortices (STOVs)
• Photonic toroidal vortex
• Supertoroidal light pulses: Propagating electromagnetic skyrmions in free space
• Observation of Toroidal Pulses of Light
• Second-harmonic generation and the conservation of spatiotemporal orbital angular momentum of light
• Generation of robust spatiotemporal optical vortices with transverse orbital angular momentum beyond $10^2$
• Nondiffracting Supertoroidal Pulses: Optical "Kármán vortex streets"
• Free-Space Propagation and Skyrmion Topology of Toroidal Electromagnetic Pulses
• Formation and Controlling of Optical Hopfions in High Harmonic Generation