We predict that vortex dipoles nested in light beams trapped in graded-index media can undergo closed Berry trajectories, yielding periodic vortex annihilations and revivals along the light-propagation direction. The vortex revivals from vortex-free wave fronts are mediated by Freund stationary point bundles that carry the necessary Poincaré–Hopf indices. Vortex spiraling and spontaneous generation of circular-edge dislocations are also found to occur.
Molina, G., Torner, L., Wright, E., Garcia-Ripoll, J., Perez-Garcia, V. Vortex revivals with trapped light. "Optics letters", Octubre 2001, vol. 26, núm. 20, p. 1601-1603.