Phys. Rev. X 3, 041031 (2013)

Credit: © 2013 APS

Vortex solitons are of interest because they possess orbital angular momentum fields that are capable of carrying data and energy and, being solitary waves, are robust against diffraction and crosstalk. Now, Falk Eilenberger and co-workers from Friedrich-Schiller-Universität Jena and the Institute of Photonic Technology in Germany report what they claim is the first observation of vortex light bullets — discrete, spatiotemporal, solitary waves with orbital angular momentum. The vortex light bullets are excited in photonic-crystal fibre arrays (with a solid core of increased refractive index instead of air holes, a core radius of 10.3 μm and a centre-to-centre distance of 34.7 μm) by femtosecond pulses, and analysed with a spatiotemporal cross correlator. By performing experiments and rigorous simulations, the team found that, unlike ordinary light bullets, vortex light bullets decay into a set of desynchronized light bullets after a considerable propagation length. Furthermore, they are robust against higher-order effects and asymmetric excitation, occur in a limited energy window, and are characterized by temporal and energetic synchronization up to a certain sample length. These findings provide valuable insights into the complex behaviour and internal dynamics of vortex light bullets.