Spatiotemporal Helicon Wavepackets

Propagation-invariant or nondiffracting optical beams have received considerable attention during the last two decades. However, pulsed nature of light waves and structured property media like waveguides are often overlooked. We here present a four-dimensional spatiotemporal approach that extends unifies both concepts conical helicon beams, mainly studied in bulk media. By taking advantage tight correlations between spatial modes, topological charges, frequencies embedded an field, we reveal propagation-invariant (dispersion- diffraction-free) space-time wavepackets carrying orbital angular momentum (OAM) evolve on spiraling trajectories time space multimode fibers. Besides their intrinsic linear nature, show such wave structures can spontaneously emerge when rather intense ultrashort pulse propagates nonlinearly OAM modes. With emerging technologies pulse/beam shaping, fibers, modal multiplexing, our proposed scheme to create OAM-carrying could find plethora applications. Finally, work provides general explore dynamics three-dimensional with properties, outlook this topic goes well beyond optics, since being nowadays various branches physics as acoustic spanners, polaritonics, plasma waves, particle beams.