Generation and spatiotemporal dynamics of a propagation-invariant weak chirp dual Airy Bessel vortex wave packet

Abstract

It is an interesting and meaningful exploration to produce a new type of multi-dimensional spatiotemporal light field with non-diffraction and self-focusing properties. In this paper, a novel scheme is proposed to construct a tunable weak chirp dual Airy Bessel vortex (CdAiBV) spatiotemporal wave packet (WP), and the generation experimental setup is also demonstrated. Significantly, the generated higher-order wave packet carries optical vortices with a complex structure and presents propagation-invariant property within a fairly long distance. Dependence of the targeted wave packet’s non-diffraction properties and self-focusing effects on the topological charge n and phase mask’s control parameter β, and influence of the initial frequency chirp coefficients C1 and C2 on the acceleration and deceleration characteristics of the temporal Airy pulse and the spatiotemporal structure of the CdAiBV wave packet are investigated. Furthermore, evolution of the topological phase, energy flow, and orbital angular momentum (OAM) density of higher-order wave packets propagating in the time-space domain are considered. Results demonstrate that the generated spatiotemporal CdAiBV wave packet would undergo a process of spatial “autofocus to defocus” and temporal “deceleration and collapse” during propagation, and only a fairly weak chirp is needed in such a process. It is also noted that the optical vortex is well confined in the space-time domain, and preserves intact spiral wavefront structure and conserved topological charge. What’s more, the transverse energy flow rotates periodically, and the central irradiance increases continuously when increase the propagation distance. Our work realized the separation and combination of the intertwined time and space variables, and further revealed the propagation dynamics of spatiotemporal structured light fields.