Propagation dynamics of a spatiotemporal vortex pulse in the spatial fractional system

Abstract

The dynamics of wave packets carrying a spatiotemporal vortex in the spatial fractional system is still an open problem. The difficulty stems from the fact that the fractional Laplacian derivative is essentially a nonlocal operator, and the vortex is space-time coupled. Here, we investigate the transmission of spatiotemporal vortices in the spatial fractional wave equation (FWE) and demonstrate the effects of linewidth, vortex topological charge, and linear chirp modulation on the transmission of Bessel-type spatiotemporal vortex pulses (BSTVPs). Under narrowband conditions, we find that the propagation of BSTVP in the FWE can be seen as the coherent superposition of two linearly shifted half-BSTVPs and can reveal orbital angular momentum backflow for the half-BSTVP. Our analysis can be extended to other spatiotemporal vortex pulses.