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

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.