Perfect space-time vortices

We introduce the concept of perfect space-time vortices (PSTVs) that can exist in media with anomalous dispersion. If the topological charge of a PSTV is not too large, the spatiotemporal intensity distribution of the vortex field does not depend on the magnitude of the topological charge. We show theoretically how a PSTV can be realized in the optical context through spatiotemporal focusing of a Bessel-Gaussian space-time optical vortex source that is placed in the focal plane of a space-time lens composed of an ordinary lens and a time lens with matched spatial and temporal focal lengths.