Building blocks for space-time non-separable pulses

TL;DR

This paper demonstrates how space-time non-separable pulses, important for advanced optical applications, can be constructed from simple wave components, with analytical expressions provided for the flying doughnut pulse.

Contribution

It provides the first analytical framework for synthesizing space-time non-separable pulses from basic wave sources like plane waves and monochromatic beams.

Findings

Analytical expressions for the flying doughnut pulse.

Construction of non-separable pulses from simple waves.

Potential for experimental generation of complex pulses.

Abstract

Space-time non-separable pulses hold promise for topological information transfer, probing ultra-fast light-matter interactions and engaging toroidal excitations in matter. Spurred by recent advances in ultra-fast and topological optics, these exotic electromagnetic excitations are now becoming the focus of growing experimental efforts. Many practical questions are yet to be answered regarding their generation, detection and light matter interactions. In particular, can these pulses be constructed from plane waves or other simple but experimentally accessible waves? Here we demonstrate that they can and as an example we provide analytical expressions for the characteristic case of the flying doughnut pulse which allows the expansion and synthesis of the pulse from sets of monochromatic beams, single-cycle pulses, and plane waves.