Toroidal helical pulses

TL;DR

This paper introduces a new family of toroidal helical electromagnetic pulses with controllable helicity, combining theoretical modeling and experimental realization using a coaxial horn and spiral grating, opening avenues for advanced light-matter interactions.

Contribution

It presents the first theoretical framework and experimental method to generate and control toroidal helical pulses with non-transverse topology.

Findings

Successful experimental generation of toroidal helical pulses.

Pulses exhibit controllable helicity and space-time nonseparability.

Paves the way for novel applications in light-matter interactions.

Abstract

Toroidal topologies and helicity are pervasive in nature and hold basic importance in scientific research. In particular, the interplay between these features gives rise to fascinating toroidal helical electromagnetic excitations. Here, we present a theoretical framework and experimental realization to introduce a family of toroidal helical pulses, exploring the intersection of the helicity and propagating toroidal modes. For this purpose, we propose a configuration combining a coaxial horn emitter and an equiangular spiral grating to directly generate such single-cycle pulses. In addition to their inherent non-transverse toroidal topology and space-time nonseparability, such pulses also possess controllable helicity. This work gives rise to a helical version of propagating toroidal electrodynamics, thereby paving the way for advanced applications, such as nontrivial light-matter interactions and data transfer.