Focused electromagnetic doughnut pulses and their interaction with interfaces and nanostructures

TL;DR

This paper investigates the propagation and interaction of focused electromagnetic doughnut pulses, revealing their reflection, refraction, and ability to excite toroidal dipoles in dielectric particles, advancing understanding of complex light-matter interactions.

Contribution

It provides new insights into the behavior of focused doughnut pulses at interfaces and their capacity to induce toroidal dipoles, a novel aspect of electromagnetic pulse interactions.

Findings

Reflections and refractions cause complex field distortions.

Conditions for exciting toroidal dipoles are identified.

Enhanced understanding of light-matter interactions with toroidal topology.

Abstract

We study the propagation properties and light-matter interactions of the focused doughnut pulses, broadband, single-cycle electromagnetic perturbations of toroidal topology first described by Hellwarth and Nouchi in 1996. We show how focused doughnuts are reflected and refracted at planar metallic and vacuum-dielectric interfaces leading to complex distortions of the field structure. We also identify the conditions under which these toroidal pulses excite dominant dynamic toroidal dipoles in spherical dielectric particles.