Coupled states of electromagnetic fields with magnetic-dipolar-mode vortices: MDM-vortex polaritons

TL;DR

This paper investigates MDM-vortex polaritons, revealing their unique helicity behaviors and topological field structures, with potential applications in microwave metamaterials and near-field sensing.

Contribution

It introduces and analyzes the properties of MDM-vortex polaritons, a new type of coupled electromagnetic-magnetic excitation state in ferrite disks.

Findings

MDM-vortex polaritons exhibit distinct helicity behaviors.

Frequency splits lead to localization or cloaking of fields.

Topological structures of the fields are numerically characterized.

Abstract

Under the influence of the material environment, electromagnetic fields in the near-field regime exhibit quite different nature from those in the far-field free space. A coupled state of an electromagnetic field with an electric or magnetic dipole-carrying excitation is well known as a polariton. Such a state is the result of the mixing of a photon with an excitation of a material. The most discussed types of polaritons are phonon-polaritons, exciton-polaritons, and surface plasmon-polaritons. Recently, it was shown that in microwaves strong magnon-photon coupling can be achieved due to magnetic-dipolar-mode (MDM) vortices in small thin-film ferrite disks. These coupled states can be specified as MDM-vortex polaritons. In this paper we study properties of MDM-vortex polaritons. We show that MDM-vortex polaritons are characterized by helicity behaviors. For the observed frequency splits of MDM resonances there are different-type helicities. In the split-resonance states one has or localization, or cloaking of electromagnetic fields. We analyze numerically a variety of the field topological structures of MDM-vortex polaritons and give theoretical insights into the possible origin of such topologically distinctive states. The shown properties of MDM-vortex polaritons can be useful for realization of novel microwave metamaterial structures and near-field sensing applications.