Circular displacement current induced anomalous magneto-optical effects in high index Mie resonators

TL;DR

This paper reports the discovery of anomalous magneto-optical effects in high-index Mie resonators caused by circular displacement currents, enabling enhanced light modulation and polarization control for advanced photonic applications.

Contribution

It introduces a novel mechanism of circular displacement current-induced magneto-optical effects in dielectric Mie resonators, expanding the understanding of light-matter interactions at the nanoscale.

Findings

Giant light intensity modulation up to 6.4% in transverse magnetic configuration.

Large polarization rotation two orders of magnitude higher than planar films.

Effects originate from circular displacement currents in magnetic resonance modes.

Abstract

Dielectric Mie nanoresonators showing strong light-matter interaction at the nanoscale may enable new functionality in photonic devices. Recently, strong magneto-optical effects have been observed in magneto-optical nanophotonic devices due to the electromagnetic field localization. However, most reports so far have been focused on the enhancement of conventional magneto-optical effects. Here, we report the observation of circular displacement current induced anomalous magneto-optical effects in high-index-contrast Si/Ce:YIG/YIG/SiO2 Mie resonators. In particular, giant modulation of light intensity in transverse magnetic configuration up to 6.4 % under s-polarized incidence appears, which is non-existent in planar magneto-optical thin films. Apart from that, we observe a large rotation of transmitted light polarization in the longitudinal magnetic configuration under near normal incidence conditions, which is two orders of magnitude higher than for a planar magneto-optical thin film. These phenomena are essentially originated from the unique circular displacement current when exciting the magnetic resonance modes in the Mie resonators, which changes the incident electric field direction locally. Our work indicates an uncharted territory of light polarization control based on the complex modal profiles in all-dielectric magneto-optical Mie resonators and metasurfaces, which opens the door for versatile control of light propagation by magnetization for a variety of applications in vectoral magnetic field and biosensing, free space non-reciprocal photonic devices, magneto-optical imaging and optomagnetic memories.