Magneto-optical coupling in whispering gallery mode resonators

TL;DR

This paper demonstrates magneto-optical coupling in yttrium iron garnet microspheres supporting whispering gallery modes, revealing how magnetic orientation influences optical properties, which is key for advancing cavity optomagnonics.

Contribution

It provides the first experimental demonstration of magneto-optical effects in whispering gallery mode resonators made of magnetic materials.

Findings

Magnetic field tunes resonant frequency via Voigt effect.

Magnetization affects polarization rotation through Faraday effect.

Supports development of cavity optomagnonics applications.

Abstract

We demonstrate that yttrium iron garnet microspheres support optical whispering gallery modes similar to those in non-magnetic dielectric materials. The direction of the ferromagnetic moment tunes both the resonant frequency via the Voigt effect as well as the degree of polarization rotation via the Faraday effect. An understanding of the magneto-optical coupling in whispering gallery modes, where the propagation direction rotates with respect to the magnetization, is fundamental to the emerging field of cavity optomagnonics.