Optomagnonic whispering gallery microresonators

TL;DR

This paper demonstrates high-quality optomagnonic whispering gallery microresonators in YIG spheres, enabling efficient magnon-mediated microwave-to-optical conversion through triply resonant scattering.

Contribution

It introduces a novel optomagnonic cavity with high-Q whispering gallery modes in YIG spheres, facilitating coherent magnon-photon interactions for microwave-to-optical conversion.

Findings

Achieved near 10^6 quality factors in YIG sphere resonators.

Demonstrated polarization-selective Brillouin scattering in the cavity.

Showed potential for microwave-to-optical signal conversion.

Abstract

Magnons in ferrimagnetic insulators such as yttrium iron garnet (YIG) have recently emerged as promising candidates for coherent information processing in microwave circuits. Here we demonstrate optical whispering gallery modes of a YIG sphere interrogated by a silicon nitride photonic waveguide, with quality factors approaching $10^6$ in the telecom c-band after surface treatments. Moreover, in contrast to conventional Faraday setup, this implementation allows input photon polarized colinearly to the magnetization to be scattered to a sideband mode of orthogonal polarization. This Brillouin scattering process is enhanced through triply resonant magnon, pump and signal photon modes - all of whispering gallery nature - within an "optomagnonic cavity". Our results show the potential use of magnons for mediating microwave-to-optical carrier conversion.