Triple-resonant Brillouin light scattering in magneto-optical cavities

TL;DR

This paper demonstrates enhanced Brillouin light scattering in magneto-optical whispering gallery resonators at a triple resonance point, enabling efficient optical-microwave conversion through mode matching and sideband suppression.

Contribution

It introduces a novel triple-resonance condition in magneto-optical cavities that enhances Brillouin scattering and enables selective sideband excitation for improved frequency conversion.

Findings

Enhanced Brillouin scattering observed at triple resonance

Mode-matching conditions clarified for optimal excitation

Single-sideband excitation achieved with wavevector matching

Abstract

An enhancement in Brillouin light scattering of optical photons with magnons is demonstrated in magneto-optical whispering gallery mode resonators tuned to a triple resonance point. This occurs when both the input and output optical modes are resonant with those of the whispering gallery resonator, with a separation given by the ferromagnetic resonance (FMR) frequency. The identification and excitation of specific optical modes allows us to gain a clear understanding of the mode-matching conditions. A selection rule due to wavevector matching leads to an intrinsic single-sideband excitation. Strong suppression of one sideband is essential for one-to-one frequency mapping in coherent optical-to-microwave conversion.