Nonreciprocal transmission in a cavity-magnon system by rotational Sagnac effect

TL;DR

This paper demonstrates ultrahigh nonreciprocal optical transmission in a cavity-magnon system using the Sagnac effect, achieving record isolation ratios and tunability through rotation and magnon squeezing.

Contribution

It introduces a novel cavity-magnon system leveraging the Sagnac effect for highly tunable nonreciprocal transmission with record isolation ratios.

Findings

Isolation ratio exceeds 40 dB.

Nonreciprocal transmission can be reversed by changing cavity rotation.

Magnon squeezing enhances isolation performance.

Abstract

Ultrahigh nonreciprocal transmission has been achieved in a cavity-magnon system, which consists of two whispering gallery modes (WGMs) and a single magnon mode within a magnetic insulator yttrium iron garnet sphere. The nonreciprocal frequency shift induced by the Sagnac effect enables unidirectional transmission of an input field, while suppressing propagation in the opposite direction, thereby facilitating nonreciprocal optical transmission. Within experimentally accessible parameter regimes, the optical isolation ratio can exceed 40 dB, representing the highest isolation ratio reported to date. Furthermore, applying squeezing to the magnon mode further enhances this isolation performance. Additionally, the directionality of light isolation can be reversed simply by modifying the rotation of the WGM cavity. These findings offer promising prospects for developing high-performance, tunable, and compact optical nonreciprocal devices.