Interferometric control of magnon-induced nearly perfect absorption in cavity magnonics

J W Rao,D S Xue,Bimu Yao,Y Yang,X L Fan,P C Xu,Y S Gui,J Dietrich,Y P Wang,G E Bridges,C.-M Hu

doi:10.1038/s41467-021-22171-7

J W Rao, D S Xue + Show 9 more

Open Access

https://doi.org/10.1038/s41467-021-22171-7

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Abstract

The perfect absorption of electromagnetic waves has promoted many applications, including photovoltaics, radar cloaking, and molecular detection. Unlike conventional methods of critical coupling that require asymmetric boundaries or coherent perfect absorption that require multiple coherent incident beams, here we demonstrate single-beam perfect absorption in an on-chip cavity magnonic device without breaking its boundary symmetry. By exploiting magnon-mediated interference between two internal channels, both reflection and transmission of our device can be suppressed to zero, resulting in magnon-induced nearly perfect absorption (MIPA). Such interference can be tuned by the strength and direction of an external magnetic field, thus showing versatile controllability. Furthermore, the same multi-channel interference responsible for MIPA also produces level attraction (LA)-like hybridization between a cavity magnon polariton mode and a cavity photon mode, demonstrating that LA-like hybridization can be surprisingly realized in a coherently coupled system.

Highlights

The perfect absorption of electromagnetic waves has promoted many applications, including photovoltaics, radar cloaking, and molecular detection
The single-beam absorption of a resonant mode with a symmetric boundary never goes beyond 50%8–11 (Fig. 1a, details in supplementary Note 1). This reflects a common limitation shared by planar plasmas[8], qubits[9], graphene[10], and thin films[11], which can be generally abstracted into a symmetric two-port system
In a cavity magnonic system, microwave photons couple to magnons and evolve into quasiparticles called cavity magnon polaritons (CMPs)[23], whose hybridization, dispersion, and damping rates can be flexibly tailored by harnessing the magnon dynamics in solids

Summary

Introduction

The perfect absorption of electromagnetic waves has promoted many applications, including photovoltaics, radar cloaking, and molecular detection. The single-beam absorption of a resonant mode with a symmetric boundary never goes beyond 50%8–11 (Fig. 1a, details in supplementary Note 1). We demonstrate that single-beam nearly perfect absorption can be achieved within a multi-port cavity magnonic device by exploiting the interference between its tunable internal channels (polariton modes).

Results

Conclusion