Tunable Graphene Split-Ring Resonators

TL;DR

This paper demonstrates tunable graphene split-ring resonators with deep subwavelength magnetic responses in the terahertz range, showing potential for advanced graphene-based metamaterials.

Contribution

First experimental realization of graphene split-ring resonators exhibiting magnetic dipole responses and tunability, advancing graphene metamaterials beyond simple structures.

Findings

Deep subwavelength magnetic dipole response achieved

Resonances tunable via doping and stacking

Strong substrate interaction influences response

Abstract

A split-ring resonator is a prototype of meta-atom in metamaterials. Though noble metal-based split-ring resonators have been extensively studied, up to date, there is no experimental demonstration of split-ring resonators made from graphene, an emerging intriguing plasmonic material. Here, we experimentally demonstrate graphene split-ring resonators with deep subwavelength (about one hundredth of the excitation wavelength) magnetic dipole response in the terahertz regime. Meanwhile, the quadrupole and electric dipole are observed,depending on the incident light polarization. All modes can be tuned via chemical doping or stacking multiple graphene layers. The strong interaction with surface polar phonons of the SiO2 substrate also significantly modifies the response. Finite-element frequency domain simulations nicely reproduce experimental results. Our study moves one stride forward toward the multi-functional graphene metamaterials, beyond simple graphene ribbon or disk arrays with electrical dipole resonances only.