Tunable Graphene Split-Ring Resonators

Graphene plasmonics, allowing strong light-matter interactions, subwavelength light confinement and in situ tunability, has gained much attention due to the potential to develop new optoelectronic and photonic devices. Here, we experimentally demonstrate graphene split ring resonators with deep subwavelength confined magnetic dipole, quadrupole and electric dipole responses in terahertz regime. All modes can be tuned via chemical doping or stacking multiple graphene layers. Finite-element frequency domain simulations nicely reproduce experimental results. Our study demonstrates an example of tunable multiple resonances based on graphene, and shed new light on its application in tunable high-frequency magnetic metasurfaces.