Optical strong coupling in hybrid metal-graphene metamaterial for terahertz sensing*

Abstract

We propose a terahertz hybrid metamaterial composed of subwavelength metallic slits and graphene plasmonic ribbons for sensing application. This special design can cause the interaction between the plasmon resonances of the metallic slits and graphene ribbons, giving rise to a strong coupling effect and Rabi splitting. Intricate balancing in the strong coupling region can be perturbed by the carrier concentration of graphene, which is subject to the analyte on its surface. Thereby, the detection of analyte can be reflected as a frequency shift of resonance in terahertz transmission spectra. The result shows that this sensor can achieve a theoretical detection limit of 325 electrons or holes per square micrometer. Meanwhile, it also works well as a refractive index sensor with the frequency sensitivity of 485 GHz/RIU. Our results may contribute to design of ultra-micro terahertz sensors.

Graphene-based tunable tri-band terahertz refractive index sensor

“…During the intra-band transition process, scattering occurs between electrons and photons in graphene, resembling the Drude dispersion effect. The surface conductivity model of graphene can be simplified using the Drude model, 21 as shown in Eq. ( 2):…”