Using High-k VPP Modes in Grating-Coupled Graphene-Based Hyperbolic Metamaterial for Tunable Sensor Design

Abstract

Volume plasmon polariton (VPP), a high-k mode that arises due to the coupling between two even modes of adjacent layers of an hyperbolic metamaterial (HMM) configuration, is very difficult to be excited by using prism coupling technique due to huge wave-vector mismatch. In this work, we present a graphene-based HMM structure integrated with metal grating to facilitate excitation of VPP modes. A graphene HMM is composed of multilayer graphene super-lattice similar to metal-dielectric super-lattice structure. We report the analytical formulation of the dispersion relation and numerical results of the characteristics of the excited VPP modes for the proposed structure in the Terahertz region of the spectrum. The best achieved imaging resolution of our proposed structure is 15 nm when used as an infra-red imaging platform. As a sensing platform, a maximum sensitivity of 11,050 nm/RIU is achieved for this configuration. The tunability of the resonance wavelength with respect to the structural parameters of the device is also studied and confirmed. Such promising findings are expected to make the proposed structure with integrated excitation coupler a potential candidate for tunable sensor design for different nanophotonic applications, including imaging, and, biomedical and chemical sensing applications.