Graphene-based tunable hyperbolic metamaterials and enhanced near-field absorption

Abstract

Abstract:We investigate a novel implementation of hyperbolic metamaterial (HM) at far-infrared frequencies composed of stacked graphene sheets separated by thin dielectric layers. Using the surface conductivity model of graphene, we derive the homogenization formula for the multilayer structure by treating graphene sheets as lumped layers with complex admittances. Homogenization results and limits are investigated by comparison with a transfer matrix formulation for the HM constituent layers. We show that infrared iso-frequency wavevector dispersion characteristics of the proposed HM can be tuned by varying the chemical potential of the graphene sheets via electrostatic biasing. Accordingly, reflection and transmission properties for a film made of graphene-dielectric multilayer are tunable at terahertz frequencies, and we investigate the limits in using the homogenized model compared to the more accurate transfer matrix model. We also propose to use graphene-based HM as a super absorber for near-fields generated at its surface. The power emitted by a dipole near the surface of a graphene-based HM is increased dramatically (up to 5 × 10 2 at 2 THz), furthermore we show that most of the scattered power is directed into the HM. The validity and limits of the homogenized HM model are assessed also for near-fields and show that in certain conditions it overestimates the dipole radiated power into the HM.

Self-biased reconfigurable graphene stacks for terahertz plasmonics

“…The exotic characteristics of graphene stacks paves the way towards the development of a low-dimensional plasmonic platform with enhanced performance and reconfiguration capabilities. For instance, graphene stacks are the building block of the recently proposed tunable bulk hyperbolic metamaterials 50 , whereas it has also demonstrated that they are able to boost the spontaneous emission of emitters 51 much further than the usual monolayer graphene structures 1 . In a different context, the large range of imaginary conductivity values provided by the stacks can easily be exploited in planar hyperlenses.…”

Dual-gated tunable absorption in graphene-based hyperbolic metamaterial

“…If ε xx ε zz <0, the dispersive curve is hyberbolic, and for ε xx ε zz >0, it is elliptic. 6,22,32 Absorption was then calculated as a function of frequency and incident angle for electromagnetic waves in a semi-infinite slab of material. The transfer matrix method used was previously reported.…”

“…Numerous reports have focused on how to enhance the absorption of graphene and other materials at optical, infrared, and terahertz frequency regimes. [20][21][22] sheets separated by thin dielectric layers. This shows that graphene-based HMM (GHMMs) can be used as super absorbers for near-field applications.…”

“…The use of GHMM as a thin absorber results in critical coupling in the near-infrared frequency range, with one or two nearly perfect peaks. 22 However, to the author's knowledge, limited research has been performed on GHMM dual-gated absorbers.…”

Tunable Metamaterials Made of Graphene-Liquid Crystal Multilayers

“…Iorsh et al suggested a kind of hyperbolic MMs where individual graphene sheets are separated by host dielectric slabs and demonstrated a possibility of tuning the dispersion properties of the MM with external electric and magnetic fields [24]. The tunability of the reflection and transmission properties of a film made of graphene-dielectric multilayer structure at THz frequencies have been investigated by Othman et al [25].…”