Tailoring far-infrared surface plasmon polaritons of a single-layer graphene using plasmon-phonon hybridization in graphene-LiF heterostructures

Abstract

Being one-atom thick and tunable simultaneously, graphene plays the revolutionizing role in many areas. The focus of this paper is to investigate the modal characteristics of surface waves in structures with graphene in the far-infrared (far-IR) region. We discuss the effects exerted by substrate permittivity on propagation and localization characteristics of surface-plasmon-polaritons (SPPs) in single-layer graphene and theoretically investigate characteristics of the hybridized surface-phonon-plasmon-polaritons (SPPPs) in graphene/LiF/glass heterostructures. First, it is shown how high permittivity of substrate may improve characteristics of graphene SPPs. Next, the possibility of optimization for surface-phonon-polaritons (SPhPs) in waveguides based on LiF, a polar dielectric with a wide polaritonic gap (Reststrahlen band) and a wide range of permittivity variation, is demonstrated. Combining graphene and LiF in one heterostructure allows to keep the advantages of both, yielding tunable hybridized SPPPs which can be either forwardly or backwardly propagating. Owing to high permittivity of LiF below the gap, an almost 3.2-fold enhancement in the figure of merit (FoM), ratio of normalized propagation length to localization length of the modes, can be obtained for SPPPs at 5–9 THz, as compared with SPPs of graphene on conventional glass substrate. The enhancement is efficiently tunable by varying the chemical potential of graphene. SPPPs with characteristics which strongly differ inside and around the polaritonic gap are found.

Mapping Phonon Polaritons with Visible Light

“…Assessing the promise of PhP modes as mid-IR emitters clearly requires an investigation of the interactions between electrons, phonons, and PhP modes. Studies on PhP-ZFLO 7 and PhP-electron 4,19 interactions have been very important in this regard however, full explorations of bulk phonon-PhP-electron coupling have remained limited. Practical challenges have played a role in this delay.…”

“…Practical challenges have played a role in this delay. Investigations of PhPs in dielectric nanostructures have increasingly revealed strong spatial dependence on light-matter interactions -for example, the strength of electron-phonon coupling in many nanostructures depends on the induced 3D charge distribution 4,19,20 . Therefore, any investigation into light-matter coupling would ideally demonstrate how the full 3D PhP eigenmodes interact with solid state excitations to be complete.…”

Design of a High-Gain and Tri-Band Terahertz Microstrip Antenna Using a Polyimide Rectangular Dielectric Column Photonic Band Gap Substrate

“…Hajian et.al discusses the effects exerted by different substrates' permittivity on the propagation and localization characteristics of surface plasmon polaritons (SPPs) in single-layer graphene. However, the substrate material can affect the transmission characteristics of graphene and have an impact on antenna performance [19]. Li et al investigated the effect of changing the properties of nearby substrates on the propagation distance of plasma.…”

Towards Perfect Absorption of Single Layer CVD Graphene in an Optical Resonant Cavity: Challenges and Experimental Achievements

“…In the THz and IR regions, however, high quality graphene may show strong interaction with light thanks to generation of surface plasmon polaritons (SPPs), making graphene a promising alternative to typical plasmonic materials [ 22 , 23 , 24 , 25 ]. This is thanks to the capability of graphene to support plasmon modes with extremely tight confinement, long lifetime, and low losses at IR and THz frequencies [ 26 , 27 , 28 , 29 ].…”