Terahertz range resonances of metasurface formed by double-layer grating of microsize graphene strips inside dielectric slab

Abstract

We analyse, using integral equations and a previously developed in-house numerical algorithm, the scattering and absorption of the H -polarized plane wave by a metasurface consisting of a double-layer grating of flat graphene strips placed into a lossless dielectric slab. The algorithm is meshless and its convergence is guaranteed mathematically. It is a version of the method of analytical preconditioning; namely, it uses the set of weighted Chebyshev polynomials as expansion functions in the discretization of a hypersingular electric field integral equation for the on-strip current. Then the computational error is controlled by the matrix size and can be reduced to machine precision. Using this advanced tool, we plot the frequency dependences, in a huge range from 1 GHz to 10 THz, of the transmittance, reflectance and absorbance of such a metasurface. This accurate analysis reveals resonances on several types of natural modes, best understood via visualization of in-resonance near-fields. In addition to plasmon-mode resonances, special attention is paid to the ultra-high- Q resonances on the lattice modes, which are absent on the free-standing graphene strip gratings.

Scattering of the H-polarized plane wave by finite and semi-infinite multilayer systems of infinite graphene strip gratings in the THz range

“…To validate our results we compare them with results obtained by MAR [19] in the case of double-layer-graphene grating embedded into one dielectric slab, i.e. for 2 h = L , M = 2.…”

“…In [18], the graphene infinite strip grating (ISG) embedded into a dielectric slab is considered with the use of the method of analytical regularization (MAR). In a subsequent paper [19], the double-layer system is studied.…”

A theoretical design of evanescent wave biosensors based on gate-controlled graphene surface plasmon resonance

“…Through the electromagnetic wave coupling between photon and plasmon, the excitation of SPPs (surface plasmon polaritons) is present with its field exponentially decaying (evanescent wave) along the direction perpendicular to the surface 4 – 9 . Additionally, enhanced absorption of surface plasmons on a periodic array of graphene ribbons for TM-polarization (the magnetic field is along the ribbon axis) was reported 10 – 13 . Specifically, the obvious optical absorption due to the SPR on graphene ribbons, particularly on its fundamental resonant mode, was demonstrated 10 .…”

Excitation of guided waves of grounded dielectric slab by a THz plane wave scattered from finite number of embedded graphene strips: Singular integral equation analysis

“…Inside the dielectric slab additional resonances can arise. Slab-mode and grating or lattice-mode resonances are studied in [7,20,21] with the help of SIE and regularising method of moments (MoM).…”

“…Approximate techniques can describe only basic physical effects in much less computation time [8,29]. In contrast, rigorous meshless methods such as SIEs combined with the method of analytical regularisation (MAR), regularising Galerkin MoM or Nystrom discretisation provide results with controllable accuracy up to machine precision within a reasonable time [7,11,14,17,19,20,30].…”