Enhanced transmission with a graphene-dielectric microstructure at low-terahertz frequencies

Abstract

Here, we report on the transmissivity of electromagnetic waves through a stack of monolayer graphene sheets separated by dielectric slabs at low-terahertz frequencies. It is observed that the multilayer structure possesses band-gap properties and supports a series of bandpass and band-stop regions, similar to the cases of stacked metallic meshes separated by dielectric slabs at microwave/THz frequencies and a metal-dielectric stack at optical frequencies. The transmission resonances in the bandpass region are identified as coupled Fabry-Pérot resonances associated with the individual cavities of dielectric slabs loaded with graphene sheets. It is also noticed that these resonances lie within a certain characteristic frequency band, independent of the number of layers in the graphene-dielectric stack. The study is carried out using a simple analytical transfer-matrix approach or, equivalently, a circuit-theory model, resulting in the exact solution for the multiple dielectric/graphene sheet surface-conductivity model. Also, an independent verification of the observed phenomena is obtained with commercial numerical simulations.

Dual capacitive-inductive nature of periodic graphene patches: Transmission characteristics at low-terahertz frequencies

“…Alternatively, one can use the circuit model described in Refs. 12,13, and 46 to analyze the multilayer stack with the graphene patches modeled as a shunt admittance (Y s = 1/Z s ) across the transmission-line sections.…”

“…12 that the stacked metallic apertures/mesh-grids at microwave frequencies mimic the transmission properties of a metal-dielectric stack at optical frequencies, and in Ref. 9 it was shown that a graphene sheetdielectric stack at low-terahertz frequencies behaves similar to metallic apertures/mesh-grids. In general, metal patch structures have a capacitive surface reactance, and exhibit a low-frequency passband followed by alternating stop and (generally poorer quality) passbands as frequency increases [see Fig.…”

“…In this work, we continue our study of transmission properties of a graphene-dielectric stack at low-terahertz frequencies, 9 with the graphene monolayers replaced by twodimensional (2D) periodic graphene patches (with a typical geometry shown in Fig. 1).…”

“…For example, these include a stack of metal apertures (mesh-grids) at microwave 12 and infrared frequencies, 5,6 a stack of metallic patch arrays at microwave frequencies, 13 metal-dielectric and aperture/mesh-grid-dielectric stacks at optical frequencies, [1][2][3][4] and more recently a stack of graphene sheets-dielectric layers at low-terahertz frequencies. 9 Various periodically patterned graphene surfaces [14][15][16][17][18] have been designed at microwave, terahertz, and optical frequencies for tunable metamaterials, with potential applications including filters, absorbers, and polarizers. Of particular interest is the low-terahertz band which has seen an increase in graphene applications (e.g., cloaking 19 and plasmonic oscillators, 20 among others) due to the low real part of its surface conductivity, forming a low-loss surface reactance.…”

“…With the latest developments in fabrication technology, the transmission and reflection spectra of these structures can be realized at optical, [1][2][3][4] infrared, 5,6 terahertz, [7][8][9] and microwave [10][11][12][13] frequencies through careful design of the constituent subwavelength periodic elements and dielectric layers. For example, these include a stack of metal apertures (mesh-grids) at microwave 12 and infrared frequencies, 5,6 a stack of metallic patch arrays at microwave frequencies, 13 metal-dielectric and aperture/mesh-grid-dielectric stacks at optical frequencies, [1][2][3][4] and more recently a stack of graphene sheets-dielectric layers at low-terahertz frequencies. 9 Various periodically patterned graphene surfaces [14][15][16][17][18] have been designed at microwave, terahertz, and optical frequencies for tunable metamaterials, with potential applications including filters, absorbers, and polarizers.…”