Comparison of gold- and graphene-based resonant nanostructures for terahertz metamaterials and an ultrathin graphene-based modulator

Abstract

Graphene exhibits unique material properties and in electromagnetic wave technology, it raises the prospect of devices miniaturized down to the atomic length scale. Here we study split-ring resonator metamaterials made from graphene and we compare them to gold-based metamaterials.We find that graphene's huge reactive response derived from its large kinetic inductance allows for deeply subwavelength resonances, although its resonance strength is reduced due to higher dissipative loss damping and smaller dipole coupling. Nevertheless, tightly stacked graphene rings may provide for negative permeability and the electric dipole resonance of graphene meta-atoms turns out to be surprisingly strong. Based on these findings, we present a terahertz modulator based on a metamaterial with a multi-layer stack of alternating patterned graphene sheets separated by dielectric spacers. Neighbouring graphene flakes are biased against each other, resulting in modulation depths of over 70% at a transmission level of around 90%.

Broadband, Spectrally Flat, Graphene‐based Terahertz Modulators

“…Its tunable graphene carrier concentration, controllable by electrical gating or externally applied electric and/or magnetic fields, makes graphene an ideal candidate for use in terahertz modulators. Several terahertz modulators benefitting from graphene for improved performance have been proposed and investigated . One class of such modulators are graphene‐based metamaterial modulators, combining an active graphene layer with a metamaterial structure to modulate both the amplitude and phase of a transmitted or reflected wave.…”

“…Several terahertz modulators benefitting from graphene for improved performance have been proposed and investigated . One class of such modulators are graphene‐based metamaterial modulators, combining an active graphene layer with a metamaterial structure to modulate both the amplitude and phase of a transmitted or reflected wave. However, the exceptional control over terahertz waves in graphene‐metamaterial hybrid modulators can only be achieved at frequencies close to the intrinsic metamaterial resonance.…”

Large optical anisotropy for terahertz light of stacked graphene ribbons with slight asymmetry

“…Similarly, a split ring resonator made of graphene can be much smaller than one made of Au, as shown in the previous report. 27 …”

Tailoring Active Far-Infrared Resonator with Graphene Metasurface and Its Complementary

“…Among them, active device is critical for real-time high-speed manipulation of far-infrared or terahertz waves. In many studies, split rings have become a central element from far-infrared to near-infrared because of its large magnetic response driven by the circular current and produce fascinating optical properties, such as superresolution imaging, cloaking, and sensing [7][8][9][10]. Graphene, a monolayer carbon atom arranged in honeycomb structures, is a promising candidate for this application because of its electrically tunable properties and low loss in comparison with metals working at far-infrared frequencies [11][12][13][14].…”