Switching terahertz waves with gate-controlled active graphene metamaterials

Abstract

The extraordinary electronic properties of graphene provided the main thrusts for the rapid advance of graphene electronics. In photonics, the gate-controllable electronic properties of graphene provide a route to efficiently manipulate the interaction of photons with graphene, which has recently sparked keen interest in graphene plasmonics. However, the electro-optic tuning capability of unpatterned graphene alone is still not strong enough for practical optoelectronic applications owing to its non-resonant Drude-like behaviour. Here, we demonstrate that substantial gate-induced persistent switching and linear modulation of terahertz waves can be achieved in a two-dimensional metamaterial, into which an atomically thin, gated two-dimensional graphene layer is integrated. The gate-controllable light-matter interaction in the graphene layer can be greatly enhanced by the strong resonances of the metamaterial. Although the thickness of the embedded single-layer graphene is more than six orders of magnitude smaller than the wavelength (<λ/1,000,000), the one-atom-thick layer, in conjunction with the metamaterial, can modulate both the amplitude of the transmitted wave by up to 47% and its phase by 32.2° at room temperature. More interestingly, the gate-controlled active graphene metamaterials show hysteretic behaviour in the transmission of terahertz waves, which is indicative of persistent photonic memory effects.

Self-biased reconfigurable graphene stacks for terahertz plasmonics

“…The characterization of single-layer graphene structures has already been done for microwaves [4][5][6][7] , THz 7-9 and optics 3,10 , and some promising applications such as modulators [11][12][13][14][15][16] , plasmonic waveguides 17,18 and Faraday rotators 19 have been developed. However, the simple implementation and performance of these devices might be hindered by the presence of a gating electrode located close to graphene and the relatively weak control that this approach offers over the conductivity of graphene 11,20 .…”

Optically controlled terahertz filter based on graphene and cross-like metasurface

“…The frequency of graphene plasma waves lies in the terahertz range [6], making graphene appealing for controllable terahertz devices such as modulators and filters, where the resonant frequency can be tuned by an external electric field or optical pumping. In recent research, various hybrid structures based on graphene/metamaterial were proposed, and their optical parameters were controlled by application of a bias voltage between metamaterial and graphene [7][8][9][10][11] or by optical pumping in the infrared frequency range [12]. The central resonant frequency for such devices depended on the geometrical parameters of unit cell and the conductivity of graphene [8].…”

Tunable Metamaterials Made of Graphene-Liquid Crystal Multilayers

“…At the frequency ranges of THz and far-infrared, the dissipative loss of graphene is less than the usual metals and its optical response is described by the surface conductivity which is related to its chemical potential and can be controlled and tuned by voltage or chemical doping [16][17][18]. Graphene-based liquid crystal devices, optical modulators and switches can be mentioned as examples [19][20][21][22]. Also, the optical properties and some applications of the multilayer graphene structures have been investigated by different research groups.…”