High-Contrast Terahertz Wave Modulation by Gated Graphene Enhanced by Extraordinary Transmission through Ring Apertures

Abstract

Gate-controllable transmission of terahertz (THz) radiation makes graphene a promising material for making high-speed THz wave modulators. However, to date, graphene-based THz modulators have exhibited only small on/off ratios due to small THz absorption in single-layer graphene. Here we demonstrate a ∼50% amplitude modulation of THz waves with gated single-layer graphene by the use of extraordinary transmission through metallic ring apertures placed right above the graphene layer. The extraordinary transmission induced ∼7 times near-filed enhancement of THz absorption in graphene. These results promise complementary metal-oxide-semiconductor compatible THz modulators with tailored operation frequencies, large on/off ratios, and high speeds, ideal for applications in THz communications, imaging, and sensing.

Active 2D materials for on-chip nanophotonics and quantum optics

“…Here, we reviewed a subset of applications: optical interconnect technologies including high-speed photodetectors [15,16,39] and modulators [10,13], as well as device concepts for photonic quantum information processing, including progress toward efficient single photon sources and single photon detectors. With the exceptional progress of the past decade, such a scalable 2D nanophotonic architecture could bring remarkable impacts for these applications in the near future, while promising other directions including back-end deposited silicon photonics [118], mid-infrared photonics [119], THz detection [120,121] and modulation [122], and also flexible photonics [123].…”

Graphene-based electrically reconfigurable deep-subwavelength metamaterials for active control of THz light propagation

“…[10]). For comparison, the active area to unit cell area ratio of previously proposed graphene active terahertz metamaterials lies between 50 and 100 % (e.g., [12][13][14][15]18]) with reported switching in the order of 10 kHz (e.g., Ref. [10,20]); via reducing the Active control of THz light propagation active area switching speeds associated with GHz frequencies can be attained.…”

“…An active graphene layer is placed in the center of each unit cell; its electromagnetic properties and therefore the effective properties of the device can be controlled via controlling the Fermi level of graphene thus its density of states available for intra-band transitions [8][9][10][11]. Although graphene metamaterials have been widely employed in devices modulating the amplitude of a transmitted terahertz beam (e.g., [12][13][14]), graphene-based structures controlling phase have not yet been proposed in the literature.…”

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].…”