Abstract- Graphene Terahertz Amplitude Modulation Enhanced by Square Ring Resonant Structure

 Liangping Xia,  Xin Zhang, Dongshan Wei. Hong-Liang Cui, Chunlei Du

http://ieeexplore.ieee.org/document/8141872/

A terahertz amplitude modulator based on graphene on a metallic square ring resonant structure is proposed. By separating the graphene and the metallic structure with a thin organic dielectric layer, both the resonant frequency and the amplitude of the transmission resonant peak are modulated when graphene is electrically tuned by a bias voltage. A maximal amplitude modulation depth of 72% at the frequency of 0.6 THz is achieved for the fabricated Terahertz modulator. An analysis model based on the transmission line theory is built to explore the modulation mechanism. Results of the transmission spectrum and the amplitude modulation indicate a good agreement between the transmission line theoretical predictions and the experimental measurements

Abstract-Amplitude Modulation of Anomalously Refracted Terahertz Waves with Gated-Graphene Metasurfaces

Teun-Teun Kim, Hyunjun Kim, Mitchell Kenney, Hyun Sung Park, Hyeon-Don Kim, Bumki Min, Shuang Zhang

http://onlinelibrary.wiley.com/doi/10.1002/adom.201700507/full

Although recent progress in metasurfaces has shown great promise for applications, optical properties in metasurfaces are typically fixed by their structural geometry and dimensions. Here, an electrically controllable amplitude of anomalously-refracted waves in a hybrid graphene/metasurface system are experimentally demonstrated, which consists of an artificially constructed two-dimensional metallic apertures array and naturally occurring two-dimensional carbon atoms (graphene) in the subwavelength-scale (< λ/10). Based on Pancharatnam–Berry phase and by careful design of a spatially linear phase profile, it is shown that the amplitude of anomalously refracted circularly cross-polarized terahertz waves can be effectively modulated by an applied gate voltage. The developed electrically tunable graphene metasurfaces may lead to various advanced applications that require dynamical control over electromagnetic waves, such as amplitude tunable active focusing lenses, vortex phase plates and dynamic holography.