Xin Huang, Fan Yang, Bing Gao, Qi Yang, Jiamin Wu, and Wei He
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| Independently tunable metamaterials absorber for amplitude and frequency with graphene and STO layer. (a) Top view of the unit cell. (b) Schematic representation and geometrical characters of the unit cell. (c) Schematic representation of the proposed absorber, which consist of a graphene sheet, two dielectric layers and one metallic background layer, with the terahertz wave along the z-axis. The geometrical parameters are given. |
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-18-25902
A tunable metamaterial absorber is proposed in the terahertz regime. The amplitude and center frequency of the absorber can be tuned independently. Owing to the effective combination of graphene and strontium titanate (STO) in one metamaterial structure, the tunable properties of the amplitude and center frequency are implemented. The amplitude can be tuned by adjusting the chemical potential of graphene sheet, and center frequency can get a shift through temperature changes in the STO material. In a full-wave numerical simulation, the amplitude of the absorber can be tuned from approximately 100% to 35% with a fixed center frequency when chemical potential varies from 0.7 eV to 0.0 eV. The center frequency of the absorber can shift from 0.43 THz to 0.3 THz when temperature changes from 400 K to 200 K. The complex surface impedance of the graphene and permittivity of STO material in this research range are thoroughly examined, and the independently tunable mechanism of the absorber is explored by elucidating the electric field distribution. The influence of the oblique incidence of electromagnetic wave to the absorber is studied. The absorber can be scalable to the infrared and visible frequencies and demonstrates promising application on tunable sensors, filters, and photovoltaic devices.
© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
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