Controlling phase of microwaves with active graphene surfaces

Date
2017
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Source Title
Applied Physics Letters
Print ISSN
0003-6951
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American Institute of Physics Inc.
Volume
110
Issue
16
Pages
Language
English
Type
Article
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Abstract

In this letter, we report a method to control the reflection phase of microwaves using electrically tunable graphene devices. The device consists of mutually gated large-area graphene layers placed at a quarter-wave distance from a metallic surface. This device structure yields electrically tunable resonance absorbance and step-like phase shift around the resonance frequency when the impedance of graphene matches with the free space impedance. Electrostatic control of charge density on graphene yields unprecedented ability to control both intensity (>50 dB) and phase (∼π) of the reflected electromagnetic waves with voltage. Furthermore, using the asymmetry of the doping at opposite polarity of the bias voltages, we showed bidirectional phase control with the applied voltage.

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Published Version (Please cite this version)