Enhanced terahertz focusing for a graphene-enabled active metalens.
Opt Express
; 28(23): 35179-35191, 2020 Nov 09.
Article
em En
| MEDLINE
| ID: mdl-33182969
ABSTRACT
Graphene-based terahertz (THz) metasurfaces have the advantages of ultra-small thickness, electrical tunability, and fast tuning speed. However, many such structures suffer low efficiency, especially for transmissive devices. Here we propose a hybrid structure for focusing THz waves with tunability and enhanced focusing efficiency, which is composed of a graphene-loaded metallic metasurface sandwiched by two mutually orthogonal gratings. Experimental results show that due to the multi-reflection between the metasurface layer and the grating layer, the focusing efficiency is enhanced by 1.8 times, and the focal length of the metalens is increased by 0.61â
mm when the applied gate voltage on the graphene is increased from 0â
V to 1.4â
V. We hope the proposed structure may open a new avenue for reconfigurable THz metasurfaces with high efficiencies.
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MEDLINE
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En
Ano de publicação:
2020
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Article