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Achieving 100% amplitude modulation depth in the terahertz range with graphene-based tuneable capacitance metamaterials

Ruqiao Xia Orcid Logo, Nikita W. Almond, Wadood Tadbier, Stephen J. Kindness, Riccardo Degl’Innocenti Orcid Logo, Yuezhen Lu, Abbie Lowe, Ben Ramsay, Lukas A. Jakob, James Dann, Stephan Hofmann, Harvey E. Beere, Sergey A. Mikhailov, David Ritchie Orcid Logo, Wladislaw Michailow Orcid Logo

Light: Science & Applications, Volume: 14, Start page: 256

Swansea University Author: David Ritchie Orcid Logo

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DOI (Published version): 10.1038/s41377-025-01945-4

Abstract

Effective control of terahertz radiation requires fast and efficient modulators with a large modulation depth—a challenge that is often tackled by using metamaterials. Metamaterial-based active modulators can be created by placing graphene as a tuneable element shunting regions of high electric fiel...

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Published in: Light: Science & Applications
ISSN: 2047-7538
Published: Springer Nature 2025
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URI: https://cronfa.swan.ac.uk/Record/cronfa70119
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spelling 2025-08-06T10:08:35.2628027 v2 70119 2025-08-06 Achieving 100% amplitude modulation depth in the terahertz range with graphene-based tuneable capacitance metamaterials e943ea127ff7b7771c2b27c15b96c6fa 0000-0002-9844-8350 David Ritchie David Ritchie true false 2025-08-06 BGPS Effective control of terahertz radiation requires fast and efficient modulators with a large modulation depth—a challenge that is often tackled by using metamaterials. Metamaterial-based active modulators can be created by placing graphene as a tuneable element shunting regions of high electric field confinement in metamaterials. However, in this common approach, the graphene is used as a variable resistor, and the modulation is achieved by resistive damping of the resonance. In combination with the finite conductivity of graphene due to its gapless nature, achieving 100% modulation depth using this approach remains challenging. Here, we embed nanoscale graphene capacitors within the gaps of the metamaterial resonators, and thus switch from a resistive damping to a capacitive tuning of the resonance. We further expand the optical modulation range by device excitation from its substrate side. As a result, we demonstrate terahertz modulators with over four orders of magnitude modulation depth (45.7 dB at 1.68 THz and 40.1 dB at 2.15 THz), and a reconfiguration speed of 30 MHz. These tuneable capacitance modulators are electrically controlled solid-state devices enabling unity modulation with graphene conductivities below 0.7 mS. The demonstrated approach can be applied to enhance modulation performance of any metamaterial-based modulator with a 2D electron gas. Our results open up new frontiers in the area of terahertz communications, real-time imaging, and wave-optical analogue computing. Journal Article Light: Science & Applications 14 256 Springer Nature 2047-7538 Metamaterials; Optical properties and devices; Photonic devices; Terahertz optics 4 8 2025 2025-08-04 10.1038/s41377-025-01945-4 COLLEGE NANME Biosciences Geography and Physics School COLLEGE CODE BGPS Swansea University Another institution paid the OA fee W.M. thanks Trinity College Cambridge for a Junior Research Fellowship. W.T. was supported by the UK Engineering and Physical Sciences Research Council (EPSRC) grant EP/S023046/1 for the EPSRC Centre for Doctoral Training in Sensor Technologies for a Healthy and Sustainable Future. The authors acknowledge EPSRC funding from the HyperTerahertz grant, no. EP/P021859/1, and the TeraCom grant, no. EP/W028921/1. 2025-08-06T10:08:35.2628027 2025-08-06T09:57:30.8043555 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Physics Ruqiao Xia 0009-0003-7608-057X 1 Nikita W. Almond 2 Wadood Tadbier 3 Stephen J. Kindness 4 Riccardo Degl’Innocenti 0000-0003-2655-1997 5 Yuezhen Lu 6 Abbie Lowe 7 Ben Ramsay 8 Lukas A. Jakob 9 James Dann 10 Stephan Hofmann 11 Harvey E. Beere 12 Sergey A. Mikhailov 13 David Ritchie 0000-0002-9844-8350 14 Wladislaw Michailow 0000-0002-2573-9448 15 70119__34916__1914b3dfd5c7449caefd018b6b76959d.pdf 41377_2025_Article_1945.pdf 2025-08-06T09:57:30.8037089 Output 1200569 application/pdf Version of Record true © The Author(s) 2025. This article is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0). true eng http://creativecommons.org/licenses/by/4.0/
title Achieving 100% amplitude modulation depth in the terahertz range with graphene-based tuneable capacitance metamaterials
spellingShingle Achieving 100% amplitude modulation depth in the terahertz range with graphene-based tuneable capacitance metamaterials
David Ritchie
title_short Achieving 100% amplitude modulation depth in the terahertz range with graphene-based tuneable capacitance metamaterials
title_full Achieving 100% amplitude modulation depth in the terahertz range with graphene-based tuneable capacitance metamaterials
title_fullStr Achieving 100% amplitude modulation depth in the terahertz range with graphene-based tuneable capacitance metamaterials
title_full_unstemmed Achieving 100% amplitude modulation depth in the terahertz range with graphene-based tuneable capacitance metamaterials
title_sort Achieving 100% amplitude modulation depth in the terahertz range with graphene-based tuneable capacitance metamaterials
author_id_str_mv e943ea127ff7b7771c2b27c15b96c6fa
author_id_fullname_str_mv e943ea127ff7b7771c2b27c15b96c6fa_***_David Ritchie
author David Ritchie
author2 Ruqiao Xia
Nikita W. Almond
Wadood Tadbier
Stephen J. Kindness
Riccardo Degl’Innocenti
Yuezhen Lu
Abbie Lowe
Ben Ramsay
Lukas A. Jakob
James Dann
Stephan Hofmann
Harvey E. Beere
Sergey A. Mikhailov
David Ritchie
Wladislaw Michailow
format Journal article
container_title Light: Science & Applications
container_volume 14
container_start_page 256
publishDate 2025
institution Swansea University
issn 2047-7538
doi_str_mv 10.1038/s41377-025-01945-4
publisher Springer Nature
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Physics{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Physics
document_store_str 1
active_str 0
description Effective control of terahertz radiation requires fast and efficient modulators with a large modulation depth—a challenge that is often tackled by using metamaterials. Metamaterial-based active modulators can be created by placing graphene as a tuneable element shunting regions of high electric field confinement in metamaterials. However, in this common approach, the graphene is used as a variable resistor, and the modulation is achieved by resistive damping of the resonance. In combination with the finite conductivity of graphene due to its gapless nature, achieving 100% modulation depth using this approach remains challenging. Here, we embed nanoscale graphene capacitors within the gaps of the metamaterial resonators, and thus switch from a resistive damping to a capacitive tuning of the resonance. We further expand the optical modulation range by device excitation from its substrate side. As a result, we demonstrate terahertz modulators with over four orders of magnitude modulation depth (45.7 dB at 1.68 THz and 40.1 dB at 2.15 THz), and a reconfiguration speed of 30 MHz. These tuneable capacitance modulators are electrically controlled solid-state devices enabling unity modulation with graphene conductivities below 0.7 mS. The demonstrated approach can be applied to enhance modulation performance of any metamaterial-based modulator with a 2D electron gas. Our results open up new frontiers in the area of terahertz communications, real-time imaging, and wave-optical analogue computing.
published_date 2025-08-04T05:30:01Z
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