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Achieving 100% amplitude modulation depth in the terahertz range with graphene-based tuneable capacitance metamaterials
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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
Light: Science & Applications, Volume: 14, Start page: 256
Swansea University Author:
David Ritchie
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© The Author(s) 2025. This article is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
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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...
| Published in: | Light: Science & Applications |
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| ISSN: | 2047-7538 |
| Published: |
Springer Nature
2025
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa70119 |
| 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 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. |
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| Keywords: |
Metamaterials; Optical properties and devices; Photonic devices; Terahertz optics |
| College: |
Faculty of Science and Engineering |
| Funders: |
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. |
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