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arXiv · 2312.16330

Achieving 100% amplitude modulation depth in a graphene-based tuneable capacitance metamaterial

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

Effective control of terahertz radiation requires the development of efficient and fast modulators with a large modulation depth. This challenge is often tackled by using metamaterials, artificial sub-wavelength optical structures engineered to resonate at the desired terahertz frequency. Metamaterial-based devices exploiting graphene as the active tuneable element have been proven to be a highly effective solution for THz modulation. However, whilst the graphene conductivity can be tuned over a wide range, it cannot be reduced to zero due to the gapless nature of graphene, which directly limits the maximum achievable modulation depth for single-layer metamaterial modulators. Here, we demonstrate two novel solutions to circumvent this restriction: Firstly, we excite the modulator from the back of the substrate, and secondly, we incorporate air gaps into the graphene patches. This results in a ground-breaking graphene-metal metamaterial terahertz modulator, operating at 2.0-2.5 THz, which demonstrates a 99.01 % amplitude and a 99.99 % intensity modulation depth at 2.15 THz, with a reconfiguration speed in excess of 3 MHz. Our results open up new frontiers in the area of terahertz technology.

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Ruqiao Xia, Nikita W. Almond, Stephen J. Kindness, Sergey A. Mikhailov, Wadood Tadbier, Riccardo Degl'Innocenti, Yuezhen Lu, Abbie Lowe, Ben Ramsay, Lukas A. Jakob, James Dann, Stephan Hofmann, Harvey E. Beere, David A. Ritchie, Wladislaw Michailow. 2023-12-26. Achieving 100% amplitude modulation depth in a graphene-based tuneable capacitance metamaterial. https://arxiv.org/abs/2312.16330

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