Solid-state terahertz intensity modulator based on a single-layer graphene-metal metasurface

Ruqiao Xia; Nikita W. Almond; Harvey E. Beere; David A. Ritchie; Wladislaw Michailow

doi:10.1117/12.2679912

17 October 2023 Solid-state terahertz intensity modulator based on a single-layer graphene-metal metasurface

Ruqiao Xia, Nikita W. Almond, Harvey E. Beere, David A. Ritchie, Wladislaw Michailow

Proceedings Volume 12740, Emerging Imaging and Sensing Technologies for Security and Defence VIII; 127400G (2023) https://doi.org/10.1117/12.2679912
Event: SPIE Security + Defence, 2023, Amsterdam, Netherlands

Abstract

The realization of next-generation communication systems requires fast and efficient THz signal control, enabling a data stream to be encoded into a THz-frequency signal. This requires modulators with both a high modulation depth and reconfiguration speed; both are important figures of merit for communication devices. Metamaterial modulators using a brickwork antenna structure have recently shown promising performance below 1 THz. In our work, we designed, fabricated, and characterised a solid-state optical intensity modulator operating at 2.2 THz using a single-layer metasurface loaded with CVD-grown graphene. We employ an equivalent circuit model to optimize the geometric parameters for the 2 – 3 THz range, accessible by quantum cascade lasers. The incident electric field is confined by the metallic antenna arrays to the narrow resonator gaps, where patches of commercially grown graphene are defined. The graphene conductivity can be continuously tuned by applying a back-gate voltage between the p-doped silicon substrate and the metamaterial on top, separated by a 300 nm SiO2 dielectric layer. By gating the graphene, the transmitted electric field is modulated. The transmission of the device has been studied with terahertz time-domain spectroscopy. Our single-layer solid-state device achieves an intensity modulation depth greater than 68% at 2.2 THz.

Conference Presentation

(2023) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Ruqiao Xia, Nikita W. Almond, Harvey E. Beere, David A. Ritchie, and Wladislaw Michailow "Solid-state terahertz intensity modulator based on a single-layer graphene-metal metasurface", Proc. SPIE 12740, Emerging Imaging and Sensing Technologies for Security and Defence VIII, 127400G (17 October 2023); https://doi.org/10.1117/12.2679912

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