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Terahertz Detection Using Enhanced Two-Step Absorption in Photoconductive Metasurfaces Gated at lambda=1.55 mu m

Jung, Hyunseung; Hale, Lucy L; Briscoe, Jayson; Sarma, Raktim; Luk, Ting Shan; Addamane, Sadhvikas J; Reno, John L; ... Mitrofanov, Oleg; + view all (2022) Terahertz Detection Using Enhanced Two-Step Absorption in Photoconductive Metasurfaces Gated at lambda=1.55 mu m. Advanced Optical Materials , Article 2201838. 10.1002/adom.202201838.

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Abstract

Superior ultrafast photoconductive properties make low temperature grown (LT) GaAs one of the best materials for photoconductive terahertz (THz) detection. However, the large bandgap of LT-GaAs limits its operation to gating at wavelengths shorter than 870 nm. Here, it is demonstrated for the first time that nanostructuring the LT-GaAs into a highly absorbing metasurface enables THz photoconductive detection with a pulsed laser at λ = 1.55 µm. The very weak sub-bandgap absorption mediated by midgap states in LT-GaAs is strongly enhanced using the concept of perfect absorption via degenerate critical coupling. Integrated with a THz antenna, the LT-GaAs metasurface enables high sensitivity THz detection with a high dynamic range of 60 dB and large bandwidth up to 4.5 THz. The LT-GaAs metasurface has the potential to serve as a universal ultrafast switching element for THz applications, enabling low-cost, turn-key THz systems for a variety of real-world applications.

Type: Article
Title: Terahertz Detection Using Enhanced Two-Step Absorption in Photoconductive Metasurfaces Gated at lambda=1.55 mu m
DOI: 10.1002/adom.202201838
Publisher version: https://doi.org/10.1002/adom.202201838
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: ANTENNAS, GENERATION, Materials Science, Materials Science, Multidisciplinary, metasurfaces, nanofabrication, Optics, photoconductive antenna, Physical Sciences, POWER, RADIATION, Science & Technology, spectroscopy, Technology, terahertz detection, THZ
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Electronic and Electrical Eng
URI: https://discovery.ucl.ac.uk/id/eprint/10160554
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