Jung, Hyunseung;
Hale, Lucy L;
Briscoe, Jayson;
Sarma, Raktim;
Luk, Ting Shan;
Addamane, Sadhvikas J;
Reno, John L;
... Mitrofanov, Oleg; + view all
(2023)
Terahertz Detection Using Enhanced Two-Step Absorption in Photoconductive Metasurfaces Gated at λ = 1.55 µm.
Advanced Optical Materials
, 11
(1)
, 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 λ = 1.55 µm |
| Open access status: | An open access version is available from UCL Discovery |
| 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: | metasurfaces, nanofabrication, photoconductive antenna, spectroscopy, terahertz detection |
| 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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