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Terahertz Pulse Generation from GaAs Metasurfaces

Hale, Lucy L; Jung, Hyunseung; Gennaro, Sylvain D; Briscoe, Jayson; Harris, C Thomas; Luk, Ting Shan; Addamane, Sadhvikas J; ... Mitrofanov, Oleg; + view all (2022) Terahertz Pulse Generation from GaAs Metasurfaces. ACS Photonics , 9 (4) pp. 1136-1142. 10.1021/acsphotonics.1c01908. Green open access

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Ultrafast optical excitation of select materials gives rise to the generation of broadband terahertz (THz) pulses. This effect has enabled the field of THz time-domain spectroscopy and led to the discovery of many physical mechanisms behind THz generation. However, only a few materials possess the required properties to generate THz radiation efficiently. Optical metasurfaces can relax stringent material requirements by shifting the focus onto the engineering of local electromagnetic fields to boost THz generation. Here we demonstrate the generation of THz pulses in a 160 nm thick nanostructured GaAs metasurface. Despite the drastically reduced volume, the metasurface emits THz radiation with efficiency comparable to that of a thick GaAs crystal. We reveal that along with classical second-order volume nonlinearity, an additional mechanism contributes strongly to THz generation in the metasurface, which we attribute to surface nonlinearity. Our results lay the foundation for engineering of semiconductor metasurfaces for efficient and versatile THz radiation emitters.

Type: Article
Title: Terahertz Pulse Generation from GaAs Metasurfaces
Location: United States
Open access status: An open access version is available from UCL Discovery
DOI: 10.1021/acsphotonics.1c01908
Publisher version: https://doi.org/10.1021/acsphotonics.1c01908
Language: English
Additional information: Copyright © 2022 American Chemical Society This is an open access article under the CC BY 4.0 license Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/)
Keywords: terahertz generation, surface nonlinearity, metasurface, shift current, optical rectification
UCL classification: 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
UCL > Provost and Vice Provost Offices > UCL BEAMS
URI: https://discovery.ucl.ac.uk/id/eprint/10149332
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