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Perfect absorption in GaAs metasurfaces near the bandgap edge

Hale, LL; Vabischevich, PP; Siday, T; Harris, CT; Luk, TS; Addamane, SJ; Reno, JL; ... Mitrofanov, O; + view all (2020) Perfect absorption in GaAs metasurfaces near the bandgap edge. Optics Express , 28 (23) pp. 35284-35296. 10.1364/OE.404249. Green open access

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Abstract

Perfect optical absorption occurs in a metasurface that supports two degenerate and critically-coupled modes of opposite symmetry. The challenge in designing a perfectly absorbing metasurface for a desired wavelength and material stems from the fact that satisfying these conditions requires multi-dimensional optimization often with parameters affecting optical resonances in non-trivial ways. This problem comes to the fore in semiconductor metasurfaces operating near the bandgap wavelength, where intrinsic material absorption varies significantly. Here we devise and demonstrate a systematic process by which one can achieve perfect absorption in GaAs metasurfaces for a desired wavelength at different levels of intrinsic material absorption, eliminating the need for trial and error in the design process. Using this method, we show that perfect absorption can be achieved not only at wavelengths where GaAs exhibits high absorption, but also at wavelengths near the bandgap edge. In this region, absorption is enhanced by over one order of magnitude compared a layer of unstructured GaAs of the same thickness.

Type: Article
Title: Perfect absorption in GaAs metasurfaces near the bandgap edge
Location: United States
Open access status: An open access version is available from UCL Discovery
DOI: 10.1364/OE.404249
Publisher version: http://dx.doi.org/10.1364/OE.404249
Language: English
Additional information: Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
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/10115670
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