Open AccessPerfect absorption in GaAs metasurfaces near the bandgap edge
Author(s) -
Lucy L. Hale,
P. P. Vabischevich,
Thomas Siday,
Charles Thomas Harris,
Ting S. Luk,
Sadhvikas Addamane,
John L. Reno,
Igal Brener,
Oleg Mitrofanov
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.404249
Subject(s) - absorption (acoustics) , wavelength , optics , materials science , band gap , optoelectronics , degenerate energy levels , absorption edge , semiconductor , physics , quantum mechanics
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.