Figure 4.

Reconfigurable plasmonic resonant metasurface. (a) Conceptual view of the plasmonic structure and tuning based on oxidation and photoreduction of Au UTMFs. (b) SEM image of the nanodisks patterned from a 4 nm Au UTMF. (c) Visible (VIS) and near IR (NIR) transmittance optical spectra of nanodisks as-fabricated (black), after O₂ plasma oxidation (red) and after UV photoreduction process (blue). The as-fabricated spectrum is shown in real scale; meanwhile, a 25%, 50%, 75%, and 100% offset in transmittance has been added to the first, second, third, and fourth oxidation and photoreduction cycles, respectively. (d, e) Transmittance and wavelength values at the minimum of the resonance depth of the nanodisks UTMF metasurface as-fabricated (black), after O₂ plasma oxidation (red), and after the UV photoreduction process (blue).