Electrically tunable metasurface for dual-band spatial light modulation using the epsilon-near-zero effect

Posted on 21.09.2022 - 20:54
Electro-tunable metasurfaces have gained huge attention for active controlling of incident light at the nanoscale by engineering sub-wavelength meta-atoms. In this letter, for the first time, we propose a grating-assisted dual-band metasurface for spatial light modulation, that can operate in two crucial telecommunication wavelength bands, i.e., C-band and O-band. The proposed device consists of a silicon-nitride nanograting on top of a silicon–indium-tin-oxide (ITO)–alumina–gold stack. Effective medium theory combined with a modal analysis is used to study the guided-mode resonance dips at 1.55 μm and 1.31 μm in the reflectance spectra. We leverage epsilon-near-zero effect of ITO by applying external bias-voltage to introduce large modal loss, which leads to disappearance of the resonance dips at those wavelengths. We obtain high modulation depth of ~22.3 dB at 1.55 μm and ~19.5 dB at 1.31 μm with applied bias of –4 V and –5 V, respectively. The proposed metasurface, thus, could help realizing dual-band active nanophotonic devices.

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BHOWMIK, TANMAY; Sikdar, Debabrata (2022): Electrically tunable metasurface for dual-band spatial light modulation using the epsilon-near-zero effect. Optica Publishing Group. Collection. https://doi.org/10.6084/m9.figshare.c.6173530.v2
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