Suppressing material loss in the visible and near-infrared range for functional nanophotonics using bandgap engineering

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Date

2020-10-07

Authors

Wang, Mingsong
Krasnok, Alex
Lepeshov, Sergey
Hu, Guangwei
Jiang, Taizhi
Fang, Jie
Korgel, Brian A.
Alu, Andrea
Zhneg, Yuebing

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Publisher

Springer Nature Limited

Abstract

All-dielectric nanostructures have recently opened exciting opportunities for functional nanophotonics, owing to their strong optical resonances along with low material loss in the near-infrared range. Pushing these concepts to the visible range is hindered by their larger absorption coefficient, thus encouraging the search for alternative dielectrics for nanopho- tonics. Here, we employ bandgap engineering to synthesize hydrogenated amorphous Si nanoparticles (a-Si:H NPs) offering ideal features for functional nanophotonics. We observe significant material loss suppression in a-Si:H NPs in the visible range caused by hydrogenation-induced bandgap renormalization, producing strong higher-order resonant modes in single NPs with Q factors up to ~100 in the visible and near-IR range. We also realize highly tunable all-dielectric meta-atoms by coupling a-Si:H NPs to photochromic spiropyran molecules. ~70% reversible all-optical tuning of light scattering at the higher-order resonant mode under a low incident light intensity is demonstrated. Our results promote the development of high-efficiency visible nanophotonic devices.

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Wang, M., Krasnok, A., Lepeshov, S. et al. Suppressing material loss in the visible and near-infrared range for functional nanophotonics using bandgap engineering. Nat Commun 11, 5055 (2020). https://doi.org/10.1038/s41467-020-18793-y