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arXiv · 1912.04835

Suppressing Material Loss for Functional Nanophotonics Using Bandgap Engineering

Mingsong Wang·Alex Krasnok·Sergey Lepeshov·Guangwei Hu·Taizhi Jiang·Jie Fang·Brian A. Korgel·Andrea Alù·Yuebing Zheng
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Abstract

All-dielectric nanoantennas 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 a larger absorption coefficient of Si and other high-index semiconductors, thus encouraging the search for alternative dielectrics for nanophotonics. In this paper, 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 resonant modes in single a-Si:H NPs with Q factors up to ~100, in the visible and near-IR range for the first time. In order to demonstrate light-matter interaction enhancement, we realize highly tunable all-dielectric nanoantennas coupling them to photochromic spiropyran (SP) molecules. We show ~70% reversible all-optical tuning of light scattering at the high-Q resonant mode, along with minor tunability when out of resonance. This remarkable all-optical tuning effect is achieved under a low incident light intensity ~3.8 W/cm2 for UV light and ~1.1*10^2 W/cm2 for green light.

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Mingsong Wang, Alex Krasnok, Sergey Lepeshov, Guangwei Hu, Taizhi Jiang, Jie Fang, Brian A. Korgel, Andrea Alù, Yuebing Zheng. 2019-12-10. Suppressing Material Loss for Functional Nanophotonics Using Bandgap Engineering. https://arxiv.org/abs/1912.04835

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