Suppressing Material Loss for Functional Nanophotonics Using Bandgap Engineering
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.
Cite
@article{arxiv.1912.04835,
title = {Suppressing Material Loss for Functional Nanophotonics Using Bandgap Engineering},
author = {Mingsong Wang and Alex Krasnok and Sergey Lepeshov and Guangwei Hu and Taizhi Jiang and Jie Fang and Brian A. Korgel and Andrea Alù and Yuebing Zheng},
journal= {arXiv preprint arXiv:1912.04835},
year = {2019}
}