How Ultranarrow Gap Symmetries Control Plasmonic Nanocavity Modes: From Cubes to Spheres in the Nanoparticle-on-Mirror
de Nijs, Bart
American Chemical Society
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Chikkaraddy, R., Zheng, X., Benz, F., Brooks, L., de Nijs, B., Carnegie, C., Kleemann, M., et al. (2017). How Ultranarrow Gap Symmetries Control Plasmonic Nanocavity Modes: From Cubes to Spheres in the Nanoparticle-on-Mirror. ACS Photonics, 4 (3), 469-475. https://doi.org/10.1021/acsphotonics.6b00908
Plasmonic nanocavities with sub-5-nm gaps between nanoparticles support multiple resonances possessing ultra-high-field confinement and enhancements. Here we systematically compare the two fundamentally different resonant gap modes: transverse waveguide (s) and antenna modes (l), which, despite both tightly confining light within the gap, have completely different near-field and far-field radiation patterns. By varying the gap size, both experimentally and theoretically, we show how changing the nanoparticle shape from sphere to cube alters coupling of s and l modes, resulting in strongly hybridized (j) modes. Through rigorous group representation analysis we identify their composition and coupling. This systematic analysis of the Purcell factors shows that modes with optical field perpendicular to the gap are best to probe the optical properties of cavity-bound emitters, such as single molecules.
metasurfaces, nanocavities, patch antennas, plasmonics, Purcell factor, SERS, strong coupling
Is supplemented by: https://doi.org/10.17863/CAM.7777
We acknowledge financial support from EPSRC Grants EP/G060649/1, EP/K028510/1, and EP/L027151/1 and ERC Grant LINASS 320503. R.C. acknowledges support from the Dr. Manmohan Singh scholarship from St. John’s College. F.B. acknowledges support from the Winton Programme for the Physics of Sustainability. G.A.E.V., V.V.M., and X.Z. acknowledge the C2 project (C24/15/015) and the PDMK/14/126 project of KU Leuven, the FWO Long-Term Stay Abroad Project Grant V405115N, and the Methusalem Project funded by the Flemish government.
European Research Council (320503)
External DOI: https://doi.org/10.1021/acsphotonics.6b00908
This record's URL: https://www.repository.cam.ac.uk/handle/1810/264185