Gittinger, M.; Höflich, K.; Smirnov, V.; Kollmann, H.; Lienau, C.; Silies, M.: Strongly coupled, high-quality plasmonic dimer antennas fabricated using a sketch-and-peel technique. Nanophotonics 9 (2020), p. 401–412
10.1515/nanoph-2019-0379
Open Access Version

Abstract:
A combination of helium- and gallium-ion beam milling together with a fast and reliable sketch-and-peel technique is used to fabricate gold nanorod dimer anten- nas with an excellent quality factor and with gap distances of less than 6 nm. The high fabrication quality of the sketch-and-peel technique compared to a conventional ion beam milling technique is proven by polarisation- resolved linear dark-field spectromicroscopy of isolated dimer antennas. We demonstrate a strong coupling of the two antenna arms for both fabrication techniques, with a quality factor of more than 14, close to the theoretical limit, for the sketch-and-peel–produced antennas com- pared to only 6 for the conventional fabrication process. The obtained results on the strong coupling of the plas- monic dimer antennas are supported by finite-difference time-domain simulations of the light-dimer antenna inter- action. The presented fabrication technique enables the rapid fabrication of large-scale plasmonic or dielectric nanostructures arrays and metasurfaces with single-digit nanometer scale milling accuracy.