title: Lateral magnetic near-field imaging of plasmonic nanoantennas with increasing complexity.
abstract: The design of many promising, newly emerging classes of photonic metamaterials and subwavelength confinement structures requires detailed knowledge and understanding of the electromagnetic near-field interactions between their building blocks. While the electric field distributions and, respectively, the electric interactions of different nanostructures can be routinely measured, for example, by scattering near-field microscopy, only recently experimental methods for imaging the magnetic field distributions became available. In this paper, we provide direct experimental maps of the lateral magnetic near-field distributions of variously shaped plasmonic nanoantennas by using hollow-pyramid aperture scanning near-field optical microscopy (SNOM). We study both simple plasmonic nanoresonators, such as bars, disks, rings and more complex antennas. For the studied structures, the magnetic near-field distributions of the complex resonators have been found to be a superposition of the magnetic near-fields of the individual constituting elements. These experimental results, explained and validated by numerical simulations, open new possibilities for engineering and characterization of complex plasmonic antennas with increased functionality.
authors.affiliation: INPAC-Institute for Nanoscale Physics and Chemistry, KU Leuven, Celestijnenlaan 200 D, B-3001, Leuven, Belgium.
authors.forename: Denitza
authors.initials: D
authors.lastname: Denkova
authors.forename: Niels
authors.initials: N
authors.lastname: Verellen
authors.forename: Alejandro V
authors.initials: AV
authors.lastname: Silhanek
authors.forename: Pol
authors.initials: P
authors.lastname: Van Dorpe
authors.forename: Victor V
authors.initials: VV
authors.lastname: Moshchalkov
keywords: field superposition; nanoantenna interactions; near-field imaging; optical magnetic field; surface plasmon resonance