Abstract
Recently, plasmon-induced optical magnetism has attracted much research interest in nanophotonics and plasmonics due to intriguing applications in optical metamaterials, and ultrasensitive plasmonic nano-metrology, among many others. Here, a strong in-plane magnetic dipolar resonance in an ultrathin plasmonic nanocavity consisting of a silica-coated gold nanosphere dimer coupled to a gold thin film is observed experimentally and explained theoretically. Multipolar expansion and numerical simulation disclose that such magnetic resonance is induced by a displacement current loop circulating around a nanometer thick triangular region in the cavity. The spectral response and radiation polarization of the magnetic mode are “visualized” by using a polarization-resolved dark-field imaging system at the single-particle level. The resonance responses of this magnetic mode highly depends on cavity gap thickness, nanosphere dimension, and the incident angle, allowing straightforward resonance tuning from the visible to near-infrared region and thus opening up a new avenue for magnetic resonance-enhanced nonlinear optics and chiral optics.
Original language | English |
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Article number | 2000068 |
Journal | Laser and Photonics Reviews |
Volume | 14 |
Issue number | 9 |
DOIs | |
Publication status | Published - 1 Sept 2020 |
Keywords
- dimer-on-film
- magnetic resonance
- multipolar expansion
- optical magnetism
- plasmonic nanocavity
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics