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- Pakizeh, Tavakol, 1977, et al.
(författare)
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Structural asymmetry and induced optical magnetism in plasmonic nanosandwiches
- 2008
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Ingår i: J. Opt. Soc. Am. B. ; 25, s. 659-
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Tidskriftsartikel (refereegranskat)abstract
- A number of recent studies have shown that hybridized antiphase dipolar plasmons, qualitatively similar tomagnetic dipole resonances, can be excited in metal–dielectric–metal structures over a wide frequency range.Here, we study how structural asymmetry in plasmonic nanosandwiches, composed of two Au disks separatedby a thin SiO2 layer, affects their near- and far-field optical properties using point-dipole analysis, electrodynamicssimulations, and optical spectroscopy. We find that the strength of the antiphase resonant mode can beincreased significantly compared to a symmetrical sandwich if the diameters or thicknesses of the nanodisks inthe sandwich are made to differ. Such asymmetrical nanosandwiches also exhibit a generally stronger magneticresponse, as characterized by the magnetic near-field enhancement in the region between the disks. However,symmetry breaking also leads to pronounced directionality effects in the magnetic near-field, i.e., the enhancementdepends on which side of the sandwich that is first illuminated.
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