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Structural asymmetry and induced optical magnetism in plasmonic nanosandwiches

Tavakol Pakizeh (Institutionen för teknisk fysik, Bionanofotonik) ; Alexandre Dmitriev (Institutionen för teknisk fysik, Bionanofotonik) ; M.S. Abrishamian ; N. Granpayeh ; Mikael Käll (Institutionen för teknisk fysik, Bionanofotonik)
J. Opt. Soc. Am. B Vol. 25 (2008), p. 659.
[Artikel, refereegranskad vetenskaplig]

A number of recent studies have shown that hybridized antiphase dipolar plasmons, qualitatively similar to magnetic 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 separated by a thin SiO2 layer, affects their near- and far-field optical properties using point-dipole analysis, electrodynamics simulations, and optical spectroscopy. We find that the strength of the antiphase resonant mode can be increased significantly compared to a symmetrical sandwich if the diameters or thicknesses of the nanodisks in the sandwich are made to differ. Such asymmetrical nanosandwiches also exhibit a generally stronger magnetic response, 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 enhancement depends on which side of the sandwich that is first illuminated.



Denna post skapades 2008-12-22. Senast ändrad 2017-10-03.
CPL Pubid: 82586

 

Institutioner (Chalmers)

Institutionen för teknisk fysik, Bionanofotonik (2007-2015)

Ämnesområden

Optik

Chalmers infrastruktur