Structural asymmetry and induced optical magnetism in plasmonic nanosandwiches
Artikel i vetenskaplig tidskrift, 2008

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.

Författare

Tavakol Pakizeh

Chalmers, Teknisk fysik, Bionanofotonik

Alexander Dmitriev

Chalmers, Teknisk fysik, Bionanofotonik

M.S. Abrishamian

N. Granpayeh

Mikael Käll

Chalmers, Teknisk fysik, Bionanofotonik

J. Opt. Soc. Am. B

Vol. 25 659-

Ämneskategorier

Atom- och molekylfysik och optik