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 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.
© 2008 Optical Society of AmericaFull Article | PDF Article
OSA Recommended Articles
T. Pakizeh, M. S. Abrishamian, N. Granpayeh, A. Dmitriev, and M. Käll
Opt. Express 14(18) 8240-8246 (2006)
Liu Qiu, Shuming Wang, Hui Liu, Tao Li, Shining Zhu, and Xiang Zhang
J. Opt. Soc. Am. B 28(7) 1655-1660 (2011)
J. Opt. Soc. Am. B 29(9) 2446-2452 (2012)