Open AccessPolarization-induced tunability of localized surface plasmon resonances in arrays of sub-wavelength cruciform apertures
Author(s) -
Paul G. Thompson,
Claudiu G. Biris,
Edward J. Osley,
Ophir Gaathon,
Richard M. Osgood,
Nicolae C. Panoiu,
Paul A. Warburton
Publication year - 2011
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.19.025035
Subject(s) - optics , plasmon , polarization (electrochemistry) , surface plasmon , materials science , wavelength , surface plasmon polariton , ray , extraordinary optical transmission , localized surface plasmon , cruciform , anisotropy , physics , chemistry , composite material
We demonstrate experimentally that by engineering the structural asymmetry of the primary unit cell of a symmetrically nanopatterned metallic film the optical transmission becomes strongly dependent on the polarization of the incident wave. By considering a specific plasmonic structure consisting of square arrays of nanoscale asymmetric cruciform apertures we show that the enhanced optical anisotropy is induced by the excitation inside the apertures of localized surface plasmon resonances. The measured transmission spectra of these plasmonic arrays show a transmission maximum whose spectral location can be tuned by almost 50% by simply varying the in-plane polarization of the incident photons. Comprehensive numerical simulations further prove that the maximum of the transmission spectra corresponds to polarization-dependent surface plasmon resonances tightly confined in the two arms of the cruciform aperture. Despite this, there are isosbestic points where the transmission, reflection, and absorption spectra are polarization-independent, regardless of the degree of asymmetry of the apertures.