title: Polarization-induced tunability of localized surface plasmon resonances in arrays of sub-wavelength cruciform apertures.
abstract: 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.
authors.affiliation: 1London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Thompson
authors.forename: Claudiu G
authors.initials: CG
authors.lastname: Biris
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Osley
authors.forename: Ophir
authors.initials: O
authors.lastname: Gaathon
authors.forename: Richard M
authors.initials: RM
authors.lastname: Osgood
authors.forename: Nicolae C
authors.initials: NC
authors.lastname: Panoiu
authors.forename: Paul A
authors.initials: PA
authors.lastname: Warburton
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D008962:Models, Theoretical; D055096:Optical Devices; D012031:Refractometry / Q000295:instrumentation*; D012542:Scattering, Radiation; D020349:Surface Plasmon Resonance / Q000295:instrumentation*