title: Plasmonic control of extraordinary optical transmission in the infrared regime.
abstract: We demonstrate that the spectral location of extraordinary optical transmission (EOT) resonances in metallic arrays of rectangular holes can be plasmonically tuned in the near and mid-infrared ranges. The experiments have been performed on patterned gold films. We focus on a subset of localized resonances occurring close to the cut-off wavelength of the holes, λc. Metals are usually regarded as perfect electric conductors in the infrared regime, with an EOT cut-off resonance found around λc= 2 L for rectangular holes (L being the long edge). For real metals, the penetration of the electromagnetic fields is simply seen as effectively enlarging L. However, by changing the hole short edge, we have found that λcvaries due to the excitation of gap surface plasmon polaritons. Finite-element calculations confirm that in these high aspect ratio rectangles with short edges two important aspects have to be taken into account in order to explain the experiments: the finite conductivity of the metal and the excitation of gap-surface plasmons inside the nanoholes.
authors.affiliation: Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza, E-50018 Zaragoza, Spain. Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009 Zaragoza, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Sangiao
authors.forename: F
authors.initials: F
authors.lastname: Freire
authors.forename: F
authors.initials: F
authors.lastname: de León-Pérez
authors.forename: S G
authors.initials: SG
authors.lastname: Rodrigo
authors.forename: J M
authors.initials: JM
authors.lastname: De Teresa