Extraordinary transmission through a silver film perforated with bowtie-shaped aperture array in midinfrared region

Abstract

The transmission spectra of bowtie aperture consisting of opposing triangular holes arranged in rectangular array on silver/silicon structure were investigated. It is found that the second order surface plasmon polaritons mode is much stronger than the fundamental one. In addition, by increasing the separation and angles of the tips or silver film thickness, the second order modes decrease gradually. These phenomena suggest magnetic field coupling between metal tips which results in higher order mode enhancement. © 2011 American Institute of Physics.