Waveguide coupling via magnetic gratings with effective strips

Published: April 14, 2018

Author(s)

Kevin Roccapriore, David Lyvers, Dean Brown, Ekaterina Poutrina, Augustine Urbas, Thomas A. Germer, Vladimir Drachev

Abstract

Gratings with complex multilayer strips are studied under inclined incident light. Great interest in these gratings is due to applications as input/output tools for waveguides and as subwavelength metafilms. The structured strips introduce anisotropy in the effective parameters, providing additional flexibility in polarization and angular dependences of optical responses. Their characterization is challenging in the intermediate regime between subwavelength and diffractive modes. The transition between modes occurs at the Wood’s anomaly wavelength, which is different at different angle of incidence. The usual characterization with an effective film using permittivity ϵ and permeability μ has limited effectiveness at normal incidence but does not apply at inclined illumination, due to the effect of periodicity. The optical properties are better characterized with effective medium strips instead of an effective medium layer to account for the multilayer strips and the underlying periodic nature of the grating. This approach is convenient for describing such intermediate gratings for two types of applications: both metafilms and the coupling of incident waves to waveguide modes or diffraction orders. The parameters of the effective strips are retrieved by matching the spectral-angular map at different incident angles.
Citation: Applied Sciences
Volume: 8
Issue: 4
Pub Type: Journals

Keywords

gratings, magnetic, metamaterials, waveguide
Created April 14, 2018, Updated February 05, 2019