title: Narrow gaps for transmission through metallic structured gratings with subwavelength slits.
abstract: Transmission dips in the response of metallic compound gratings formed by several wires and slits in each period have been recently reported for normal illumination. These anomalies are generated by a particular arrangement of the magnetic field phases inside the subwavelength slits, and they are characterized by a significant enhancement of the interior field. We investigate the microwave response of such systems under non-normal illumination and show that new phase modes appear in this configuration. Contrary to the effect produced by a defect in a photonic crystal, these systems exhibit forbidden channels within a permitted band. We also found that the appearance of these resonances is not highly dependent on the slits' width and thickness, even though these parameters modify the overall transmittance.
authors.affiliation: Grupo de Electromagnetismo Aplicado, Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón I, C1428EHA Buenos Aires, Argentina. dcs@df.uba.ar
authors.forename: Diana C
authors.initials: DC
authors.lastname: Skigin
authors.forename: Ricardo A
authors.initials: RA
authors.lastname: Depine