Coupling of evanescent s-polarized waves to the far field by waveguide modes in metallic arrays

MARCELO LESTER,; DIANA CARINA SKIGIN

JOURNAL OF OPTICS. A, PURE AND APPLIED OPTICS (PRINT)

Institute of Physics Publishing

Año: 2007 vol. 9 p. 81 - 87

1464-4258

In this paper we show that enhanced optical transmission through a 1Dperiodic slit array comprising real metallic cylinders is possible fors-polarization when the array is near a dielectric interface. We investigate thebehaviour of this structure under s-polarized illumination, in which casesurface plasmons are not excited. Numerical results show that the transmittedintensity appears as a periodic function of the slit depth, for propagating aswell as for evanescent incidence, suggesting that this behaviour is related tothe excitation of waveguide modes in the slits. In particular, the coupling ofevanescent to propagating electromagnetic waves is investigated. It is shownthat s-polarized evanescent waves generated at the interface can betransformed into propagating waves if the optical width of the slits allowspropagation of the first waveguide mode. As the interface approaches thearray, the transmitted intensity increases for evanescent incidence.