STANDING-WAVE SURFACE-PLASMON RESONANCES WITH OVERHANGING ZERO-ORDER METAL GRATINGS

We have found that a relatively unknown and little understood type of standing-wave surface-plasmon resonance may be excited in strongly bla zed overhanging zero-order metallic gratings. A modeling code based on an oblique coordinate transformation has been implemented to evaluate the optical response of these structures. For certain dimensions of s urface topography, very strong resonant absorption of light is found t hat is insensitive to the angle of incidence yet is sharply wavelength selective. These resonances are not the well-known geometrical cavity resonances but have smaller periodicities determined by the self-coup ling of surface-plasmon modes on the overhanging surfaces. (C) 1998 Op tical Society of America. [S0740-3232(98)01111-9]. OCIS codes: 050.005 0, 240.0240, 050.1940, 050.1970, 050.2770, 240.6680.