POLARIZATION CONVERSION THROUGH THE EXCITATION OF SURFACE-PLASMONS ON A METALLIC GRATING

Surface plasmon-polaritons may be excited by photons at a metal-air boundary if a grating is used to provide the necessary extra momentum. Rotation of the grating so that the grooves are no longer perpendicular to the plane of incidence reduces the coupling efficiency while at the same time producing some s-polarised radiation in the reflected beam. When the grooves are at 45° to the plane of incidence maximum p-s conversion is obtained. Conversion efficiencies of up to 66% have been recorded for silver-coated gratings of appropriate depth. By scanning the angle of incidence and using a crossed polariser on the detector a strong resonance peak is observed. The application of this phenomenon to optical sensing is considered. © 1990 Taylor & Francis Group, LLC.