REFLECTION GRATINGS AS POLARIZATION CONVERTERS

An experimental and theoretical modelling study of corrugated gold sur faces, where the refractive index of the upper medium is varied to cha nge the effective wavelength of the incident radiation, is presented. For certain corrugation amplitudes we show that it is possible to conv ert nearly 100% of plane polarized light incident normal to the averag e plane of the,orating surface into the orthogonal polarization. Inves tigations of the incident radiation's E-fields immediately above the c orrugated surface show that the physical origin of this phenomenon res ts with the phase retardation introduced by reflection. It is found th at optimum polarization conversion occurs when the component of the op tical E-field parallel to the grating wavevector is retarded by 180 de grees with respect to the component parallel to the grooves. (C) 1997 Elsevier Science B.V.