Fig. 7

Color map of the reflectance calculated using the RCWA method for a grating period p of 350 nm, duty ratio w/p of 0.75, an 80-nm-thick Ag layer, and a wavelength λ of 450 nm as a function of wavenumber and energy. The color bar shows the magnitude of the reflectance. The yellow dashed lines present the dispersion relationship of the Rayleigh anomaly [Eq. (1)] in the double-layer wire-grid structure for n = 1.00 and 1.54. The white dot is the position of the reflectance dip which is the intersection of the black solid line (2.76 eV) and the map locus for n = 1