Effect of grating period on the excitation of multiple surface- plasmon-polariton waves guided by the interface of a metal grating and a photonic crystal

The excitation of multiple surface-plasmon-polariton (SPP) waves guided by the interface of a metal and a onedimensional photonic crystal in the grating-coupled configuration was studied both experimentally and theoretically. Only p-polarized incident light was considered in the visible and near-infrared regimes. When the absorptance was plotted against the angle of incidence, the excitation of an SPP wave was indicated by an absorptance peak whose angular location did not change with the number of periods (beyond a threshold) of the photonic crystal. A decrease in the period of the metal grating resulted in shifting the excitation of the SPP waves to smaller wavelengths.