Experimental excitation of multiple surface-plasmon-polariton waves and waveguide modes in a one-dimensional photonic crystal atop a two-dimensional metal grating

The excitation of multiple surface-plasmon-polariton (SPP) waves and waveguide modes was experimentally demonstrated in a structure fabricated as a one-dimensional photonic crystal (PC) on top of a two-dimensional metal grating. The PC had two periods, each period comprising nine layers of silicon oxynitrides of different compositions. The individual excitations of the SPP waves and waveguide modes were also theoretically predicted using the Floquet theory, surface-multiplasmonics theory, and the transfer-matrix approach for multilayered waveguides. Both the theoretical and experimental results indicate broadband coupling of incident light of either linear polarization state to the guided waves of both types over a broad range of the angle of incidence.