Surface-plasmon photonic band gaps in dielectric gratings on a flat metal surface

Photonic band gaps created by Bragg scattering of the surface plasmon polaritons are observed from dielectric grating structures on a flat metal surface. Observation results that directly image the band gaps are confirmed by the well-known numerical calculation method of diffraction, the rigorous coupled-wave analysis method. A numerical model based on the plane wave expansion method is also developed for estimation of the surface-plasmon band-gap characteristics in our dielectric-on-metal system. Consistency among the results of the band structures obtained from the experiment and the two numerical methods is achieved.