Fast and slow propagations of surface plasmon polaritons on metallic mesh gratings

Surface plasmon polariton (SPP) generations on silver-based metal-insulator-metal (MIM) cross mesh gratings were studied by polychromatic and monochromatic specular reflection. Centimeter area scale mesh grating samples were made using soft-lithography imprinting with a varied micro-sized array pitch. The mesh structures support multiple SPP orders with a periodicity-influenced mode generation. For the (+/- 1, 0) SPP modes steep dispersions thus high SPP group velocities V-g were obtained over an extended wavelength range of propagation. V-g were found to achieve a maximum at frequencies closer to the mesh periodicity.