Photonic band structures for surface waves on structured metal surfaces.

Photonic band structures of surface modes on structured metal surfaces with periodic holes in them are obtained using the full-vectorial finite-difference time-domain method. Surface modes do exist for almost all investigated lattice types with any hole size, shape and depth. The results for a square lattice of wax-filled box holes in brass are also in very good agreement with the experimental results. We also show that, for structured surfaces with holes of finite depth, the holes might act as cavities. Thus there exist propagating coupled cavity modes with low group velocity, confined at the surface and decaying exponentially into the dielectric above.