Observation of surface states in a truncated photonic crystal slab

The effect of lattice termination on the surface states in a two-dimensional truncated photonic crystal slab is experimentally studied in a high-index-contrast silicon-on-insulator system. A single-mode silicon strip waveguide that is separated from the photonic crystal by a trench of variable width is used to evanescently couple to surface states in the surrounding lattice. It is demonstrated that the dispersion of the surface states depends strongly on the specific termination of the lattice.