Surface waves with near-zero or negative group velocity on one-dimensional photonic crystal coated with one metal film

We employ the Bloch theorem of periodic structures and transfer matrix method to study the surface modes of a semi-infinite one-dimensional photonic crystal coated with a metal film. There are two mechanisms guiding the surface modes: the surface plasmon resonances and the surface modes of periodic structure. The surface modes can occur in all lower gaps and result from different mechanisms in different gaps. Extremely slow group velocities and even negative group velocities have been found to these surface modes.