Electromagnetic surface waves: photonic crystal–photonic crystal interface

It is demonstrated the existence of electromagnetic surface modes at the interface of two different one-dimensional photonic crystals. Contrary to common behavior of modes present at the surfaces of truncated photonic crystals embedded in dielectric media, these modes can reside above and below the light line for vacuum within the overlapping of band gaps of both photonic crystals. This behavior implies that they can be excited and observed without prism or grating configurations even under normal incidence from vacuum if proper conditions are fulfilled.