Observation of surface photons on periodic dielectric arrays

The first observation to the authors' knowledge of electromagnetic surface waves in a two-dimensional dielectric crystal is reported. By using the coherent microwave transient spectroscopy technique, surface waves are shown to exist at frequencies within the photonic band gap for certain lattice terminations. Energy at gigahertz frequencies is coupled into the surface mode using a prism coupling technique. The experimental results are in excellent agreement with theoretical predictions.