Measurement of the photon dispersion relation in two-dimensional ordered dielectric arrays

We characterize the dispersion relation for electromagnetic-wave propagation in two-dimensional dielectric arrays, using the coherent microwave transient spectroscopy technique. Results of measurements along various symmetry directions of square and triangular lattices are presented. The experimental results are in excellent agreement with theoretical calculations made by using the plane-wave expansion technique. The theoretical calculations predict that transmission via certain modes is forbidden by symmetry, and our experimental results confirm this prediction. © 1993 Optical Society of America.