Photonic band structure: the path to three-dimensional microcavities

Analogous to electron waves in a crystal, light waves in a three-dimensionally periodic dielectric structure should be described by band theory. The concept of photonic band structure 1 is gaining rapid 2−5 acceptance. The concepts of reciprocal space, Brillouin zones, dispersion relations, Block wave functions, van Hove singularities, etc. are now being applied to optical waves.