Photonic crystals are three-dimensional dielectric structures with lattice
parameter on the order of the wavelength of light. This has a similar
influece on the propagation of light as atomic crystals have on electrons.
Thus, the dispersion relation of light can be desribed with band structures
in a Brillouin zone in recipocal space. Photonic crystals are being pursued
to obtain a range of forbidden frequncies--a photonic bandgap - in the
optical range. This has important quantum optical consequ
