PHOTONIC CRYSTALS

In this paper, we review the early motivation for photonic crystal res earch which was derived from the need for a photonic bandgap in quantu m optics. This led to a series of experimental and theoretical searche s for the elusive photonic bandgap structures: those three-dimensional ly periodic dielectric structures which are to photon waves, as semico nductor crystals are to electron waves. We shall describe how the phot onic semiconductor can be 'doped', producing tiny electromagnetic cavi ties. Finally, we shall summarize some of the anticipated implications of photonic band structure for quantum electronics and the prospects for the creation of photonic crystals in the optical domain.