Bound modes of two-dimensional photonic crystal waveguides

It is now widely recognised that a volume of dielectric material with an appropriately designed periodic microstructure — a photonic crystal — will support a full three-dimensional photonic band gap (PBG) [1]. Over the frequency range spanned by the PBG, all electromagnetic modes are suppressed within the volume, allowing a single resonance (or photonic state) to be introduced by means of a structural point defect [2]. This unique ability to tamper strongly with the electromagnetic mode density enables the channelling of spontaneous emission into one or a few electromagnetic modes, and is attractive for enhancing the emission rate from light emitting diodes, and in achieving low threshold highly efficient operation in micro-cavity lasers [3].