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Summary form only given. Photonic band gap (PBG) materials are artificial, periodic, dielectrics that enable engineering of the most fundamental properties of electromagnetic waves. These include the laws of refraction, diffraction, and spontaneous emission of light. Unlike traditional semiconductors that rely on the propagation of electrons through an atomic lattice. PBG materials execute their novel functions through selective trapping or "localization of light". Three dimensional (3D) PBG materials offer a unique opportunity to simultaneously (i) synthesize micron-scale 3D optical circuits that do not suffer from diffractive losses and (ii) engineer the electromagnetic vacuum density of states in this 3D optical micro-chip. The 3D PBG enables broadband on-chip optical communication in fully three-dimensional optical micro-circuits. Unlike traditional wave-guides that confine light in a high refractive index core by total internal reflection, the circuit paths in a PBG material may consist of air. They guide light through wave interference effects, the hallmark of the localization phenomenon. In the case of the PBG optical circuit, there are three geometrical dimensions for device integration and an additional dimension of frequency bandwidth, whereby hundreds of optical wavelength channels of information can be conveyed in parallel through a single PBG wave-guide. I review recent approaches to micro-fabrication of photonic crystals with a large 3D PBG centered near 1.5 microns. These include direct laser-writing techniques, holographic lithography, silicon double inversion, and a newly invented optical phase mask lithography technique.