We have experimentally observed the eigenmode splitting due to coupling of the evanescent defect modes in three-dimensional photonic crystals. The splitting was well explained with a theory based on the classical wave analog of the tight-binding (TB) formalism in solid state physics. The experimental results were used to extract the TB parameters. A new type of waveguiding in a photonic crystal was demonstrated experimentally. A complete transmission was achieved throughout the entire waveguiding band. We have also obtained the dispersion relation for the waveguiding band of the coupled periodic defects from the transmission-phase measurements and from the TB calculations.

We report the design and fabrication of a multilayered macroscopic fiber preform and the subsequent drawing and optical characterization of extended lengths of omnidirectional dielectric mirror fibers with submicrometer layer thickness. A pair of glassy materials with substantially different indices of refraction, but with similar thermomechanical properties, was used to construct 21 layers of alternating refractive index surrounding a tough polymer core. Large directional photonic band gaps and high reflection efficiencies comparable to those of the best metallic reflectors were obtained. Potential applications of these fibers include woven fabrics for radiation barriers, spectral authentication of cloth, and filters for telecommunications.

We proposed and demonstrated two different methods to split electromagnetic waves in three-dimensional photonic crystals. By measuring transmission spectra, it was shown that the guided mode in a coupled-cavity waveguide can be splitted into the coupled-cavity or planar waveguide channels without radiation losses. The flow of electromagnetic waves through output waveguide ports can also be controlled by introducing extra defects into the crystals. Our results may have an important role in the design of efficient power splitters in a photonic circuit.

We investigate the radiation properties of an antenna that was formed by a hybrid combination of a monopole radiation source and a cavity built around a dielectric layer-by-layer three-dimensional photonic crystal. We measured a maximum directivity of 310, and a power enhancement of 180 at the resonant frequency of the cavity. We observed that the antenna has a narrow bandwidth determined by the cavity, where the resonant frequency can be tuned within the band gap of the photonic crystal. The measured radiation patterns agree well with our theoretical results.