Optical spectroscopy of high dielectric contrast 3D photonic crystals

– Spectroscopy was performed along three distinct crystallographic axes of a high refractive index contrast photonic crystal and the spectra were compared with theoretical calculations. Deep dips were observed in the experimental spectra at 2.1 and 3.2μm and predicted by calculations. The photonic crystal was prepared through melt-imbibing of selenium into a self-assembled face-centered-cubic colloidal crystal template. As optical communications and computing technologies continue to gain in importance, there is an increasing need for devices that can control the flow of photons. Dielectric structures with large index of refraction contrast have the promise to lead to dramatic changes in photonic integration, which is one of the goals of microphotonics. Many designs for new devices have been proposed that incorporate photonic band gap (PBG) materials [1,2]. Possible applications for PBG structures include low-loss waveguides [3,4], low-threshold lasers [5], optical switching elements [6], and increased control of photochemical reactions. In analogy to semiconductors, which possess an electronic band gap, periodic dielectric structures can possess a photonic band gap (PBG) that prohibits the propagation of photons of a particular energy in any direction. PBG materials are a specific class of structures containing a periodic variation in refractive index in two or three dimensions. While PBG structures have been demonstrated convincingly in the radio frequency region, with wavelengths of millimeters to centimeters, few three-dimensional examples have been constructed with gaps in the visible or infrared (λ < 5μm), because of the difficulty in assembling three-dimensional micron scale structures. Processes such as lithography, laser-induced chemical vapor deposition and two-photon photopolymerization have been suggested as routes to three-dimensional structures [7–10], but their stepwise nature restricts them to the production of small devices and lower dimensionalities. The required refractive index contrast for the creation of a three-dimensional PBG is also a serious limitation. In the near-IR and visible region, there are a limited number of