Centrifugation and spin-coating method for fabrication of three-dimensional opal and inverse-opal structures as photonic crystal devices

We describe a simple and effective method, based on a combination of centrifugation and spin coating, developed for the fabrication by self-assembly of photonic crystal structures. The process produces compact 3-D arrays of polystyrene microspheres (opals) that are organized into crystalline lattices with single-crystal regions up to several hundred micrometers in size. These arrays are subsequently used as templates for infiltration with polyurethane. The resulting inverse opals are characterized by Fourier transform IR reflection spectroscopy and exhibit strong reflectivity for a band of wavelengths in excellent agreement with band structure calculations. This process offers the ability to rapidly form 3-D photonic crystals using inexpensive instrumentation, which makes it attractive for an array of applications. Process parameters, fabricated structures, and their experimental characterization are presented. (C) 2004 Society of Photo-Optical Instrumentation Engineers.