Materials aspects of opals as photonic crystals

Opals have only a relatively recent history as photonic materials. The tortuous route from materials to devices might perhaps find compensation in the case and low cost of fabrication. Issues relating to the optical properties (such as crystalline quality, finite size effects and infiltration with other materials) are examined and developments leading to possible devices shown. We perform a study of the influence of finite size effects on the optical properties of the samples prior to comparison of experimental results and calculated energy bands, which may be determined along desired directions in reciprocal space. The role of intrinsic defects in the optical properties of the samples has been investigated. The optimization of the procedure to grow accurate amounts of amorphous silicon and germanium by CVD free of contamination in opals has been tackled. Multilayer systems of both semiconductors have been fabricated. Finally we present a method to fabricate opal based photonic crystals containing 2D cavities.