Effect of stacking faults on the optical properties of inverted opals

Stacking faults appear to be the most common type of defect in inverted opa ls which are good candidates for photonic crystals with absolute gaps in th e visible range of light. In this Letter we present for the first time a sy stematic study of the effect of stacking faults on the optical properties o f self-assembled photonic crystals, by means of large-scale transmittance c alculations for macroscopic slabs of inverted opals with randomly distribut ed stacking faults. We show that frequency gaps, as seen in optical transmi ssion experiments, will in general appear wider in the presence of stacking faults. We attribute the above to Anderson localization of light due to di sorder.