Anderson localization of light in inverted opals

We describe a photonic crystal disordered by stacking faults which can be realized in the laboratory and which exhibits an Anderson localization of light over certain regions of frequency. The localization length is obtained from a calculation of the transmittance of a slab of the material as a function of the thickness of the slab. The localization length depends on the frequency and the angle of incidence of the incident light. It appears that there are regions of frequency where all states of the electromagnetic field are either localized or delocalized, but we also find regions where localized states coexist with delocalized ones.