Determination of the refractive indices of photonic crystal layers from anodic alumina

Samples of photonic crystals with a different number of structure periods were fabricated by the method of anodizing aluminum foil. Using the angular dependence of transmission spectra, transmission electron microscopy data and numerical simulation, the refractive indices of photonic crystal layers are determined. The structure of the samples, the thickness of the layers and their porosity were determined. The theory of the effective medium in the approximations of Bruggemann, Maxwell Garnett, Monecke, Landau–Lifshitz/Looyenga, Lorentz–Lorentz, del Rio–Zimmerman–Dawe, as well as the complex refractive index is applied to determine the refractive indices of the layers. All approximations showed similar values, which indicates the possibility of using them to describe heterogeneous dielectric media.