LAUSR

Abstract Ordered nanoporous anodic alumina (NAA) samples are fabricated by the two-step anodization process. The surface of NAA is modified by means of the spray pyrolysis of titanium dioxide (TiO2). The morphology and optical properties of the samples are investigated. UV–Vis-NIR reflectance of NAA and NAA coated with TiO2 has been both measured and simulated. The influence of pore diameter and thickness of both NAA and TiO2 in reflectance is analyzed. Pore diameters between 30 nm and 80 nm and thicknesses from 3 to 14 μm are evaluated for the NAA. TiO2 coating thicknesses from 87 nm to 438 nm are determined by the number of sprayed TiO2 layers. Samples up to 40 nm TiO2 coating exhibit an increase in the intensity of the oscillations produced by NAA. Whereas, thicker TiO2 coatings generate a modulated oscillating behavior in the UV–Vis-NIR region. Numerical simulation based on the Transfer Matrix Method has also been carried out to analyze the measured reflectance spectra. The porosity of films has been modeled using an effective medium approximation. It is found the importance of including some absorption in the UV–Vis zone of the NAA layers to obtain accurate predictions of the optical behavior of NAA.