Thickness-dependent iridescence of one-dimensional photonic crystals based on anodic alumina

One-dimensional photonic crystals based on anodic alumina are of high practical importance in modern materials science and photonics owing to wide variety of their applications: from optoelectronics to decorative coatings. Although the variety of anodizing regimes allows one to design the periodic modulation of the porosity of oxide film, the information about the optimal number of layers needed for the appearance of intense photonic band gaps is absent. Here the variation in the spectral properties of one-dimensional photonic crystals on the thickness of porous anodic alumina is examined. The samples consisted of up to 300 periods are obtained by anodizing of aluminiumunder square-wave current profile in sulfuric acid electrolyte. Fabry-Perot optical interference of the porous film at different incident angles is used for the calculation of the wavelength dispersion of the effective refractive index of anodic alumina. The influence of the number of layers in anodic alumina photonic crystals on the intensity of photonic band gap and colour of oxide coating is discussed. (C) 2018 Elsevier Ltd. All rights reserved.