Polarization Characteristics of Alumina Films Anodized at Low Temperature

Abstract
A prominent polarization function appears in anodic alumina films when oxidation is carried out at low temperature around 0°C. The alumina film that is anodized at 25 V and 0°C exhibits the extinction ratio of >30 dB/mm at the wavelengths of 0.6-1.6 µm. The polarization function seems to originate from unoxidized aluminum, which increases upon lowering of the anodization temperature. Using the polarization function, we fabricated a polarizer consisting of laminated alumina films.