Influence of Anodization Mode and Temperature on the Optical Properties of Photonic Crystals Based on Porous Anodic Alumina

Abstract

Porous anodic alumina (PAA) with periodic structure was produced by sinusoidal pulse anodization (SPA) of aluminum under time-controlled voltage (U t ), time-controlled current density (j t ), and charge density-controlled voltage (U q ) modes. The effect of anodizing temperature and the modes on the optical properties of PAA-based photonic crystals (PCs) was analyzed in detail. It was shown that depending on the anodizing temperature, either broad or narrow bandpass filters can be produced with variable optical quality that depends strongly on the anodization mode and the parameters of the SPA function. Broad bandpass PCs (Q-factor < 10) tend to form during high-temperature SPA, with the first order photonic stop band (λ 1) at near infrared (NIR) region and almost 100% reflectivity and 0% transmittivity at the λ 1 in the PC produced under the U t mode. At these electrochemical conditions, the λ 1 peak broadens and become less intensive in the PCs formed under the U q , and j t modes. At low temperature, narrow bandpass filters are produced (Q-factor > 10), with the highest Q-factor (67) and PSB at NIR obtained during high-field SPA under the j t mode. The most intensive λ 1 was, however, attained during the high-field SPA under the U q mode, after post-process pore widening.