A new approach to the synthesis of anodic titania photonic crystals with desired position and high reflectance of photonic band gaps

Anodic titanium oxide photonic crystals (ATO PhCs) are promising for optical sensing and photocatalysis due to their photonic band gaps (PBGs). The ability to control the spectral position and width of the PBG are essential for application of ATO PhCs. Anodizing charge density has recently been reported to be a main factor affecting the porosity and hence the effective refractive index (n(eff)) and PBG position of ATO PhCs. In this paper, we propose a method for accurate determining the dependence of n(eff) of ATO PhCs on the etching charge density varying in a wide range. The method is based on an analysis of the spectral positions of PBGs in photonic heterostructures. The obtained dependence was used for the synthesis of the ATO PhCs with desired PBG positions in a wide wavelength range (400-1500 nm) by the periodic voltage modulation on optical path length. The deviation of the experimental PBG position from the specified one does not exceed 10 %. The prepared PhCs possess similar to 100 % reflectance in the PBG region.

Automated summary

This study proposes a method for accurately determining the dependence of the effective refractive index of anodic titanium oxide photonic crystals on etching charge density, and uses this method to synthesize photonic crystals with desired photonic band gap positions.