Perfect two-dimensional porous alumina photonic crystals with duplex oxide layers

A perfect two-dimensional porous alumina photonic crystal with 500 nm interpore distance is fabricated on an area of 4 cm(Super 2) via imprint methods and subsequent electrochemical anodization. The results indicate that the porous alumina structure is composed of a duplex oxide layer, an inner oxide layer consisting of pure alumina oxide of 50 nm in thickness, and an outer oxide layer of nonuniform refractive index.