Preparation of photonic crystals made of air pores in anodic alumina

Photonic crystals made of air pores in anodic alumina were prepared by electrochemical oxidation of aluminium and subsequent chemical etching. Optical photographs and transmission spectra prove the existence of a photonic band gap in the optical sprectrum for this porous material. The colour of the sample and the diffraction peak position in the transmission spectra could easily be adjusted in the chemical etching process. This method could provide a possible approach to producing large-area optical photonic crystals cheaply and rapidly.