Fabrication of one-dimensional photonic crystals with Al2O3/TiO2 by pulsed laser deposition

One-dimensional photonic crystal (1D PC) mirrors consisting of Al2O3/TiO2 stacks are theoretically and experimentally investigated at visible frequencies. In our experiments the refractive index of Al2O3 is tunable from 1.43 to 1.68. We found that the Al2O3/TiO2 combination can be adopted to fabricate both broad- and narrow-band 1D PC mirrors: Substituting nanoporous Al2O3 for dense SiO2 in an SiO2/TiO2 broad-band mirror yields the same spectral properties, while using dense Al2O3 in the combination can reduce the band-gap width to as low as 30 nm. The experimentally measured reflection and transmission spectra agree with the numerical results obtained by the transfer matrix method.