One-dimensional alumina photonic crystals with a narrow band gap and their applications to high-sensitivity concentration sensor and photoluminescence enhancement

One-dimensional (1D) anodic aluminum oxide (AAO) photonic crystals (PCs) with alternate arrangement of stem channel layer and branched channel layer have been fabricated by using modified periodic pulse anodic technique with simple voltage waveform, and exhibited a narrow stop band with extreme low transmittance, steep edge. Their stop band is very sensitive to the concentration of NaCl solution, and the PCs are very suitable for concentration sensors. Importantly, it also is found that the photoluminescence (PL) intensity is enhanced remarkably when the PC structure was introduced into the AAO, which mainly attributes to the introduction of more PL centers into the branched channel layers, and the stop band also has effect on the PL intensity. Especially, the blue band edge of the stop band plays more important role on the PL enhancement of AAO.