Fabrication of nanoporous anodized aluminum oxide based photonic crystals with multi-band responses in the vis-NIR region.

Photonic crystals (PC) play a key role in optical field modulation due to their unique photonic band gaps (PBGs). Anodic aluminum oxide (AAO) prepared by pulse anodization is a promising candidate for PC devices. In this research, an AAO-based PC with multi-band was fabricated on a single-slice & single-material film, which exhibits multi-band responses in the visible-to-near-infrared (vis-NIR) region. In other words, multiple PBGs present simultaneously at different wavelength ranges and can be precisely controlled by the experimental protocols. The deposition of a silver layer by a simple physical vapor deposition (PVD) method further modulates the refractive indices of the AAO-based PC, enabling the fabrication of well-distributed Bragg reflector (DBR) structures with tunable optical Tamm states (OTS). The prepared AAO-based PC can work as single-slice & single-material devices with excellent properties and broad application prospects in anti-counterfeiting and selective optical filtering.