Optical characteristics of pore size on porous anodic aluminium oxide films with embedded silver nanoparticles

Dielectric porous anodic aluminum oxide films embedded with two-dimensional silver nanoparticles arrays (porous Ag/AAO) have been fabricated by electrochemical anodization and deposition, wherein the position and rate of the Ag nanoparticles within the nanopores can be properly controlled. These porous Ag/AAO films have photo-induced plasmonic coupling and can be applied toward photo-absorption sensors. The plasmonic absorption is clearly visible and its absorption maximum red-shifts with increasing particle diameters. An investigation of how the absorption spectrum is influenced by systematically changing the pore diameter and inter-pore spacing is laid out. This work provides an approach to precisely tune the peak wavelength and the bandwidth of plasmonic absorption of porous Ag/AAO films utilizing fine control of the pore diameters. The wavelength shift slope of absorption peak with the pore diameter is measured to be approximately 0.82 nm/nm (peak wavelength/pore diameter). These tuning curves may be useful in the design of photon-response sensors and 2D tunable plasmonic-based nanostructure is expected to enable applications such as tunable photon-induced electrical conductivity.