Engineering the plasmonic optical properties of cubic silver nanostructures based on Fano resonance

The plasmonic optical properties of nanostructures including a dimer, a linear chain, a T-shaped nanostructure, and a 2D array consisting of Ag nanocubes have been investigated using the discrete dipole approximation method. The simulation results indicate that both the interparticle gap and polarization have an important impact on far-field and near-field characteristics. With decreasing interparticle distance for four nanostructures, the plasmon resonance peak is monotonically red-shifted and the electric intensity enhancement factor increases rapidly due to increased interparticle coupling interaction. Moreover, we also find that a T-shaped nanostructure has the largest electric intensity enhancement factor compared with other three nanostructures due to the coupling interaction at the intersection. This coupling is caused by the radiative interference between subradiant and superradiant resulting in Fano resonance. These results show how nanostructure arrangement design, gap adjustment, and polarization control can be used to achieve high field enhancements.