Application of Periodical Nanostructures in Thin Metal Film for NearInfrared Multispectral Filters

Surface plasmonic nanostructures with cross-shaped-hole array in metal thin films are studied for multispectral filters, which cover visible to near-infrared wavelengths. Surface plasmons are induced from incident wave by the periodic arrays of nanostructures of the metal thin film, and then localized surface plasmon polaritons oscillate in the cavity, which is formed by two surfaces of metals through near-field excitation. The transmission spectra of light through these nanostructures are investigated with the finite-difference time-domain method; our simulations show that the features of the hole, and the periods of the array along with other parameters are critical to the optical spectral performance. The optical characterizations of our fabrications of these nanostructures milled by focused ion beam demonstrated very similar results of transmission spectra of simulation results. The simulations demonstrate he optical performance of the metal nanostructures, it is possible to obtain desired multispectral filters by programming parameters of those plasmonic nanostructures.