Theoretical Analysis of Sub-Wavelength Light Propagation Through the Double-Chain Silver Nanorings

Surface plasmon resonance effects on a system consisting of the double-chain silver nanorings are numerically investigated by means of the finite element method with three-dimensional calculations. The numerical results for resonant wavelengths corresponding to different light polarizations, pair numbers, illumination wavelengths, charge distribution and the permittivities filled inside the dielectric holes are reported as well. Results show that the double-chain silver nanorings exhibit tunable plasmon resonances in the near field zone that are not observed for the silver nanodisks of the same volume. The resonance wavelength is redshifted as the filling medium in dielectric holes increases, which is attributed to a longer effective optical path. It can be verified that the proposed structure (e.g., twelve pairs or more pairs) is pertinent to the functionality of long range of wave guiding and also show promise for applications in nanooptical devices, sensing, and surface-enhanced spectroscopy, due to their strong and tunable plasmon resonance.