Surface Plasmon Resonance and Dielectric Core Effects on Two-Dimensional Periodic Arrays of Silver Nanospheres in a Square Lattice Embedded at Different Depths in a Silica Substrate

摘要

The dielectric core effects and surface plasmon resonance (SPR) modes of a two-dimensional (2D) periodic array of silver nanospheres (PASNSs) in a square lattice embedded at different depths in a silica substrate normally illuminated with the x-polarization plane wave are numerically investigated by using the finite element method with three-dimensional calculations. The unit cell of the 2D PASNSs examined is a unique structure, which is composed of a metallic nanoshell and a dielectric core (DC). Results show that the near-field optical properties and SPR modes obtained from the embedding cases of 2D PASNS are quite different from those of the solid cases of their counterpart, resulting in a field intensity increase and a redshift due to the plasmon hybridization of metallic nanoshells and their DCs. The strength of the hybridization depends on the geometry of the composite metallic nanoparticles and the surrounding media. On the basis of our simulations, we find two important parameters, i.e., the permittivity of the media filling DCs and the depth of the 2D PASNSs embedded in a silica substrate, which can affect the transmittance spectra and the position of SPR wavelengths. The intensity of transmittance spectra is reduced and the peak resonance is redshifted as the depth of the embedded 2D PASNSs is increased.