  A method to form the plasmonic lattice mode of periodic metallic nanoparticle
arrays is presented. In the arrays, each Ag nanosphere is on the top of a SiO2
nanopillar which sits on a quartz substrate. The simulated results show that,
in the wavelength range around the period of the arrays, the plasmonic lattice
mode can be formed. The transmittance of the structure varies rapidly from the
maximum to the minimum in a narrow wavelength band. This is attributed to the
wavelength-dependent diffracted waves generated by the periodic arrays and the
weak near-field coupling between Ag nanospheres and the quartz substrates.
Increasing the height of SiO2 nanopillars can weaken the near-field coupling
between Ag nanospheres and the quartz substrates, and lead to the greater
effects of the diffracted waves on the transmittance. As a result, the
plasmonic lattice mode can be optimized. This method provides a possible way to
promote the application of the plasmonic lattice mode.
