Sharp plasmonic resonances based on coupling of high order localized resonance and lattice surface mode in meta-molecules

摘要

The coupling between the high order localized resonant mode and diffraction mode in meta-molecule arrays consisting of three identical split ring resonators (SRRs) in each cell was demonstrated numerically with finite difference time domain method. By introducing both the near-field interaction and diffraction coupling mechanism, two types of interesting resonant modes are observed. One is the excitation of the second and the third-order plasmon resonance simultaneously with linear polarized light at normal incidence. The other one is a dark plasmonic state with sharper line shape produced by the third-order plasmon resonance and diffraction coupling. These resonant modes based on the 'designed' coupling scheme present higher quality factors than those in hybridized plasmonic state due to the electric dipole interaction, which is of great interest for application in the field of nanophotonic devices such as sensing, detector and spaser.