Enhanced localized plasmonic characteristics based on coaxial defective-disk and ring structures

Abstract

We have illustrated the localized plasmonic properties on the terahertz region based on a coaxial disk and ring structure (DRS) and a defective-disk and ring structure (DDRS). Two resonances can be observed in these coaxial structures, which arise from the anti-bonding and bonding resonance hybridization. Compared with DRS, an enhanced localized plasmonic effect at a higher-frequency resonance is observed on the DDRS, which is owing to a new strong dipole mode evoked at the edge of the wedge-shaped slice. Moreover, this higher-frequency localized plasmonic resonance of the DDRS could be further enhanced by increasing the depth of the wedge-shaped slice due to the coupling between the dipole resonance of the deeper wedge-shaped slice and the outer ring. Therefore, by using higher-order enhanced localized plasmonic characteristics, the designed DDRS is promising in sensing, spectroscopy and slow light effect.