Single/multiple-mode-selection optical nanofilters based on end-coupled split-ring resonators

摘要

A plasmonic mode-selection filter based on end-coupled circular split-ring resonators is proposed and demonstrated. In contrast to regular ring resonators, which can support only the integer modes, extra noninteger resonance modes will be excited by placing metallic nanowalls in the proposed circular ring resonators. Since all the modes are highly sensitive to the position of the nanowall, the associated modes are effectively excited or suppressed by manipulating the position. This proposed scheme offers great flexibility to design the transmission spectrum with expected modes. Moreover, each integer or noninteger resonance mode with high transmittance can be selected individually by cascading two proposed split-ring resonators that share an intersection of transmission peaks. The corresponding spectra and the propagation characteristics are numerically investigated by using the finite-difference time-domain method.