Filtering Property Based on Ultra-Wide Stopband in Double Sector/Sectorial-Ring Stub Resonator Coupled to Plasmonic Waveguide

A double sector or sectorial-ring stub resonator coupled to a plasmonic waveguide is proposed and investigated. This resonator is built with two same stubs that are symmetrically arranged together, which has the advantages of realizing asymmetrical single stub and forming no-distance double stub. The characteristic spectral responses of the two novel systems are simulated by using the finite-difference time-domain method. The results show that an ultra-wide stopband is achieved, and a multiple double stub is realized by altering the structure size of the double stub that plays important role in the stopband phenomenon. A tunable stopband, a specific filtering waveband and an optimum structural parameter are obtained by adjusting the inner radius (
r
), (outer) radius (
R
), or central angle (
θ
) of the double stub. The wavelength and bandwidth of the stopband have various variations with the changing of
r
,
R,
or
θ
, and the stopbands in the two systems have similar changes and different features. This paper provides a promising application for band-stop nanofilters and plasmonic integrated optical circuits.