Theoretical analysis of microring resonator filters made of plasmonic waveguides

Microring resonator filters which are made of dielectric-loaded surface plasmon polariton waveguides and operate in the telecommunication range are thoroughly analyzed by means of 3D-FEM simulations. The filters' functional characteristics, such as the resonant frequencies, the free spectral range, the transmission bandwidth and the extinction ratio, are investigated for different values of the key structural parameters, namely the ring radius and the gap separating the bus waveguide from the ring. In addition, the shift in the operating wavelength is quantified when the ring's refractive index is controlled as a result of thermal tuning.