Surface Plasmon Filter Based on Metal–Insulator-Metal Waveguide with Multi-Stopband and High Filtering Efficiency

In order to meet the demand for multi-stopband filters and high filtering efficiency in optical nanodevices, a surface plasmon band-stop filter coupled with a straight waveguide and an arch-type resonator is proposed in this paper. Simulation analysis of visible and near-infrared spectra and field distribution using the finite element method shows that the transmittance spectrum of this structure has five stop bands in the 800 nm band range with a minimum transmittance of 9.10%; when the key parameters such as the bottom size of the resonant cavity are changed, the transmission curves are red-shifted and the performance of some of the stop bands is significantly enhanced; the sensitivity, quality factor and figure of merit can reach 1780 nm/RIU, 108.86 and 102.49 RIU⁻¹, respectively. Finally, two optimized structures are proposed to further enhance the filter performance, allowing a minimum transmittance as low as 0.41%. The filter has a wide application prospect in optical integrated circuits.