Plasmonic filter with highly selective wavelength in a fixed dimension based on the loaded rectangular ring cavity

Here we reported a compact plasmonic filter design based on the block-loaded rectangular ring cavity. The selected wavelength can be flexible modulated to longer ones without extending the filter dimension. Such filter was composed of a common rectangular ring and several loaded nanoblocks. This is attributed to the electrical field perturbation caused by the loaded block. The resonant mode was found sensitive to the nanoblock which located at the antinode position, and the proportional relationship was revealed between the selected wavelength and the nanoblock size and number, which ensured the accurate determination of the selected wavelength. In particularly, this proposed plasmonic filter possess a more compact size than the common used one for the same properties. These findings can be beneficial for the integrated optical circuit design and may improve the integration level.