Tunable multimode plasmonic filter based on asymmetric dual side-coupled U-shape cavities resonators

Abstract

In this paper, the plasmonic system composed of a Metal-Insulator-Metal (MIM) waveguide and dual asymmetric side-coupled U-shaped cavities is reported. It demonstrates that the strong coupling effect can lead to the opening of new transmission window. One of new peaks originates from the interference between the dual U-shaped cavities and bus waveguide, and the other is induced by the asymmetry of the structure, and each peak can be well tuned independently by changing the structural parameters of the U-shaped cavity. The effects of dielectric parameters on the transmission characteristics of the coupled system are also analysis, we find that the sensor sensitivity can reach 496 nm/RIU and a new sharp peak will exist in the short-wave region when dielectric parameter n = 1.2. By combining the magnetic field distributions, the internal physical mechanism is discussed. The proposed compact and simple plasmonic structure may have potential applications in nano-scale filter and other high density plasmonic integration circuits.