Plasmonic-induced transparency and unidirectional control based on the waveguide structure with quadrant ring resonators

In this paper, a metal-insulator-metal straight waveguide structure with quadrant ring resonators (QRRs) is theoretically presented. The transmission spectra at output ports are studied by the finite element method (FEM). The simulation results show great filtering effects at specific wavelengths. In order to unidirectionally control plasmonic flows at waveguide junctions, the original design has been expanded to T- and X-shaped waveguides with the QRRs. The results reveal that obvious Fano effects can be achieved in T-shaped systems.