Unidirectional Reflectionless Propagation in Plasmonic Waveguide System Based on Phase Coupling Between Two Stub Resonators

A scheme on unidirectional reflectionless propagation is theoretically investigated in a plasmonic waveguide system which consists of two metal–insulator–metal (MIM) stub resonators side coupled to an MIM plasmonic waveguide. By appropriately tuning the phase difference between two stub resonators, unidirectional reflectionless propagation at exceptional point, phase transition, and coherent perfect absorber are realized. Moreover, in both directions, reflectivity for one side is close to 0 and for the other side approximates to 0.8.