The transmission characteristics of surface plasmon polaritons in ring resonator

A two-dimensional nanoscale structure which consists of two metal-insulator-metal (MIM) waveguides coupled to each other by a ring resonator is designed. The transmission characteristics of surface plasmon polaritons are studied in this structure. There are several types of modes in the transmission spectrum. These modes exhibit red shift when the radius of the ring increases. The transmission properties of such structure are simulated by the Finite-Difference Time-Domain (FDTD) method, and the eignwavelengths of the ring resonator are calculated theoretically. Results obtained by the theory of the ring resonator are consistent with those from the FDTD simulations.