Plasmon-Induced Transparency and Refractive Index Sensing in Side-Coupled Stub-Hexagon Resonators

A nanoscale structure which comprises metal-insulator-metal (MIM) waveguide, stub resonator, and hexagonal resonator is proposed to realize plasmon-induced transparency (PIT) response. The characteristics of the device are numerically investigated with different geometrical parameters. Benefitting from the narrow transparency window and long coupling length between two resonators, the proposed devices are able to act as a nanosensor for refractive index (RI) sensing with figure-of-merit (FOM) of 178 and 140 RIU −1 near RI of 1 and 1.33, respectively. Furthermore, the FOM can be further improved by employing symmetric structure.