Enhanced plasmonic waveguide sensing performance with a semicircular-ring resonator

摘要

In this study, a plasmonic refractive index sensor composed of a semicircular ring resonator embedded with silver nanorods (AgNDs) and a metal-insulator-metal (MIM) bus waveguide was developed. The designed system has the advantage of a shorter optical path than a regular circular resonator. Consequently, its size is half that of a typical one. In addition, the basement of the resonator can offer a more extended coupling interface facing the bus waveguide, increasing the gap plasmon resonance between the incident light and AgNDs. The finite element method (FEM) comprehensively simulated the transmittance and electromagnetic wave characteristics. The size of the AgNDs was found to be the main factor influencing the gap plasmon mode in the resonator and contributed to the increased sensitivity of the structure. Compared with its standard counterpart, the designed structure can increase the sensitivity of the device by 223.07%. The calculated maximum sensitivity was 2900 nm/RIU. This work paves the way for designing sensitive plasmonic sensors and could be rival candidates for sensing applications.