Plasmonic Sensor with Interconnected Dual Ring Resonator for Refractive Index Sensing

This study proposes a highly sensitive plasmonic sensor utilizing a Metal-Insulator-Metal (MIM) waveguide incorporating a stub-connected circular dual-ring resonator. The sensor consists of two rectangular waveguides coupled with a stub-connected double ring resonator, where the electromagnetic (EM) wave appears at the output port only when resonance occurs within the resonator at a specific wavelength. The sensor's performance is assessed through computational modeling using the Finite-Difference Time-Domain (FDTD) technique. The results reveal four distinct sensitivity peaks across the visible and near-infrared wavelength ranges. By refining geometrical parameters such as the radius of the ring, the optimized sensor achieves a peak sensitivity of 2063 nm/RIU around peak 4 in the near-infrared region. It's remarkable ability to identify even the tiniest shift in refractive index makes it highly effective for biosensing applications.