Multiple-Mode Bowtie Cavities for Refractive Index and Glucose Sensors Working in Visible and Near-Infrared Wavelength Range

Abstract A multiple-mode metal-insulator-metal plasmonic sensor with four coupled bowtie resonators containing two pair of silver baffles is numerically investigated using the finite element method and verified by the temporal coupled-mode theory. The proposed structure can function as the plasmonic refractive index and glucose sensors working in visible and near-infrared wavelength range. Simulation results show that introducing the silver baffles in bowtie cavities can modify the plasmon resonance modes and give a tunable way to enhance the sensitivity and figure of merit. The highest sensitivity (S) can reach S=1500.00, 1400.00, and 1100.00 nm/RIU and the high figure of merit (FOM) of 50.00, 46.67, and 36.67 RIU-1 from mode 1 to mode 3. The sensitivity obtained from three modes with operating wavelengths in visible and near-infrared simultaneously exceeds 1100.00 nm/RIU along with remarkably high FOM, which are not attainable from other reported literature. The proposed structure can realize multi-mode and shows impressive practical prospects that can be applied for integrated optics circuits (IOCs) and other nanophotonics devices.