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

A multiple-mode metal-insulator-metal plasmonic sensor with four coupled bowtie resonators containing two pairs 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 a plasmonic refractive index and glucose sensors working in visible and near-infrared wavelength ranges. 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.

Automated summary

The study investigates a multiple-mode metal-insulator-metal plasmonic sensor with four coupled bowtie resonators, showing high sensitivity and figure of merit in visible and near-infrared wavelength ranges. The proposed sensor structure demonstrates a tunable way to enhance sensitivity and FOM, surpassing results reported in other literature. This multi-mode sensor has practical prospects for integrated optics circuits and nanophotonics devices.