Research on highly sensitive and independently tunable sensing in MIM waveguide structure based on Fano resonance

In this paper, a highly sensitive sensing in metal–insulator–metal waveguide structure that can be tuned independently is designed and studied. Using the finite element method, the transmission spectra and magnetic field distribution are studied, and the Fano resonance characteristics are obtained. By changing the geometric parameters and refractive index, the sensing characteristics of the structure are analyzed. The sensitivity of the two peaks of the structure can reach extremely high 2780 nm/RIU and 3580 nm/RIU, and there is an excellent linear relationship between the refractive index and the peak wavelength. The two peak wavelengths do not affect each other, and the independent tuning can be achieved. This structure can measure two quantities meanwhile with high precision and high efficiency, which provides a new scheme for the design of nanosensors. In addition, by measuring the concentration of sodium chloride solution and glucose solution, it is proved that the structure has the prospect of practical application.