Research on high sensitivity fano resonance sensing based on MIM waveguide coupled with double Fibonacci spirals

In this paper, a metal-insulator-metal waveguide coupled with double Fibonacci spiral structure is designed and studied. The Fano resonance characteristics of the structure are analyzed in detail by means of transmission spectra and magnetic field distribution using finite element method. By changing the geometric parameters and refractive index, the sensing characteristics of the structure are quantitatively analyzed. This structure can be used in sensors, not only the sensitivity can reach an extremely high value of 3350 nm/RIU, but also the refractive index and peak wavelength show an excellent linear relationship. This structure provides a new scheme for the design of high sensitivity sensors. In addition, by measuring the refractive index of sodium chloride solution, it is proved that the structure has practical application prospect.