Fano Resonance Biosensor of Asymmetric Splitting Ring in The-Band

Metasurface is a kind of artificial layered material whose thickness is less than the wavelength, which can flexibly and effectively control the polarization, amplitude, phase, polarization mode and propagation mode of electromagnetic waves. In this paper, a split ring metasurface structure with two openings is designed to excite Fano resonance by breaking the symmetry of the structure. Based on the finite element method (FEM), the asymmetric splitting ring of Thz metsurface is studied. It is shown that the peak value of Fano resonance and the quality factor (Q) can be modulated by changing the inner and outer diameters of the splitting ring. The Fano resonance is very sensitive to the asymmetry of the structure. A small asymmetry will excite the Fano resonance with high intensity, high quality factor and very narrow resonance linewidth. The refractive index sensitivity of the designed sensor reaches 7.23THz/RIU, and the Q value is up to 93.33. It can be used as a sensor to monitor the ambient refractive index, ambient temperature and liquid concentration.