A high figure of merit refractive index sensor based on Fano resonance in all-dielectric metasurface

In this paper, we propose and numerically investigate a high figure of merit refractive index sensor with Fano resonance based on periodically arranged all-dielectric asymmetrical elliptical ring-disks. The electromagnetic field distributions and transmission spectra have been calculated to analyze the Fano resonances of our proposed structure. The sharp Fano peak can be easily tuned by adjusting the structural parameters. The maximum values of quality factor of the proposed structure can reach 4350. Furthermore, we find that the position of the Fano resonance is very sensitive to the change of the background refractive index. The sensitivity and FOM of the designed device can reach 541 nm/RIU and 2353 RIU-1, respectively. This study may open a new way for the development of nonlinear optics, integrated optical circuits and biosensing.