All-dielectric metasurface with multiple Fano resonances supporting high-performance refractive index sensing

All-dielectric metasurface has important application value in many fields, especially in refractive index sensing. In this paper, an all-dielectric metasurface composed of a silicon triangular-hole nanodisk array is designed and studied numerically. Through introducing asymmetry in the proposed metasurface and transforming the bound states in the continuum (BIC) into the quasi-BIC, three sharp Fano resonances with almost 100% modulation depth can be achieved, and the highest quality factor ( Q -factor) can reach 49,915. Further, the three Fano resonances can be regulated and controlled by adjusting the structural parameters. Moreover, the sensing performance of the structure is researched by changing the ambient refractive index. The maximum sensitivity obtained is 248 nm/RIU, and the best figure of merit is 3815RIU −1 . The proposed structure provides a scheme for the design of optical devices, especially refractive index sensors.