High-Q-factor multiple Fano resonance for sensitive refractive index sensors based on all-dielectric metasurface

High-performance sensors can be efficiently realized with an all-dielectric metasurface using high-Q-factor Fano resonance. In this study, a numerical analysis of an all-dielectric metasurface with two square holes and one rectangular hole was conducted. Multiple Fano resonances with a high Q-factor and modulation depth were excited by a toroidal dipole, an electric quadrupole, and a magnetic dipole by breaking the symmetry of the structure. According to the computed results, the modulation depth approached 100%, and the maximum Q-factor reached 90,048. The sensing performance of the structure is also discussed. The structure had a maximum sensitivity and figure of merit of 275 nm/RIU and 1833 RIU−1, respectively. Owing to the unique structure, multiple Fano resonances can be achieved, with applications in multiwavelength communication, multichannel nanosensors, and optical modulators. These resonances have high Q-factors, high modulation depths, and small linewidths.