High-Q multi-resonance refractive index sensor based on all-dielectric metasurface

Abstract All-dielectric metasurfaces enhance the interaction between light and matter, enabling precise control over the frequency, amplitude, and phase of light, as well as the generation of higher-order harmonics. The ultra-narrow linewidth resonance peaks generated in the transmission spectrum when light passes through metasurfaces can be utilized to design high-performance refractive index sensors and narrowband filters, among other optical devices. Due to its CMOS compatibility and low-loss characteristics, this paper designs a periodic all-dielectric metasurface composed of four rectangular Si 3 N 4 structures. When incident light is vertically illuminated along the z -axis of the metasurface, it generates up to five extremely narrow resonance peaks with modulation depths approaching 100%. The highest Q-factor among these peaks reach up to 13369. Through electromagnetic field analysis and multipole decomposition at the resonance peak wavelength, we observed the excitation of the Anapole mode. In the ambient refractive index range of n = 1.3 to 1.35, the sensitivity (S) of the metasurface reaches 479.8 nm RIU −1 , with FOM value of 2617 RIU −1 . Due to its simple structure and multiple resonances optical characteristics, the all-dielectric metasurface we designed exhibits higher accuracy and reliability in refractive index sensing, promising broad application prospects.