High-performance tunable fano resonance refractive index sensor based on a double T-type all-dielectric metasurface

Abstract

Abstract An all-dielectric metasurface dual operating bands sensing structure based on a double-T-type silicon block is proposed, which realizes multifunctional sensing properties by modulating the symmetry of the structure. In the asymmetric configuration, the structure exhibits excellent sensing performance in the refractive index range of 1.0–1.1, with a sensitivity and figure of merit of 643 nm RIU −1 and 1537 RIU −1 , respectively; by establishing a quantitative relationship between air pressure and air refractive index, the structure also realizes high-precision air pressure sensing, and exhibits a high accuracy of 1.88 nm MPa −1 within the air pressure range of 100–900 kPa. When the structure is adjusted to a symmetric configuration and the angle of incidence is adjusted, the ultra-high sensitivity (1913 nm RIU −1 ) and excellent figure of merit (911 RIU −1 ) for biomolecules in the refractive index range of 1.33–1.40 can realize high-precision detection of biological samples, such as blood components. This study not only provides a new idea for excitation of quasi-BIC (Bound State in the Continuum) modes, but also expands the prospect of the application of metasurfaces in air pressure sensing and biomedical detection, and provides an important reference for the development of high-performance sensors.