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Combining with the bound states in the continuum (BICs) theory in all-dielectric metasurfaces has become an extensively used method to excite multiple high quality(Q) factor Fano resonances, which remarkably enhance the performance of structures to be applied to refractive index sensors. In this paper, a novel silicon pinwheel-shaped all-dielectric metasurface in the near-infrared region is designed and numerically investigated. Two Fano resonances are excited in the original structures. After breaking the symmetry of the original structures in combination with the BIC theory, four sharp Fano resonances are excited and the maximum Q-factor exceeds 3.9 × 10 5 when δ = 10 nm. With the asymmetric parameter δ = 80 nm, multiple Fano resonances could be turned on and off by turning the polarization of the incident light, which performs excellent characteristics in optical switches. Both in the original structures and in the asymmetric state it offers outstanding sensing characteristics. Furthermore, with δ = 80 nm and the polarization angle 90 degrees, the sensitivity and the figure of merit (FOM) could respectively reach up to 355 nm/RIU and 1375.97 RIU -1 . The designed structures may provide a way to enhance the performance of bio-chemical sensors, optical switches, and nonlinear optics.

Fano resonance with high Q-factor can greatly enhance the light–matter interaction in all-dielectric metasurface, which is an important condition for developing high-performance micro-/nano-photonics devices. In this paper, we present an all-dielectric metasurface structure composed of nanoarrays to investigate the properties of BIC realization and Fano resonance in the near-infrared spectral region. Four Fano profiles are generated, and two quasi-BIC resonance modes excited by MD appear when the structural symmetry is broken. All the Fano resonances modulation depth close to 100%. The spectral response of the proposed structure is also highly tunable by adjusting the polarization of the incident light and the geometric parameters of the structure. This work may provide a reference for the design of devices, such as biochemical sensing, optical switches, and optical modulators.

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