Fano resonance in near-infrared metasurface based on asymmetric all-dielectric cylindroids

Recent research in all-dielectric asymmetric metasurfaces has demonstrated the capability to generate highly sharp Fano resonances, offering bright prospects for applications in optical biosensing. This work proposed a Fano Resonance in Near-Infrared Metasurface based on Asymmetric All-Dielectric Cylindroids. Each unit of the metasurface consists of two all-dielectric Si elliptical cylinders with different short-axis lengths arranged on top of an MgF₂ dielectric layer. By employing the Finite-Difference Time-Domain (FDTD) numerical analysis method, we investigate the optical characteristics of the metasurface. We found that when the semi-minor axis of the asymmetric cylindroids are 0.1μm(w₁) and 0.094μm(w₂), the metasurface exhibits a sharply narrow Fano resonance peak at λ=1.013μm, with a reflection intensity exceeding 92% and a Q-factor as high as 580. Which works at near-infrared region. The physical mechanism of the metasurface is the principle of electromagnetic coupling. The simulation results indicate that the Fano resonance arises from the interference of two distinct electric quadrupole modes. Moreover, the results demonstrate that the sensor exhibits a sensitivity of up to 85 nm/RIU, thereby validating its potential applications in areas such as biosensing and refractive index sensing.