Refractive index sensor based on bound states in the continuum in silicon-based metasurface

This article theoretically and experimentally investigates a silicon-based metasurface composed of a silicon cuboid with two sector nanopores. The simulation results demonstrate that breaking symmetry into the unit structure can achieve the quasi-bound state in the continuum (quasi-BIC) resonance modes with high quality factor (Q-factor). The spectral responses based on different refractive index results show a maximum sensitivity of 276 nm/RIU and a maximum figure of merit (FOM) of 1590 RIU−1. The structural parameters are adjusted to meet the requirements of different applications in the near-infrared spectral range. Based on the optimum sensing structure, a high-performance sensor is constructed with a refractive index (RI) sensitivity of 189 nm/RIU and FOM of 149 RIU−1. The proposed sensor has significant potential for various applications, including healthcare, environmental monitoring, and multi-channel biosensing.