Terahertz sensor based on bound states in the continuum of an h-BN metasurface

An h-BN metasurface (MS) was designed to achieve a sensor based on bound states in the continuum (BICs). The Q -factor peak reaches 14,500 when the structure is symmetric. By introducing the asymmetry parameter δ , the quasi-bound state in the continuum (quasi-BIC) can be observed. Further analysis based on the multipole theory indicates that the toroidal dipole has the most significant influence on resonances. At the asymmetry parameter δ =0.2, the sensitivity of the resonance mode was 4.143 THz/RIU. Consequently, the h-BN MS has potential applications in the field of sensors.