Terahertz ultrasensitive biosensor based on wide-area and intense light-matter interaction supported by QBIC

A quasi-bound state in the continuum (QBIC) has unique attraction in optical switch, nonlinearity, communication, and sensing due to its ultrahigh radiation quality (Q) factor. The QBIC observed in metasurfaces also provides a feasible platform to achieve in-plane strong light-matter interaction, as well as to develop ultrasensitive biosensor. However, the existing metasurface designs are difficult to realize highly efficient excitation and high-performance sensing of QBIC in terahertz (THz) band. Here, we manipulate the interference coupling between electric quadrupole and magnetic dipole by introducing an asymmetry α into the metallic metasurface structure, which excites ultrahigh quality QBIC resonance with…