Ultrasensitive sensing based on quasi-bound states in the continuum with terahertz metamaterial

The exceptional resonances excited by quasibound states in the continuum (QBIC) offer great potential in high-sensitivity sensing applications. Here, we demonstrate a terahertz metamaterial sensor based on the excitation of high-quality QBIC resonances by introducing asymmetries in a metallic metamaterial structure. The resulting sensor features a quality (Q) factor up to 110.6 and a refractive index sensitivity up to 439 GHz/RIU.