Design of simple, ultrasensitive, and tunable teraherz metasensors based on quasi-BIC

A brand new hybrid metasurface cell consisting of a simple apron-shaped structure layered with photosensitive silicon is proposed with a Q-value of 1.43 × 104 by optimizing the structure, which achieves bidirectional and continuous regulation of the quasi-BIC and BIC through the excitation of the photosensitive material by a pumped light source. With an unprecedented optical quality factor Q of 4.13 × 104 under the final strong light modulation. Then, the dominant role of the electric quadrupole (EQ) on the BIC and high-intensity quasi-BIC resonances of the symmetrical protected state is explored and verified. The refractive index sensing sensitivity after modulation is 142.77GHz/RIU. The figure of merit (FoM) is increased from 3268 to 8923, which is the highest value of the current theory, providing desirable ideas for narrowband filtering, high sensitivity sensing and biomolecular identification.