Enhanced Fano resonance for high-sensitivity sensing based on bound states in the continuum

Although previously reported terahertz absorbers can achieve high-sensitivity refractive index sensing, the resonant peak is too broad, which leads to a low figure of merit (FOM). Transmissive sensors based on bound states in continuum (BIC) high FOM, but they have some limitations sensitivity. Herein, we propose periodic triple parallel metal bars structure obtain quality, strong field, and multiple hot spots by Friedrich–Wintgen BIC. Numerical results show sensitivity FOM reach 1877 GHz/RIU 665, respectively. Compared transmissive BIC, has been greatly improved.