Enhanced Fano resonance for high-sensitivity sensing based on bound states in the continuum
Guang Feng, Zhihui Chen, Yang Wang, Xin Liu, Yinshan Liu, Xiao Liu, Fei Sun, Yibiao Yang, Shuqi Chen
Abstract
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 the continuum (BIC) can achieve high FOM, but they have some limitations in high sensitivity. Herein, we propose a periodic triple parallel metal bars structure to obtain high quality, a strong field, and multiple hot spots by the Friedrich–Wintgen BIC. Numerical results show the sensitivity and FOM can reach 1877 GHz/RIU and 665, respectively. Compared to the previously reported transmissive sensors based on BIC, the sensitivity has been greatly improved.