High-Q factor terahertz metamaterial sensor based on quasi-BIC

In this paper, we proposed a terahertz (THz) metamaterial sensor, which consists of an array with two mirrored double split ring resonators (DSRRs) in one unit cell deposited on a lossless polyimide substrate. The THz spectral response show that when the two DSRRs in one unit cell are mirror symmetric and center symmetric simultaneously, two types of symmetry-protected bound states in the continuum (BICs) can be generated with the incident polarization unchanged. When the gaps are on the short or long arms of DSRRs, different modes of BIC can be observed. By breaking the symmetry of the structure with the gaps deviating from the center line of the DSRRs, quasi-BICs can be achieved, which can provide high Q-factors for our designed THz metamaterial sensor. The performance of the sensor is also evaluated, which has the characteristics of high Q-factor, high sensitivity, and high linearity. The integration of quasi-BIC and THz sensing technology will help solve the problems faced in the design of ultra-high Q-factor THz sensors and further expand the applications of terahertz technology.