Fig. 1. Diagrams of SRR structure and BIC field distribution. (a) Diagram of SRR dimension; (b) Distribution of x component of BIC electric field in superlattice ①; (c) distribution of x component of BIC electric field distribution in superlattice ②; (d) field mode distribution near SRR in BIC; (e) diagram of designed structure

Fig. 2. Diagrams of QBIC under different structural asymmetric degrees. Schematics of superlattices (a) ① and (b) ② after breaking structural symmetry; transmission spectra for superlattices (c) ① and (d) ② under different δ_g ; color maps of transmission spectra corresponding to (e) BIC I and (f) BIC II under different asymmetric degrees

Fig. 3. Diagrams of resonance field distributions in asymmetric structures and relationship between Q and asymmetric degree. (a) Distributions of x components of electric fields for different resonances;(b) transmission spectrum of superlattice ① when δ_g= 4 μm; (c) relationship between Q and asymmetric degree

Fig. 4. Electric field distributions of BICs in superlattice ③ and transmission spectra in asymmetric structure. (a) Electric field distribution of BIC at 0.380 THz; (b) electric field distribution of BIC at 0.425 THz; (c) diagram of superlattice ③ after breaking structural symmetry; (d) transmission spectra after breaking structural symmetry; (e) color map of transmission spectra

Fig. 5. Relationship between QBIC and ohmic loss of metal materials. (a) Transmission spectra of superlattices ① composed of different metals; (b) conductivity of metal materials calculated by Drude model

Fig. 6. Relationship between BIC / QBIC and incident angle. (a) Diagram of incident angle; (b) Q of QBIC versus incident angle; (c)$-$(f)variation of transmission spectrum of superlattice ① with incident angle

Fig. 7. Variation of transmission spectrum of superlattice ② with incident angle