Ultrahigh-Q chiroptical resonance metasurfaces based on merging bound states in the continuum (BICs) are investigated and numerically demonstrated. The destruction of C2 symmetry results in the leakage of BICs into… Click to show full abstract
Ultrahigh-Q chiroptical resonance metasurfaces based on merging bound states in the continuum (BICs) are investigated and numerically demonstrated. The destruction of C2 symmetry results in the leakage of BICs into quasi-BICs, and a chiral quasi-BIC is obtained by oblique incidence or continuous destruction of the mirror symmetry of the structure. Due to the significant topological properties of merging BICs, the Q factor (over 2 × 105) of the chiral resonance peak obtained is much higher than that of the previous work. Moreover, the proposed structure is easy to fabricate because no additional out-of-plane asymmetry is introduced. The proposed scheme is of importance in chiral biosensing applications.
               
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