Reconfigurable chiral quasi-bound states in the continuum metasurfaces based on an asymmetric interface

In this paper, a method to excite chiral quasi-bound states in the continuum (Q-BICs) using an asymmetric interface is proposed for the first time, to our knowledge. The chirality of a metasurface can be controlled by varying the medium of the active layer, achieving a maximum circular dichroism (CD) value of 0.9. Two types of reconfigurable chiral Q-BIC metasurfaces, a single-biased chiral Q-BIC metasurface (SBCBM) and a dual-biased chiral Q-BIC metasurface (DBCBM), are proposed, facilitated by the use of the electronically controlled material polyaniline (PANI). This enables electrically reconfigurable chiral Q-BIC with a maximum CD variability range from −0.9 to +0.9. These results highlight significant potential applications in fields such as reconfigurable devices, optical chiral switching, and environmental monitoring.