Reconfigurable phase-change metasurface for multifunctional control of chiral emission

In optoelectronics and photonics, developing multifunctional light-emitting devices has become a prominent research area. However, achieving integration of polarization control, intensity modulation, and tunability within a single device presents a formidable challenge. Here, we report the design and implementation of a symmetric bound state in the continuum (BIC) realized by a metasurface composed of perovskite nanobars on a silica substrate. Through the incorporation of both in-plane and out-of-plane symmetries, the BIC undergoes a transformation into a chiral quasi-bound state in the continuum (q-BIC). The chiral q-BIC metasurface exhibits an intrinsic chiral response, characterized by nearly perfect circular dichroism of 0.96, a key property for chiral optical applications. Furthermore, the integration of Sb2S3 phase-change materials into the metasurface enables dynamic regulation of resonant circularly polarized emission wavelengths between 760 and 820 nm, with selective enhancement of right circularly polarized emission by 240-fold and suppression of left circularly polarized emission. Our chiral q-BIC metasurface enables single-device multi-function integration, offering a versatile and dynamically tunable platform for enhanced chiral optical responses across optoelectronics and photonics.