Nonreciprocal Circularly Polarized Lasing from Organic Achiral Microcrystals.

Organic materials are particularly appealing for circularly polarized (CP) lasers due to their remarkable chiroptical activities and exceptional optical gain properties. However, conventional organic CP lasers based on chiral molecules or microstructures typically exhibit reciprocal behavior, which complicates material synthesis and device fabrication for practical applications. In this study, we present nonreciprocal CP lasing from achiral organic microcrystals through the coupling between fluorescence linear anisotropy (f) and linear birefringence (LB), known as f-LB effect. By carefully controlling the crystallization process, we prepared triclinic and orthorhombic polymorphs with distinct molecular packing arrangements, which unlock the precise manipulation of f-LB coupling for efficient polarization state conversion of photons. The triclinic crystals exhibited stronger f-LB effect owing to the suitable angle between the emission plane and birefringence axis, resulting in robust nonreciprocal CP luminescence. More importantly, this coupling was further amplified during lasing oscillation, ultimately enabling nonreciprocal CP lasing with a dissymmetry factor of ∼1.0. These findings provide a novel approach to exploring high-performance nonreciprocal CP lasers and offer new insights into chiral photonics and optoelectronics.