Chiral Lasing Emission from a Simple Two‐Unit Supercell Metasurface

Abstract Circularly polarized light (CPL) sources are critical for applications in communication, chiral sensing, displays, and quantum computation. However, achieving narrow‐linewidth chiral lasing emission with high directionality and a significant degree of circular polarization (DCP) remains a significant challenge. Chiral metasurfaces leveraging optical bound states in the continuum (BICs) offer a promising solution by enhancing chirality and coherence. Nevertheless, the complexity of metasurface design and stringent fabrication requirements limit their practical application. This study presents a narrow‐linewidth chiral lasing with two opposite chiral states in off‐normal directions using a simple two‐unit supercell chiral metasurface. By integrating two unit cells with differently oriented notches, the in‐plane structural symmetry is broken, inducing spin splitting of the Γ 0 ‐BIC into Γ ±1 ‐modes. A high DCP of 0.95 is achieved at an emission angle of 36.0°. This simplified design offers an efficient and practical approach to realizing chiral lasing emission systems.