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 Γ₀-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.