Ordered and Anisotropic Assembling of Au ₂ Ag ₂ Parallelogram Enables Multi‐Directional Low‐Loss Optical Waveguide

Abstract Optical waveguide materials serve as fundamental building blocks for integrated photonic systems, which have a wide range of applications in optical communications. Micro‐crystals as active optical waveguide materials can provide the technical foundation for achieving small‐sized and high‐density integrated devices. However, how to achieve planar anisotropy and multi‐directional optical waveguides in 2D crystals remains challenging. Herein, Au 2 Ag 2 ( R / S ‐POT) 4 (POT: 4‐phenyloxazolidine‐2‐thione) with blue circularly polarized luminescence (CPL) emission at 455 nm and photoluminescent quantum yield (PLQY) up to 93.5% is designed. Parallelogram Au 2 Ag 2 core induces orientation arrangement of peripheral ligands and further promotes regular 2D stacking, enabling crystals to form high crystallinity and smooth surfaces. Crucially, the chiral structure promotes highly anisotropic molecular packing in the formed 2D crystal, which leads to the induction of anisotropy in the ordered packing direction by the parallel orientation transition dipole moment (TDM), with a linear polarization ratio of 0.61. Meanwhile, 2D crystals exhibit direction‐dependent waveguide characteristics with optical loss coefficient (OLC) of 0.01 (D1), 0.0178 (D2), and 0.0161 dB µm −1 (D3), respectively. This work not only establishes a feasible strategy for anisotropic waveguides of 2D clusters but also introduces 2D micro‐structures that hold promising potential for applications in information encryption.