Rare Earth Single‐Atomic Hybrid Glasses for Near‐Infrared II Optical Waveguides

The increasing demands for modern information communication and storage necessitate the development of near‐infrared (NIR) active optical waveguides. However, achieving efficient NIR emission with minimal optical loss remains a critical challenge. Herein, we present a new class of rare earth single‐atomic hybrid glasses, synthesized via bottom‐up self‐assembly, as a solution to these limitations. By harnessing the ultralong phosphorescence of Nd3+ doped complex glasses, these materials achieve NIR‐II emission extending to 1.32 μm with a photoluminescence quantum yield (PLQY) of ~5.7%, setting a new record among state‐of‐the‐art rare‐earth based complexes in the NIR‐II region. This exceptional performance stems from the efficient sensitization of Nd3+ ions in hybrid glass, with a phosphorescence energy transfer efficiency of 93.55%. Furthermore, these transparent and flexible hybrid glasses trigger optical waveguiding in Eu3+‐ and Nd3+‐doped microstructures, enabling ultralow‐loss coefficients of 0.978 dB/mm at 819 nm and 5.1 dB/mm at 1048 nm, respectively. Therefore, this work not only demonstrates that metal–organic complex glasses with ultralong phosphorescence can effectively serve as sensitizer matrices for boosting NIR‐II emission, but also supports the fabrication of one‐dimensional (1D) and two‐dimensional (2D) glassy microstructures with ultralow‐loss optical waveguiding for advanced NIR‐II photonic applications.