Tunable Broadband Near-Infrared Luminescence in Glass Realized by Defect-Engineering

Tunable broadband near-infrared (NIR)-luminescent materials play a crucial role as light sources and tunable fiber lasers in modern technologies such as high-capacity telecommunication, imaging, and remote sensing. Despite considerable effort in studying the luminescent materials doped with rare-earth or transition metal ions, it is still challenging to achieve tunable broadband emission in photonic materials, especially in glasses, for active-fiber applications. In the present work, such NIR emission is achieved by modifying oxygen-deficient structural defects (i.e., singly ionized oxygen vacancies (V^•_O) in tellurium (Te)-doped germanate glass). The local glass chemistry around Te is controlled by engineering singly ionized oxygen vacancies (V^•_O) in alkali-alumino-germanate glass. This enables fine-tuning of the configurations and chemical states of Te centers over a wide range of chemical states, from ionic states to neutrally charged clusters and to positively charged clusters, resulting in various intriguing luminescent behaviors (e.g., wavelength-tunable emission, great emission enhancement, bandwidth extension).