Glass Composite Fiber for Broadband NIR-II Mini Light Source

Near-infrared second window (NIR-II, 1000-1700 nm) light sources present remarkable scientific and technological promise, with wide-ranging applications spanning biomedical imaging, biosensing, and related fields. However, most of the available candidates are in bulk form and it is urgently required to develop mini light sources. Herein, a broadband NIR-II mini fiber-type light source equipped by Ni²⁺ activated glass composite fibers is proposed and investigated. It is shown that the transparent glass composite exhibits broadband NIR-II emission with a full width half-maximum approaching 240 nm and an internal quantum efficiency (IQE) larger than 50% by rational control of nanocrystallization. Additionally, the corresponding glass composite fibers are prepared, demonstrating efficient broadband response and distinct on-off gain in NIR-II region. Benefited from above features, an all-fiber mini light source by fusing glass composite fibers with commercial passive fibers is successfully constructed and demonstrates its promising applications for NIR-II imaging. These findings demonstrate significant progress in the development of NIR-responsive photonic materials, enabling advanced applications in photonic technology.