Broadband Near‐Infrared Fibers Derived from Nanocrystal‐Glass Composites for Miniature Arrays Light Sources

Abstract Broadband near‐infrared (NIR) fiber arrays are highly desirable for multiplexed fluorescence endoscopic, however, there is a challenge for the development of miniature light sources with highly efficient broadband NIR emissions. Here the synthesis of a MgAl 2 O 4 :Cr 3+ nanocrystal‐glass composite (NGC) with an Cr 3+ ‐clusters‐induced broadband NIR emission possessing is presented and external quantum efficiency of 44% and a full width at half maximum of 297 nm, and the NGC fiber is further fabricated through a template solidification strategy, resulting in the construction of an all‐fiber coupling system by fusing them with commercial quartz fiber that achieves an optical coupling efficiency of 95.2%. Furthermore, these NGC fibers are regularly arranged into fiber bundle as an array light source to enhance NIR luminescence and imaging ability, and the fluorescence imaging of 4 mm biological tissue penetration is realized, as well as the multiplexed fluorescence imaging, under the irradiation of the NIR fiber bundle. This study provides general and efficient fiber fabrication guidelines toward NIR array light sources, opening the new routes for fluorescence endoscopes.