High-power broadband NIR light sources are desired for non-invasive imaging and quantitative detection applications. This work reported tunable NIR emission from 686 to 928 nm via the control of local structural symmetry around isolated Cr3+ ions in MgAl2O4:Cr3+ translucent ceramic, further realizing the optimized external quantum efficiency of 73% and laser-driven broadband NIR output power above 2 W toward heart rate monitoring.
Abstract
High-power broadband near-infrared (NIR) light sources have attracted extensive interest toward emerging non-invasive imaging and detection applications. However, exploring highly stable luminescent materials with targeted broadband NIR emission remains a great challenge. Here, MgAl2O4:Cr3+ translucent ceramics have been designed and fabricated by a spark plasma sintering method, and a giant redshift of the emission band occurs from 686 to 928 nm due to the decreasing local structural symmetry around the isolated Cr3+ ions induced by the abundant cation vacancies. As Cr3+ content increases, MgAl2O4:6%Cr3+ ceramic realizes the optimized external quantum efficiency of 73% with broadband NIR emission centered at 890 nm and a full-width at half-maximum of 315 nm under 450 nm excitation. The next-generation laser-driven light source containing NIR ceramic provides an output power exceeding 2 W and a light conversion efficiency of 22% when pumped with a blue laser of 10 W·mm−2. The proof-of-concept demonstrations in imaging and detection reveal the advantages of high-power and high-efficiency laser-driven broadband NIR light sources and promote future development in the chemical design of NIR emitters.
InfoMat, EarlyView. Read More
