MgAl 2 O 4 :Cr 3+ translucent ceramics with tunable broadband near‐infrared luminescence for laser‐driven light source detection

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, MgAl 2 O 4 :Cr 3+ 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 Cr 3+ ions induced by the abundant cation vacancies. As Cr 3+ content increases, MgAl 2 O 4 :6%Cr 3+ 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. image