Integrated NIR-Ⅱ light sources via Cr⁴⁺-doped wafer-scale composite ceramics for enhanced image sensing

Near-infrared-Ⅱ (NIR-Ⅱ) photons hold great potential in assisting non-invasive imaging and optical signal sensing. However, the integration of broadband NIR-Ⅱ light sources with photodetectors to improve the imaging sensitivity and spatial resolution is highly demanded. Herein, we have developed MgO–Li₂SrGeO₄:Cr⁴⁺ composite ceramics, which demonstrate a broad NIR-Ⅱ emission band centered at 1160 nm originating from spin-allowed ³T₂ → ³A₂ (³F) transition of Cr⁴⁺. The incorporated nano-MgO particles serve as light-guiding channels while filling the pores and prevents the reduction of Cr⁴⁺, enhancing the external quantum efficiency and thermal conductivity of the composite ceramics to 53% and 17.8 W·m⁻¹·K⁻¹, respectively. The dynamic wafer-scale luminescent ceramic wheel delivers a record broadband NIR-Ⅱ emission output power of 1.9 W under 20 W·mm⁻² red laser excitation, which facilitates imaging sensing of commercial PbS photodetectors by enhancing their photocurrents and signal-to-noise ratios. These results establish the feasibility of high-power broadband NIR-Ⅱ light sources integrated with photodetectors, and further demonstrate the combination of intelligent algorithms toward high-resolution optical imaging.