Fig. 4: Applications based on laser-driven NIR-II light sources.

a Spatial resolution of our laser-driven NIR-II light sources based on MgO:0.3%Ni²⁺, 0.3%Cr³⁺ ceramic, determined by a standard line-pair card (lp/mm). b Modulation transfer function curves of our laser-driven NIR-II light sources based on MgO:0.3%Ni²⁺, 0.3%Cr³⁺ ceramic. c The photographs of a commercial silicon wafer with internal integrated micro-structure taken by a NIR camera under the obtained NIR-II light source and a visible camera under daylight (see the top left inset). d The photographs of an iron sheet on a plastic box: taken by a visible camera under daylight (d₁), and by a NIR camera in the dark (d₂) and (d₃–d₆) under exposure to our NIR-II lighting source at different blue laser power densities. e The grayscale variation trend of the NIR images of white-ring (solid dot line) of the plastic box and black-ring (solid square line) of the iron sheet and the contrast variation trend (solid star line) of the white/black ring NIR images, under exposure to our NIR-II lighting source at different blue laser power densities. Inset is the NIR image of the iron sheet on a plastic box under 2.86 W/mm² excitation