Near-infrared (NIR) phosphor-converted light-emitting diodes/laser diodes (LEDs/LDs) are prospective lighting sources for NIR spectroscopy. However, developing NIR phosphor materials with desired thermal robustness and high photoelectric efficiency is a crucial challenge for their applications. In this work, based on the cationic radius matching effect, a series of (Lu,Y)₃(Al,Sc,Cr)₂Al₃O₁₂ NIR phosphor ceramics (LuYScCr NIR-PCs) were fabricated by vacuum sintering. Excellent thermal stability (95%@150 ℃) was obtained in the prepared NIR-PCs, owing to their weak electron–phonon coupling effect (small Huang–Rhys factor). Being excited at 460 nm, NIR-PCs realized a broadband emission (650–850 nm) with internal quantum efficiency (IQE) of 60.68%. Combining NIR-PCs with LED/LD chips, the maximum output power of the encapsulated LED prototype was 447 mW@300 mA with photoelectric efficiency of as high as 18.6 %@180 mA, and the maximum output power of the LD prototype was 814 mW@2.5 A. The working temperatures of NIR-PCs were 70.8 ℃@300 mA (LED) and 102.8 ℃@3 A (LD). Finally, the prepared NIR-PCs applied in food detection were verified in this study, demonstrating their anticipated application prospects in the future.

Recently, high-performance color converters excitable by blue laser diode (LD) have sprung up for projection displays. However, the thermal accumulation effect of the color converters is a non-negligible problem under high-power LD irradiation. Herein, we developed novel opto-functional composites (patterned CaAlSiN₃:Eu²⁺ phosphor-in-glass film–Y₃Al₅O₁₂:Ce³⁺ phosphor-in-glass film@Al₂O₃ plate with aluminum "heat sink" ) via a thermal management methodology of combining "phosphor wheel" and "heat sink" for a lighting source of highpower laser projection displays. This new composite design makes it effective to transport generated thermal phonons away to reduce the thermal ionization process, and to yield stable and high-quality white light with brightness of 4510 lm@43 W, luminous efficacy of 105 lm/W, correlated color temperature of 3541 K, and color rendering index of 80.0. Furthermore, the phosphor-in-glass film-converted laser projection system was also successfully designed, showing a more vivid color effect compared to a traditional LED-based projector. This work emphasizes the importance of the thermal management upon high-power laser irradiation, and hopefully facilitates the development of a new LD-driven lighting source for high-power laser projection displays.

Particle velocimetry based on the temporal feature of upconversion luminescent nanocrystals is a newly-raising fluid velocimetry. Exploiting the availability to low flow rate fluid and exempting redundance external calibration (achieving once calibration for all) are highly expected and challenging. Herein, an engineered core–shell nano-probe, NaYF₄:Yb/Ho/Ce@NaGdF₄, was proposed, in which the Ce³⁺ ions were utilized to manipulate the upconversion dynamic of Ho³⁺. Through optimization, a superior sensitive against low-speed flow is achieved, and the external calibrations before each operation can be avoided. Application demonstrations were conducted on a fluid circulation system with controllable flow rate. The fluid velocity was monitored successfully, no matter it is permanent, or cyclically variating (imitating the in vivo arterial blood). Moreover, this velocimetric route is competent in spatial scanning for handling the spatially inhomogeneous velocity field. Such sensing nanomaterial and fluid velocimetric method exhibit promising application potential in human blood velocimetry, industrial control, or environmental monitoring.