Blue LED-Pumped Broadband Short-Wave Infrared Emitter Based on LiMgPO₄:Cr³⁺,Ni²⁺ Phosphor

Blue light-emitting diode (LED) pumped short-wave infrared (SWIR; 900–1700 nm) emitters are providing new solutions in the design of portable and cost-effective infrared light sources for medical, surveillance, and spectroscopy applications by taking advantage of converter technology. However, desirable blue-light-excitable SWIR-emitting phosphors with a peak wavelength longer than 1000 nm are lacking. Herein, a promising broadband SWIR phosphor is designed and developed by incorporating Cr³⁺-Ni²⁺ ion pairs into LiMgPO₄ host. Upon 450 nm blue light excitation, the as-synthesized LiMgPO₄:Cr³⁺,Ni²⁺ phosphor exhibits a broad and intense SWIR emission spanning from 1100–1600 nm with peak wavelength at 1380 nm and a full width at half maximum of 273 nm due to the efficient energy transfer from Cr³⁺ to Ni²⁺. Moreover, phosphor-converted SWIR LED prototype device based on the combination of 450 nm blue LED chip and the optimized phosphor is fabricated as a new type of broadband illuminator covering the SWIR waveband, delivering a maximum radiant power of ≈2.7 mW at 120 mA driving current. Benefiting from the distinct spectral characteristics of SWIR light, the practical relevance of the fabricated SWIR illuminator is demonstrated in covert information identification and night vision lighting.