Laser-driven lighting technology is a remarkable innovation in the field of solid-state lighting. High-efficiency white light sources have been commercially produced, but laser-driven near-infrared (NIR) light source has not yet been captured, which hindered the numerous optoelectronic applications such as NIR spectroscopy and imaging techniques. Inspired by the observation that laser-driven lighting could break the limited power density and achieve effective output optical power density under higher incident optical power density, here, a novel NIR MgO:Cr3+,Ni2+ phosphor-in-glass film was prepared and combined on the sapphire substrate to fabricate laser-driven NIR light source. The results show that laser-driven NIR light source based on blue laser and MgO:Cr3+,Ni2+ phosphor-in-glass film combination could achieve a NIR output optical power density of 5.3 mW mm−2, which is 5 times higher than LED-driven NIR light source based on the same MgO:Cr3+,Ni2+ phosphor-in-glass film. Finally, we successfully demonstrated the potential applications of the as-fabricated laser-driven NIR light source in the field of night vision and high-penetration imaging. This finding provides an approach to achieving high-performance NIR light sources thereby opening up a new avenue for the exploration of NIR spectroscopy technology.
Bo-Mei Liu,Xiao-Xuan Guo,Lu-Yu Cao,Lin Huang,Rui Zou,Zhi Zhou,Jing Wang
The development of phosphor-converted light-emitting diodes (pc-LEDs) in the second near-infrared window (NIR-II, 1000–1700 nm) represents an important, newly emerging, and dynamic field in NIR spectroscopy. Unfortunately, lacking efficient NIR-II phosphors that can be excited by commercial blue LED chips impedes NIR spectroscopy applications. Herein, a donor–acceptor strategy is developed by introducing Cr 3+ sensitizers to greatly enhance the blue-light excitation efficiency of NIR-II-emitting MgO:Cr 3+ ,Ni 2+ phosphor. Consequently, a high-efficiency blue-light-excitable MgO:Cr 3+ ,Ni 2+ phosphor that gives a NIR-II emission at 1335 nm with a full width at half-maximum (FWHM) of 235 nm, is demonstrated. The product has a high internal quantum efficiency of 92.7 % and excellent thermal stability, maintaining 83.0 % of the room temperature emission intensity at 150 °C. Excitingly, the fabricated NIR-II pc-LED device shows a high NIR-II optical power (27.4 mW@350 mA). The performances of the achieved NIR-II pc-LED are almost the best results until now. Additionally, multifunctional applications including nondestructive detection and anti-counterfeiting of the NIR-II light source are demonstrated. These results are pretty crucial for the further development of NIR-II spectroscopy and imaging technology.
Near-infrared (NIR) phosphors activated by Cr 3+ ions hold significant potential for applications such as night vision and plant growth lighting due to their tunable emission properties governed by crystal field (CF) strength. In this study, Cr 3+ and Ti 4+ co-doped MgO phosphors were synthesized via a high-temperature solid-state reaction to modulate the NIR emission. Structural and optical characterizations revealed that Ti 4+ incorporation enhances the CF strength ( D q/ B ratio increases from 2.4 to 2.6), inducing a blue shift in the emission peak from 810 (MgO:Cr 3+ ) to 780 nm (Mg 0.8 Ti 0.2 O:Cr 3+ ) and with a strong sharp emission at 720 nm. The Ti 4+ doping also increases the fluorescence lifetime from 150.9 to 816.4 μs, attributed to altered Cr 3+ occupancy in octahedral sites and modified spin-allowed transitions. These findings demonstrate that Ti 4+ co-doping effectively tunes the NIR emission of MgO:Cr 3+ phosphors, offering a promising strategy for designing wavelength-adjustable NIR light sources.
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