Recently, a team led by Professor Xia Zhiguo at the State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, reported the development of a new generation of blue laser-driven near-infrared light source devices using a remarkably simple MgO:Cr3+ near-infrared fluorescent transparent ceramic. Achieving a record-breaking output power of 6W, this innovation has shown great potential in applications such as long-distance night vision supplementary lighting and non-destructive testing imaging. The findings were published online in Nature Photonics.
The advent of blue light-emitting diodes (LEDs) heralded the fourth generation of semiconductor lighting technology. New application demands have set higher standards for light source devices, making blue laser diodes (LDs) combined with fluorescent conversion materials a significant direction for development. Unlike LED sources, this new generation of laser fluorescent light sources is made by pumping fluorescent conversion materials with very bright blue LDs and holds immense potential for use in aviation and maritime lighting, underwater lighting, laser fluorescent display projectors, and high-power near-infrared light source devices.
This research introduced a "nearly perfect" performance, highly stable MgO:Cr3+ fluorescent transparent ceramic, achieving an emission peak at 810nm with the highest external quantum efficiency (81%) recorded so far. The doping of Cr3+ ions in the Mg2+ lattice positions introduces abundant cationic vacancy defects, creating various local environments for Cr3+ luminescent centers.
Furthermore, the phonon-assisted excitation state energy transfer process between luminescent centers compensates for the non-radiative relaxation at longer wavelengths, overcoming the influence of the bandgap rate and enhancing the luminous efficiency. Benefiting from the ultra-high thermal conductivity of MgO fluorescent transparent ceramics, an outstanding broadband near-infrared output power exceeding 6W was achieved under 22W/mm2 blue LD pumping, with a light conversion efficiency of 29%.
Professor Xia Zhiguo, the corresponding author of the paper, stated that this technology has been granted a national invention patent (ZL202211147958.4). The prototype devices employing this technology promise broad application prospects in long-distance night vision supplement, industrial flaw detection equipment, and non-destructive testing imaging for medical instruments.
This research was supported by the National Natural Science Foundation of China, the National Key R&D Program, and the Guangdong Pearl River Talent Plan.
For more information on the paper: https://doi.org/10.1038/s41566-024-01400-7
