High-brightness laser-driven light sources, which are generated by exciting phosphor materials with high power density blue laser diodes, hold great promise for applications in long-distance searchlights, high-luminance projection displays, and long-range night vision systems. The luminance of these light sources is primarily influenced by two critical parameters: the maximum luminous flux and the illuminated area (i.e., light spot area). Both of these factors are contingent upon the properties of the phosphor materials used. The maximum luminous flux is determined by the phosphor material's luminous efficacy and its capacity to withstand the highest blue laser power density without reaching luminance saturation. This critical limit was defined as the luminance saturation threshold. On the other hand, the blue laser light incident upon the phosphor material tends to diffuse within the bulk, leading to an expansion of the light spot. This enlargement is generally detrimental to the emitted luminance of the light sources. In essence, there is an urgent need to engineer phosphor materials that both limit light spot expansion and boost the maximum luminous flux, thereby increasing the luminance of light sources.
Recently, Professor Rong-Jun Xie's group from Xiamen University has made a significant breakthrough: the fabrication of optical fiber-like core-cladding phosphor ceramics (CCPC), effectively addressing long-standing technical challenges and delivering ultra-high luminance performance.
The team prepared CCPC green bodies with different core diameters using the gel-casting technique. The green bodies were subsequently sintered at 2023 K for 5 hours in a vacuum environment maintained at 10⁻3 Pa. Finally, the interface between core and cladding of CCPC are tightly bonded and devoid of porosity at the interface.
The team published their work in Journal of Advanced Ceramics on July 21, 2025.
"The difference in refractive index between YAG:Ce and Al2O3, coupled with the non-luminescent properties of Al2O3, ensures that the light spot is mainly confined to the core region. This allows for precise control over the light spot area by adjusting the core dimensions" Shuxing Li, the co-corresponding author from Xiamen University. "Furthermore, the Al2O3
