Laser-driven composite ceramic enabling superhigh-luminance white light

Laser-remote activated phosphor (LARP) converted solid state lighting is now developing towards high power density and super-brightness, and phosphor ceramic converters with high efficiency, high thermal conductivity, acceptable transmittance and suitable spectra are thus required. Y3Al5O12:Ce (YAG:Ce)based ceramics are promising color converters to produce white light with a color temperature of 6000 K for vehicle headlamps, but the brightness and luminous efficiency are not well optimized. In this work, two series of Al2O3-YAG:Ce and Al2O3-(Gd,Y)AG:Ce transparent ceramics were fabricated by vacuum sintering, and their microstructure, thermal and optical properties were controlled by changing the Ce3+ or Al2O3 content as well the thickness of the ceramics. Both Al2O3-Y2.925Al5O12:Ce0.0175 (AY0.0175) and Al2O3-(Gd0.1Y2.89)Al5O12:Ce0.01 (AGY) ceramics containing 70% (in mass) Al2O3 show a luminance saturation threshold of 30.3 W/mm2 and 38.4 W/mm2, enabling to produce white light with a color temperature of 6000 K, luminous flux of 1928 lm and 3101 lm, luminous efficiency of 135.0 lm/W and 161.1 lm/W when pumped by blue laser diodes, respectively. This work provides a solution to finely control the composition, microstructure, and optical properties of transparent ceramics for super-high brightness laser-driven solid-state lighting. (c) 2025 The Authors. Published by Elsevier B.V. on behalf of The Chinese Ceramic Society. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).