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. Y 3 Al 5 O 12 :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 Al 2 O 3 -YAG:Ce and Al 2 O 3 -(Gd,Y)AG:Ce transparent ceramics were fabricated by vacuum sintering, and their microstructure, thermal and optical properties were controlled by changing the Ce 3+ or Al 2 O 3 content as well the thickness of the ceramics. Both Al 2 O 3 -Y 2.925 Al 5 O 12 :Ce 0.0175 (AY0.0175) and Al 2 O 3 -(Gd 0.1 Y 2.89 )Al 5 O 12 :Ce 0.01 (AGY) ceramics containing 70% (in mass) Al 2 O 3 show a luminance saturation threshold of 30.3 W/mm 2 and 38.4 W/mm 2 , 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.