Laminated structural Al2O3/YAG:Ce composite ceramic phosphor with high front light emission for transmissive laser lighting

Abstract

The realization of high front light emission in laser lighting under transmissive modes is heavily constrained by low thermal stability and light extraction efficiency of color converter materials. Therefore, it is necessary to improve the heat dissipation capacity and light utilization efficiency of the color converter through appropriate microstructural adjustments. In this study, what we believe to be a novel laminated structure consisting of Al2O3 and YAG:Ce was designed and fabricated for transmissive laser lighting. Through this design, it was possible to change the phosphor emission angle, overcoming the limitations of total internal reflection and enabling maximal emission of yellow phosphor from the ceramic surface. This laminated structure enhanced the front light emission efficiency by 24.4% compared to composite ceramic phosphor. In addition, the thermal conduction area between the phosphor layer and the heat dissipation layer have been effectively enhanced. Ultimately, under a high-power density of 47.6 W/mm2, all ceramics showed no luminous saturation threshold. A high-brightness front light with a luminous flux of 651 lm, a luminous efficiency of 144 lm/W, a correlated color temperature of 6419 K and the operating temperature as low as 84.9 °C was obtained. These results suggest that laminated structural Al2O3/YAG:Ce composite ceramic is a promising candidate for transmissive mode laser lighting.