Novel high-thermal-conductivity composite ceramic phosphors for high-brightness laser-driven lighting

Abstract

The widespread application of laser diodes (LDs) in high-brightness lighting is limited by the insufficient heat dissipation of colour converters due to high-power laser irradiation. In this study, a novel MgO–YAG:Ce composite ceramic with excellent optical and thermal properties was fabricated by hot pressing. The thermal conductivity of the MgO–YAG:Ce composite ceramic is 14–21% higher than that of the Al₂O₃–YAG:Ce composite ceramic in the temperature range of 25–200 °C. When pumped by blue LDs with 1 W mm⁻², the MgO–40 vol% YAG:Ce composite ceramic produces white light with a luminous efficacy of 292 lm W⁻¹. Moreover, it exhibits a luminous saturation threshold of as high as 32.2 W mm⁻² and a maximal luminous flux of 3979 lm. These results indicate that MgO–YAG:Ce composite ceramic is a promising phosphor converter for high-power laser-driven lighting.