Surface texture induced light extraction of novel Ce:YAG ceramic tubes for outdoor lighting

Ce:YAG transparent ceramics for white LEDs devices suffered from the issues of low light extraction, narrow luminous angle and poor thermal performance. In this paper, the different textures were grown on the surface of Ce:YAG transparent ceramics by a simple mechanical grinding to enhance the light extraction, and the luminous angle of 4 was realized by the novel design of hexahedral ceramic tubes excited by the columnar blue LED chip arrays with the high efficiency column-wing radiator. More converted yellow photons were allowed to transmit through the ceramic surface owning to the texture-induced reduction in total internal refection effect. The light extraction and blue-to-yellow conversion were significantly enhanced by controlling the thickness and smoothness of ceramics surface rather than polishing. The as-fabricated ceramic tubes with a thickness of 1.0mm and ground by abrasive materials with particle size of 20m exhibited the highest luminous efficiency of similar to 85.57lm/W, the low correlated color temperature of 4358K and the stable optical performance under various driven currents. A simple, high efficiency and low cost approach was proposed in this study to improve the luminous performance of high-power photo-conversion devices for outdoor lighting.