Optical path coupling regulation of excitation light and LuAG: Ce phosphor ceramics for high-luminous-efficiency laser lighting

Abstract

In the preparation processes of laser lighting sources, although optimizing phosphor materials remains the primary strategy to enhance phosphor conversion efficiency, the excitation modes applied to these materials have emerged as an equally effective means. In this study, the luminescence performance of a remote LD-based light source was effectively regulated by controlling the exciting distance and exciting angle between phosphor ceramics and blue LD. Under optimized conditions with an exciting distance of 200 mm and an angle of 60°, a maximum LF of 27,124 lm was achieved, corresponding to a calculated LER of 219.6 lm W⁻¹. Oblique incidence excitation of phosphor ceramics was found to exhibit significantly enhanced luminescence performance relative to conventional vertical incidence. The operating temperature of the ceramics decreased gradually with increasing exciting angles, primarily due to decreased power density caused by spot size expansion. These findings reveal that tailoring excitation geometry can effectively balance thermal management and optical efficiency in phosphor ceramics-based remote LD systems, offering critical insights for the design of high-power transmission-type packaging devices.