Impact of Ce3+ concentration and thickness on luminance and chromaticity uniformity of YAG:Ce ceramic color converters for laser lighting

Free from the “curse” of efficiency droop in high-power LEDs, laser-driven phosphor-converted laser diodes (pc-LDs) light sources demonstrate significantly greater potential in achieving ultra-high brightness white light. To mitigate the luminance saturation, rigorous re-optimization of luminescent ion concentration and heat dissipation geometry is essential. Beyond the photometric and colorimetric properties, the low spatial uniformity of pc-LDs poses a critical but often overlooked challenge. Here, we present a systematic investigation of the effect of Ce³⁺ concentration and thickness on the luminance and uniformity of YAG:Ce ceramic color converters. To quantitatively assess luminescence uniformity, high dynamic range color images were captured to statistically evaluate spatial chromaticity variations across the luminescent spot. The results firmly demonstrated that the Ce³⁺ concentration and thickness are two interdependent parameters closely related to uniform chromaticity and luminance, which should be optimized simultaneously. This study provides critical optimization guidelines for laser lighting development.