Investigation and Enhancement of Spatial Light Uniformity of Laser-Driven PiGF for High-Brightness Lighting

Phosphor-converted laser lighting is a new generation of high-brightness solid-state light source, and its spatial light uniformity is of crucial importance for actual applications. Herein, the spatial light distribution of a laser-driven phosphor-in-glass film (PiGF) with a transmissive type was systematically studied for the first time, and its spatial light uniformity was enhanced by integrating an aluminum reflective cup. The YAG:Ce PiGFs with various thicknesses were printed and sintered on sapphire substrates. The PiGF was tightly bonded on the sapphire and maintains a high quantum yield (QY) of 91.9%. With the increase in PiGF thickness, the luminous flux of laser-driven PiGFs initially increases and then decreases, while the correlated color temperature (CCT) gradually decreases. The spatial irradiance and CCT of common laser-driven PiGFs show a strong central peak and rapid radial attenuation. By integrating the aluminum reflective cup, the laser-driven PiGFs emit white laser light with uniform irradiance. The related CCT increases from 6164 K at 0° to 9493 K at 25°, corresponding to a balanced warm-to-cold white emission. The work provides valuable guidance for testing and optimizing of spatial light distribution in high-brightness laser-driven lighting.