A novel PiGF@ZS color converter with ZrO ₂ microsphere-embedded reflector for high-brightness laser lighting

Luminescence saturation of static color converters stands as a pivotal hurdle for the progression of next-generation high-brightness laser lighting. The conventional phosphor-in-glass film (PiGF) color converter faces inherent limitations in achieving high luminous efficacy (LE), constrained by insufficient phosphor excitation under focused laser irradiation and optical losses at the film-substrate boundary. Herein, a novel PiGF@sapphire converter with ZrO₂ microsphere-embedded reflector (PiGF@ZS) was proposed for laser lighting. This designed microstructure effectively reflects unabsorbed blue light back to the phosphor layer, significantly enhancing light utilization and LE for high-power laser lighting. Furthermore, the effects of laser spot diameters on the luminescence saturation were investigated in the PiGF@ZS converter. Benefiting from this synergistic opto-thermal design, the optimized PiGF@ZS converter exhibits a high LE of 240.5 lm/W and a maximum luminous flux (LF) of 3782 lm at 25 W laser (5 mm spot). Notably, under 3 W laser with a spot diameter of 1 mm, the PiGF@ZS converter achieves a LF 1.2 times that of conventional PiGF@S converter. Owing to the enlarged excitation area and improved heat dissipation, the PiGF@ZS converter achieves a lower surface temperature of 54.6℃ under 3 W with a 5 mm spot, compared to 61℃ for the PiGF@S converter, demonstrating enhanced thermal management capability. The microstructure ZrO₂ interface effectively mitigates thermal accumulation and enhances blue light utilization for PiGF based laser lighting.