Dichromatic fluorescent splicing color wheel: Enabling high-quality laser lighting on high thermal conductivity AlN substrate

Abstract

In recent years, the development of solid-state lighting devices has increasingly shifted towards high-power laser illumination, making it imperative to develop fluorescent conversion materials with exceptional thermal stability and luminous quality. In this study, we introduced a highly reflective TiO₂ substrate in combination with a high thermal conductivity AlN substrate to design a Ce:YAG-PiG-TiO₂-AlN Film (Ce:YAG PTAF) color converter with outstanding photothermal performance. Remarkably, the thermal conductivity of this material reaches 48.28 W m⁻¹ K⁻¹. Notably, the optimized PTAF can withstand a high-power output of up to 12.14 W in a static environment, with a maximum luminous flux (LF_max) of 2284.6 lm and maximum luminous efficacy (LE_max) of 222.35 lm W⁻¹, showcasing its excellent optical properties. Furthermore, the fabricated Ce:YAG-PiG-TiO₂-AlN-Wheel (Ce:YAG PTAW), equipped with a motor operating at 7200 r/min, emits an extraordinary brightness of 4404 lm under 88 W of ultra-high laser irradiation, with stability surpassing that of commercial silicone color wheels, thanks to its superior Li₂O-Al₂O₃-SiO₂ (LAS) glass system. Interestingly, we designed an innovative spatially separated two-color segmented wheel structure, effectively mitigating the photon reabsorption phenomenon caused by the overlap of the fluorescent powder absorption peaks. When the ratio of Ce:YAG to Ce:GdYAG is 240:120, it yields white light with a color rendering index (CRI) of 80.2, and luminous flux remaining at 3317.8 lm. When encapsulated in a reflective module, it accurately reflects the true color states of objects. These results collectively indicate that both Ce:YAG PTAF and PTAW possess significant application potential in the realm of high-power laser illumination.