Strong thermal stability of Lu3Al5O12:Ce3+ single crystal phosphor for laser lighting

Abstract

Green-yellow single crystal Lu3Al5O12:Ce3+ (LuAG:Ce) as a color conversion phosphor for high-power laser lighting was grown through a floating zone method by an image furnace. It showed an excellent thermal stability, a lower quantum efficiency (QE), and a broader photoluminescence excitation (PLE) spectrum compared with the polycrystalline powder phosphor. The thermal stability was explained by a decrease of intrinsic defects and a less phonon generation at high temperature, confirmed by PLE spectra and temperature-dependent Raman spectra, respectively. To evaluate its feasibility for high-power laser lighting, the single crystal LuAG:Ce was applied to a 5W blue laser diode with a remote-phosphor structure, and thus it reached a lower equilibrium temperature at 62°C after 40min operating in comparison with the polycrystalline powder phosphor (95°C). Thus, the single crystal LuAG:Ce phosphor can achieve the extremely stable light emission without an efficiency loss under the high-power density of blue laser diode.