Heat Dissipation Enhancement of Phosphor-Converted White Laser Diodes by Thermally Self-Managing Phosphor-in-Glass

Abstract

Laser-driven white lighting has been considered as a next-generation high-brightness white lighting source. Thermally stable color converter is an essential down-conversion material for phosphor-converted white laser diodes (pc-wLDs), which inevitably endures high-density laser excitation and huge heat shock from conversion loss. In this work, we proposed a thermally self-managing phosphor-in-glass (PiG) converter to enhance the heat dissipation of reflective pc-wLDs. The PiG converter was prepared by printing and sintering a phosphor glass film on the cold side of thermoelectric cooler (TEC). By controlling the input current of TEC, the heat generated from phosphors under high-power laser excitation was effectively and initiatively dissipated into the ambient environment due to the Peltier effect of TE materials. As the laser power (LP) increases from 0.73 to 5.6 W, the working temperature of PiG film slowly increases from 2.3°C to 6.1°C. The maximum temperature of PiG film is reduced by 61.1 °(~91%) at the LP of 5.6 W. Furthermore, the PiG-TEC-based pc-wLD achieves a cool white light and stable light quality under various LPs. At the LP of 4.5 W, the correlated color temperature (CCT) of pc-wLD is 6449 K, and the chromaticity coordinate of pc-wLD is (0.3139, 0.3274). The results indicate that the proposed PiG-TEC converter enhances the thermal performance of high-brightness laser-driven white lighting.