High-Quality White Laser Diode Fabricated by Laser-Driven Tricolor PiG Film-on-Sapphire

Phosphor-converted white laser diode (WLD) is considered as a promising light source in next-generation high-brightness lighting. However, the WLD suffers from low optical quality in luminous efficacy and color rendering. In this work, we fabricated a high-quality WLD by a blue laser-driven a tricolor phosphor-in-glass (PiG) film-on-sapphire (PIGS). The tricolor PiGS was prepared by sintering a green/yellow/red phosphor glass film on a sapphire substrate. The optical quality of tricolor PiGS-WLDs were optimized by adjusting the phosphor ratio. At the phosphor ratio of 9:6:1, the PiGS-WLD achieves high optical quality with a luminous flux of 362.1 lm, a color rendering index (CRI) of 80.3, and a correlated color temperature (CCT) of 4590 K at a laser power of 2.4 W. The PiGS-WLD has the highest luminous efficacy of 154.5 lm/W at 3.15 W. Furthermore, the PiGS-WLD displays excellent color stability with small CCT and CRI deviation under various laser powers and continuous excitation. The surface temperature of PiGS-WLD is stable at 104 °C due to the high thermal conductivity of sapphire substrate. Therefore, this study provides a stable and high-quality laser-driven white light source for high-brightness lighting and display.