Interface Reaction Inhibition in Phosphor-in-Silica Glass for High-Performance Laser Illumination

• • Cs2O incorporation preserves 97.7% of pure YAG:Ce IQE, with absolute IQE of 88.3% after 1400°C/2h calcination, demonstrating exceptional thermal stability for high-power laser applications. • • Mixed alkali effect (10% Li2O + 5% Cs2O) enables PiSG to withstand hydrothermal treatment at 200°C for 10 h, addressing humidity-related degradation in practical devices. • • Optimized PiSG film on sapphire achieves 3080.09 lm luminous flux and 213.43 lm W−1 efficiency under blue laser excitation, outperforming conventional silicone-encapsulated phosphors in thermal management. • • High SiO2 content (>85 wt%) combined with Cs2CO3 flux promotes dense glass formation, suppressing interface reactions and maintaining structural integrity at sintering temperatures >1200°C.