Dual function optically coated sapphire substrate YAGG:Ce color converters for high brightness laser-driven solid-state lighting

Abstract

This study innovatively proposes an optically coated sapphire-based composite structure, in which a multi-functional anti-reflection/high-reflection (AR/HR) optical coating is constructed to achieve breakthrough performance in photothermal management for high-power laser lighting. The designed AR/HR coating maintains a high blue light transmittance of 94.5%, while suppressing fluorescence-band stray light by 98.82% and significantly increasing fluorescence reflectivity to 80% (compared to 15% before coating). We further developed a coated sapphire-based phosphor-in-glass film (CS-PiF). Under 450 nm blue laser excitation, this structure demonstrates an ultra-high luminous flux of 1582.7 lm, which is 1.9 times that of conventional uncoated phosphor-in-glass films (PiF), along with a peak luminous efficacy of 239 lm W⁻¹ and a thermal conductivity improved to 16.9 W m⁻¹ K⁻¹. In laser lighting application tests, the CS-PiF achieved an illuminance of 39 580 lux at a 2-meter distance, outperforming the conventional solution by a factor of 1.9. This technology breaks through the light extraction limitations of traditional phosphor converters and provides a novel solution for high-brightness solid-state laser lighting.