Innovative Architecture for Phosphor‐in‐Glass Films Enabling Superior Luminance and Color Quality Laser‐Driven White Light

Abstract Laser‐driven white light exhibits exceptional brightness and directionality, making it particularly well‐suited for spotlight applications. Yet, attaining high‐quality white light remains challenging due to the sluggish heat dispersion and inconsistent light uniformity of color converters. In this study, an innovative phosphor‐in‐glass (PiG) film architecture is introduced, aiming to achieve superior quality laser‐driven light, where the traditional Y 3 (Ga,Al) 5 O 12 :Ce 3+ (YAGG:Ce 3+ ) PiG film is topped with a Al 2 O 3 ‐in‐glass (AiG) film. The heightened thermal conductivity of the AiG film facilitates quicker dissipation of heat, consequently elevating the luminescence saturation threshold from 14 to 16 W mm −2 and luminous flux from 1243.8 to 1475.9 lm. The increased light scattering attributed to the AiG film also effectively disperses both laser and emitted light, significantly enhancing the angular consistency of color rendering index (Ra). This improvement is evident as the coefficient of variation (C v ) decreases dramatically from 16.69% to 0.25%. Moreover, by integrating CaAlSiN 3 :Eu 2+ (CASN:Eu 2+ ) into the PiG film and fine‐tuning the YAGG:Ce 3+ and CASN:Eu 2+ ratio, a high‐quality laser‐driven white light achieving an impressive color rendering index (Ra) of 88.7 and offering an adjustable correlated color temperature (CCT) has been developed. This innovation holds tremendous potential as a versatile spotlight solution for both indoor and outdoor settings.