Ca2YScAl2Si2O12:Cr3+ phosphor-in-glass film for laser-driven high-power near-infrared lighting

Abstract

The rise of laser diode (LD)-driven phosphor-converted near-infrared (NIR) lighting sources, offering unparalleled advantages in terms of brightness and imaging resolution, is hindered by a scarcity of color converters possessing desired properties. Herein, we synthesized a new Ca₂YScAl₂Si₂O₁₂:Cr³⁺ (CYSAS:Cr³⁺) broadband NIR-emissive garnet phosphor with a full width at half maximum (FWHM) of 165 nm, attributed to the presence of Cr³⁺ ions at two distinct crystallographic sites in CYSAS as verified through spectroscopic analyses. With the aid of a rapid infrared firing technique pioneered in our lab, a phosphor-in-glass film (PiGF) composite was then successfully sintered onto a sapphire plate (SP), showing minimal interfacial reactions during co-sintering and thus retention of luminescent properties. The saturation behavior of luminescence under intense blue laser irradiation was meticulously examined across different excitation modes. By incorporating a “phosphor wheel”, we achieved a peak NIR output power of 2626 mW (@17 W or 21.7 W mm⁻²), surpassing the majority of previously reported phosphor-converted lighting sources. The demonstration experiments highlighted the potential applications of the engineered laser-driven NIR light source in non-destructive detection, quantitative analysis of organic components, night vision and biological imaging.