Superstoichiometric Spinel Phosphor-in-Glass Films for Laser-Driven Ultrabroadband Near-Infrared Light Sources
Laser-driven broadband near-infrared (NIR) light sources are highly desirable for diverse non-visible optical applications. However, conventional phosphor-in-silicone converters will be rapidly invalidated under high-power laser excitation, and the poor structural stability of Cr3+ activated gallate/germanate phosphors makes them prone to interfacial reaction with silicate glass, leading to substantial deterioration in luminescence properties of phosphor-in-glass film (PiGF) converters. Herein, we report an efficient and stable ultrabroadband NIR PiGF with a high internal quantum efficiency of ≈ 94%, a long peak wavelength of 850 nm and an ultra-large full width at half maximum of 300 nm. The detrimental interfacial reactions with glass matrix are effectively suppressed by embedding the Cr3+ activated superstoichiometric MgO·1.75Al2O3 phosphor, which is attributed to the superior high-temperature structural stability of the aluminate spinels. Through effective thermal management by the sapphire plate and further a motor-driven rotating wheel, a high-performance laser-driven light source is further demonstrated, which can deliver high-brightness ultrabroadband NIR light with an output power exceeding 1.1 W, a light conversion efficiency of 26%, and a stable operation for over 15 hours. Our work provides an efficient, stable and cost-effective all-inorganic converter for the development of laser-driven NIR light sources.