Shift in preferred preparation conditions in MgO:Cr³⁺ phosphor-in-glass films for laser-driven high-radiance near-infrared emission

High-radiance near-infrared (NIR) phosphor-converted laser sources require converters with high efficiency, thermal robustness, and confined emission areas. Because converter performance is also affected by glass encapsulation, interfacial effects, optical transport, and thermal management, powder photoluminescence (PL) screening alone may not identify the preparation conditions preferred under high-power laser operation. Here, using MgO:Cr³⁺ phosphor-in-glass films (PiG-Fs) as a model system, we experimentally compare the preparation conditions favored by low-power powder PL screening with those providing the highest laser-driven output among the investigated PiG-F samples. The observed shift is accompanied by higher emission retention after glass encapsulation and improved high-power output at lower Cr³⁺ concentration. The F-0.004-1650°C PiG-F delivers >400 mW NIR radiant flux and 126 mW mm^-2 radiant exitance under 23.16 W laser excitation.