High Performance Phosphor‐in‐Glass Film on Grating Structure Sapphire Substrate for Laser Lighting

ABSTRACT Laser lighting has the advantages of ultra‐high brightness and luminous efficiency in the field of solid‐state lighting. As one of the luminescence color converters for white laser lighting, phosphor‐in‐glass film (PiF) based on sapphire substrate is attracting much attention. In this work, a grating structure sapphire substrate (GS) with convex cross‐section was fabricated. PiFs, consisting of melted silicon borate glass matrix and Y 3 Al 5 O 12 :Ce 3+ phosphor powder, were prepared either on the same side (PiF‐GS‐S) or the opposite side (PiF‐GS‐O) of GS. Compared with PiF on planar sapphire (PiF‐F), the incident blue laser beam is modulated by the pattern on the GS, which refracts the light and causes divergence of the laser beams. This expands the laser spot on the PiF, improving the uniformity of the laser beams. The saturation luminous flux of the PiF‐GS‐O under the 14.48 W/mm 2 laser excitation (1446 lm) is 49.7% higher and has a lower maximum temperature than those of the PiF‐F, while maintaining a high luminous efficiency (150 lm/W). In addition, the effects of the two sintering methods on laser refracting are comparatively analyzed. The results demonstrate that the laser spot can be enlarged and homogenized by patterning the sapphire substrate, which finally helps to achieve higher luminous flux, higher luminous efficiency, and higher saturation threshold for laser lighting.