Enhanced anti-Stokes emission in oxyfluoride glass ceramics for optical refrigeration

Rare earth doped oxyfluoride glass-ceramics (GCs) have recently attracted much attention as a novel material candidate for solid state laser cooling application. In this study, highly transparent (~ 90 % in the infrared region) ytterbium doped aluminosilicate oxyfluoride glasses and glass ceramics containing YF3 nanocrystals prepared by the conventional melt quenching process have been investigated to determine and compare their potential to obtain high photoluminescence quantum yield (PLQY). The highest ASF emission intensity was observed in the GC composition with near-infrared PL emission centered at ~1010 nm under a laser excitation at 1020 nm. The PL spectra at different temperatures (25 °C – 200 °C) were measured using different excitation wavelengths varying from 920 nm to 1030 nm in order to understand the nature of Stokes and anti-Stokes emission in glass ceramics. The glass-ceramic has a net heating near to zero with an excitation between 1020 nm and 1030 nm showing its potential for optically induced heat-management applications. The optical properties such as refractive index, quantum efficiency and lifetime of GC and the precursor glass were also studied in detail in order to explore these properties for laser cooling applications.