Micro-defects and luminescence of thulium-doped yttrium aluminum garnet single crystals

Thulium-doped yttrium aluminum garnet (YAG) single crystals with composition (Tm x Y (1- x ) ) 3 Al 5 O 12 (x = 0.001–0.02) were prepared by the optical floating zone method. The crystals were of high quality with no cracks, bubbles, or inclusions, and with >80% visible light transmittance . The lowest value for the mean positron lifetime was observed with crystals which had x = 0.01, which demonstrates that this composition had the fewest number of defects. This sample also produced the highest emission intensities in the PL spectra, and had narrower lines than those previously reported for Tm 3+ -doped yttria-stabilized zirconia. However, with higher Tm 3+ concentrations, interactions between neighboring Tm 3+ ions resulted in partial quenching of the luminescence. Overall, Tm-doped YAG single crystals synthesized by the optical floating zone (OFZ) method contained few defect centers and exhibited narrow luminescence linewidths , which demonstrate potential uses in high resolution applications.