Sc3+ doping enhances the wide-spectrum emission of Tm3+/Yb3+ co-doped Y3ScAl4O12 crystals

High-quality Tm 3+ and Yb 3+ co-doped YAG and YSAG crystals were successfully synthesized by the optical floating zone technique. This work systematically examines the relationship between structural attributes and optical performance in the crystals. This work mainly focuses on the effect of Sc 3+ doping on luminescent behavior. The doping of Sc 3+ ions results in variations in the crystal field, which in turn alter the luminescent properties. The powder X-ray diffraction confirms that the prepared samples all possess a cubic garnet structure and high crystallinity at room temperature. Both upconversion and downconversion photoluminescence measurements were performed under 980 nm excitation. The photoluminescence test results show that the upconversion luminescence intensity of the YSAG crystal is enhanced in the visible light region, and the downconversion infrared emission near 1800 nm exhibits spectral broadening. Raman spectroscopy indicates that the alteration of the photoluminescence properties of the crystal stems from the reduced maximum phonon energy, and the increase in the local structural disorder of the crystal. Furthermore, the influence of lattice structure alteration is also reflected in the significantly prolonged fluorescence lifetime of crystal samples, indicating the role of Sc 3+ doping in suppressing non-radiative relaxation. This study indicates that the doping of Sc 3+ enhances the visible emission intensity, infrared spectral bandwidth and the excited-state lifetime. The YSAG formed by doping is a matrix material with promising development prospects in the application of lasers and optical devices.