Growth, structure, and spectroscopic properties of Yb,Ho,Pr:GYTO single crystal （Invited）

A new mid infrared laser material Yb,Ho,Pr:GYTO crystal was grown successfully using Czochralski method for the first time. The structural parameters were obtained by the X-ray Rietveld refinement method. The X-ray rocking curves of the (100), (010), and (001) diffraction face of Yb,Ho,Pr:GYTO crystal were measured. The full widths at half maximum of those diffraction peaks are 0.036°, 0.013°, and 0.077°, respectively, which indicates a high crystalline quality of the as-grown crystal. Laser Ablation Inductively-Coupled Plasma Mass Spectrometry was used to measure the concentrations of Yb³⁺, Ho³⁺, Pr³⁺, and Y³⁺ ions in the Yb,Ho,Pr:GdYTaO₄ crystal. The effective segregation coefficients of Yb³⁺, Ho³⁺, Pr³⁺, and Y³⁺ in Yb,Ho,Pr:GYTO crystal are 0.624, 1.220, 1.350, and 0.977, respectively. The room-temperature polarhosized absorption spectra of Yb,Ho,Pr:GdYTaO₄ was measured and the corresponding absorption transitions were assigned. The 2.9 μm fluorescence spectrum excited by 940 nm LD presents that the strongest emission is located at 2908 nm. In addition, the Yb-Ho-Pr energy transfer mechanism in GYTO was also demonstrated. Compared with Ho:GYTO crystal, the lifetime of ⁵I₇ level of Yb,Ho,Pr:GYTO crystal is reduced by 87.13%, which is close to that of the upper level ⁵I₆, indicating that Yb,Ho,Pr:GYTO crystal is easier to realize population inversion and laser output.