Growth and spectral properties of Pr,Yb,Ho:GdScO₃ crystals

Abstract

In order to explore and develop new crystal materials in the 2.7~3 μm band, Pr,Yb,Ho:GdScO₃ crystal were successfully grown by the Czochralski method for the first time. X-ray diffraction measurement was performed to obtain powder diffraction data. Raman spectra were measured and the vibration peaks were identified. The transmission spectrum, emission spectrum and fluorescence lifetime of Pr,Yb,Ho:GdScO₃ crystal were also characterized. The center of the strongest absorption band is at 966 nm with the half-peak width 90 nm, which comes from the transition of Yb³⁺: ²F_7/2→²F_5/2. The absorption cross section of Yb³⁺ were calculated and the values at 966、973、985 nm are 0.62×10^-20, 0.60×10^-20 and 0.58×10^-20 cm²respectively. The maximum emission peak is at 2850 nm and the half-peak width is 70 nm, the lifetimes of Ho³⁺:⁵I₆ and ⁵I₇ were measured to be 1094 μs and 56 μs respectively, and the emission cross section at 2850 and 2935 nm were calculated to be 3.6×10^-20cm² and 1.21×10^-20 cm². Compared with Yb,Ho:GdScO₃ crystal, the absorption peak of Yb³⁺ and the emission peak were both broadened, which are related to the increase of crystal disorder. The lifetime of the lower energy level decreases significantly. Furthermore, the energy transfer mechanism between Ho³⁺ and Pr³⁺ was analyzed, and the energy transfer efficiency between Ho³⁺:⁵I₇ and Pr³⁺:³F₂+³H₆ was calculated to be 99%, which is higher than that in other materials. All the results show that Pr,Yb,Ho:GdScO₃ crystal is an excellent 2.7~3 μm laser material, and is easier to achieve laser output than Yb,Ho:GdScO₃ crystal.