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A new promising 2.9 μm Tm,Ho:GdYTaO4 (Tm,Ho:GYTO) laser crystal was grown by the Czochralski method. The full width at half maximum (FWHM) of X-ray rocking curve on the (0 1 0) face is only 0.05°, which indicates that the crystal has high crystalline quality. The structure parameters of Tm,Ho:GYTO crystal were determined by Rietveld refinement method. Chemical etching is employed to investigate the defect structure of Tm,Ho:GYTO crystal with KOH etchant. The absorption, emission spectra, and level lifetimes were measured, and the corresponding absorption transitions were assigned. The absorption cross-section at 790 nm was calculated to be 2.04 × 10−20 cm2 and maximum emission-cross section at 2932 nm was 2.05 × 10−20 cm2. The level lifetimes of 5I6 and 5I7 are 131 μs and 4.09 ms, respectively. Compared with other hosts, such as Ho:YAG, the shorter lifetime of 5I7 and long lifetime of 5I6 in the Tm,Ho:GYTO crystal are easier to realize population inversion. The Tm–Ho energy transfer mechanism in GYTO is also demonstrated.

A new crystal of Yb-doped gadolinium niobate, 5 at.% Yb:GdNbO 4 , is grown by Czochralski method for the first time. The structure of Yb:GdNbO 4 is determined by Rietveld refinement to the X-ray powder diffraction data and it belongs to the monoclinic space group of I 2/a . With the center of 955 nm, the FWHM of absorption spectra is 57 nm and the absorption cross section is calculated to be 0.97 × 10 −20 cm 2 . Spectral parameters are calculated with absorption spectrum. In emission spectra, the strongest peak is at 1001 nm and the FWHM is 49 nm. In comparison with corresponding emission cross section of Yb:YSO and Yb:GSO, Yb:GdNbO 4 exhibits a relatively larger emission cross section. In addition, a maximal output power of 270 mW is obtained and the slope efficiency is 7.5%.

Large size high transparent TSAG and TSLAG single crystals of O 65 mm × 70 mm have been grown successfully by the Cz method. The refractive indices at 473, 532, 632.8 and 1064 nm are 1.9214 - 1.8817 for TSAG and 1.9242 - 1.8841 for TSLAG. Their Sellmeier equations are fitted. The average thermal expansion coefficients of TSAG and TSLAG at 300 – 373 K, 300 – 473 K, 300 – 573 K, 300 – 673 K, and 300 – 773 K are measured. The values of thermal expansion coefficients of TSAG and TLSAG crystals coincide within the measurement error (differ by 0.3–0.4%). The thermal diffusivity values of TSAG and TSLAG are 1.454 and 1.418 mm2 s−1 at 300 K, respectively. Calculated with the specific heat results, the values of thermal conductivity of TSAG and TSLAG are 4.45 and 4.20 W (m K)−1 at 300 K. Moreover, the Verdet constants of TSAG are 218, 152, and 65 rad/m/T at 532, 633, and 1064 nm, while those of TSLAG are 246, 146, and 56 rad/m/T, respectively. In further, the relationships between Verdet constant and wavelength of TSAG and TSLAG are obtained.