Growth, structure and spectral characteristics of KEr0.1Yb0.9(WO4)2 laser crystal

The 10 at.% Er3+-doped KYb(WO4)2 (KEr0.1Yb0.9(WO4)2) laser crystal with dimensions up to 25 mm × 15 mm × 10 mm was grown by the Kyropoulos method. The crystal structure was identified as β-KEr0.1Yb0.9(WO4)2 by XRD analysis. Through TG-DTA curves, the melting point and transition point of the crystal were determined to be 1058 and 1031 °C, respectively. Infrared spectrum and Raman spectrum were measured, and the vibration frequencies of infrared and Raman active modes for the crystal were assigned. The absorption cross section is 3.1 × 10−20 cm2 at chief peak of 981 nm with the absorption line width of 26 nm. Based on the Judd-Ofelt theory, the intensity parameters Ωλ (λ=2,4,6) calculated were: Ω2=16.34 × 10−20 cm2, Ω4=4.18 × 10−20 cm2, and Ω6=1.26 × 10−20 cm2. There was a strong emission peak near 1533 nm and the emission line width at the main peak at 1533 nm run up to 55 nm with the emission cross section of 3.47 × 10−20 cm2. These optical parameters indicated the potential of this crystal used as an excellent laser material for 1540 nm nearby human-eye safe.