Abstract:

3at%Yb:Ca_1-xR_xF_2+x (R=La, Gd; x=0, 0.01, 0.03, 0.06, 0.09) crystals were grown by a vertical Bridgman method. X-ray diffraction (XRD), Raman spectra, absorption spectra, fluorescence spectra and fluorescence lifetime were used to characterize the crystals. Effects of regulating ion La³⁺ and Gd³⁺ on lattice constants, Raman spectra and properties of Yb:CaF₂ crystals were investigated. Moreover, the relationship between structure and spectral property of Yb³⁺ ion was analyzed and discussed. The results show that lattice constant and Raman FWHM gradually increase with the increase of La³⁺ or Gd³⁺ ion doping concentration, demonstrat that lattice expands and lattice vibration modes increases, respectively. Among 3at%Yb:Ca_1-xLa_xF_2+x crystals, the crystal doped with 6at% La³⁺ has the largest absorption cross section (0.71×10^-20 cm²) and the largest fluorescence intensity. Moreover, the crystal doped with 3at% Gd³⁺ has the largest fluorescence intensity. Increasing Gd³⁺ content up to 6at%, the crystal has the largest absorption cross section (0.64×10^-20 cm²). These cooping crystals have better spectral parameters than 3at%Yb:CaF₂ crystals. Based on the above results, structure of Yb³⁺ ion may be changed and the crystalline spectral properties may be optimized partly through the regulation of La³⁺ or Gd³⁺ ions’ concentration.

Key words: Yb:CaF₂ crystal, regulating ion, structure, spectral property