Crystal growth and spectroscopic characterization of Yb-doped and Yb, Na-codoped CaF2 laser crystals by TGT

High-quality 2 at%-doped Yb:CaF2 and Yb,Na:CaF2 single crystals with diameter of 76 mm were grown by the temperature gradient technique. For the first time, distribution coefficients (K0) of Yb in the two crystals were determined to be 1.07 and 0.91, respectively, by measuring the Yb concentrations at the growth starting position in the as-grown boules. Absorption and emission spectra of the two different crystals were measured at room temperature. Experimental results show that Na+ ions codoping with Yb3+ as charge compensators make Yb3+ ions in CaF2 lattice to be a quasi-single-center system, and greatly suppress the deoxidization of Yb3+ to Yb2+.