Optical amplification and photodynamic processes in $\mathrm{CaF}_2$ and $\mathrm{KY}_3\mathrm F_{10}$ crystals doped with trivalent cerium and ytterbium

UV-pump-induced photodynamic processes investigation in $\mathrm{CaF}_2$ and $\mathrm{KY}_3\mathrm F_{10}$ crystals doped with $\mathrm{Ce}^{3+}$ and $\mathrm{Yb}^{3+}$ is reported. Excited-state absorption cross section values for $\mathrm{Ce}^{3+}$ ions and recombination transition rates of free carriers in those crystals have been evaluated. For the first time optical amplification in $\mathrm{CaF}_2:\mathrm{Ce}^{3+}+\mathrm{Yb}^{3+}$ crystal has been observed. Its spectral characteristics are reported.