Energy Levels of ${\mathrm{Dy}}^{2+}$ in the Cubic Hosts of Ca${\mathrm{F}}_2$, Sr${\mathrm{F}}_2$, and Ba${\mathrm{F}}_2$

The absorption and fluorescence spectrum of ${\mathrm{Dy}}^{2+}$ in the cubic hosts of Ca${\mathrm{F}}_2$, Sr${\mathrm{F}}_2$, and Ba${\mathrm{F}}_2$ was investigated. The crystal-field components of the ${}_{}{}^5{}_{}{}^{}\mathrm{I}_7^{}{}_{}{}^{}$ and ${}_{}{}^5{}_{}{}^{}\mathrm{I}_8^{}{}_{}{}^{}$ states were established and the cubic field parameters for the three hosts were deduced. The laser transition in the Ca${\mathrm{F}}_2$: ${\mathrm{Dy}}^{2+}$ system was identified and some of the laser characteristics were delineated. The $4f-4f$ transitions of ${\mathrm{Dy}}^{2+}$ were found to be of magnetic dipole origin. The nonradiative processes in the above systems are discussed.