Spectroscopy investigation of highly doped LiCaAlF6:Ce3+ crystals

Crystals of the UV lasers active media $\mathrm{Ce}^{3+}: \mathrm{LiCaAlF}_{6}$, which are characterized by the formation of several types of $\mathrm{Ce}^{3+}$ ion centers, have been studied. Presence of nonequivalent impurity centers was confirmed by detection of zero-phonon lines for two centers in low-temperature luminescence spectra, as well as from EPR spectra for various magnetic field orientations relative to the crystallographic axes of the samples. We have shown that for $\mathrm{Ce}^{3+}: \mathrm{LiCaAlF}_{6}$ crystals, with an increase in the concentration of $\mathrm{Ce}^{3+}$ ions in the melt, crystallization occurs in such a way that the concentration of impurity centers of lower symmetry increases to a greater extent than centers of higher symmetry. Moreover, laser oscillation belongs to precisely this type of center.