Investigation of the optical properties of the Na$_4$Y$_6$F$_{22}$ crystal doped with Ce$^{3+}$ and Yb$^{3+}$ ions under intense laser pumping

This paper reports on the results of investigations into the optical properties of the Na$_4$Y$_6$F$_{22}$ : Ce$^{3+}$, Yb$^{3+}$ crystal. The technique for growing and preparing samples is briefly outlined. The instruments used for performing spectroscopic investigations and studying optical properties of samples under intense laser pumping are described. The results of the investigations performed are presented and discussed.