Crystal growth and spectroscopic characterization of Yb-doped and Yb, Na-codoped PbF_2 laser crystals

摘要

High-quality pure PbF_2, Yb:PbF_2 and Yb, Na:PbF_2 crystals are grown by the Bridgman method in a nonvacuum atmosphere. Room-temperature absorption, photoluminescence spectra, and fluorescence lifetimes belonging to the transitions between ground state ~2F_(7/2) and the excited state ~2F_(5/2) of Yb~(3+) ions in these crystals have been investigated. The influence of codoping with Na~+ ions on the spectra has been studied. Experimental results show that codoping Na~+ ions in different Na:Yb ratios can modulate the spectroscopy and photoluminescence properties of Yb~(3+) ions in a PbF_2 lattice in a large scope: the Na~+ ions codoping with Yb~(3+) as charge compensators can suppress the deoxidization of Yb~(3+) to Yb~(2+), enhance the luminescence intensity and lengthen luminescence lifetime of Yb~(3+) ions.