Optical spectroscopy of Yb3+ centers in BaMgF4 ferroelectric crystal

We report on the optical characterization of Yb3+ doped BaMgF4 nonlinear fluoride crystal grown by the Czochralski technique. Low temperature absorption spectroscopy reveals that Yb3+ incorporates into the matrix at four well differentiated centers. High resolution site selective experiments have been performed to determine the energy level schemes associated with the major Yb3+ centers detected in the system. The fluorescence decay times recorded at 10 K under selective excitation are analyzed for each Yb3+ center. The spectroscopic behavior of the codoped Yb3+:Na+:BaMgF4 system has been also investigated. Codoping with Na+ eliminates two Yb3+ centers present in the singly doped Yb3+:BaMgF4 crystal. The charge compensation mechanisms and site location for Yb3+ in the fluoride matrix are discussed.