Growth and optical properties of Yb~(3+) and Tb~(3+) codoped BaB_2O_4 crystals

摘要

Optical absorption and luminescence spectra of ytterbium and terbium codoped BaB_2O_4 (β-BBO and α-BBO) crystals grown in different conditions have been studied. Low-temperature absorption peaks were observed in all samples. Features related to rare earth ions were observed in absorption and luminescence spectra. Absorption and emission in the range 860-1000 nm are caused by ~2F_(5/2) <-> ~2F_(7/2) transitions in Yb~(3+) ions. Emission peaks at 500, 550, 590 and 630 nm correspond to ~5D_4 → ~7F_6, ~7F_5, ~7F_4, and ~7F_3 transitions of Tb~(3+) ions, respectively. The probable reasons of variations in spectroscopic features related to Yb in BBO host are discussed. It has been shown that the replacement of Ba~(2+) by Yb~(3+) in the lattice of BaB_2O_4 results in the decrease in the symmetry of oxygen surrounding of Yb~(3+).