Growth and optical properties of Yb3+ and Tb3+ codoped BaB2O4 crystals

Optical absorption and luminescence spectra of ytterbium and terbium codoped BaB2O4 (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 2F5/2↔2F7/2 transitions in Yb3+ ions. Emission peaks at 500, 550, 590 and 630 nm correspond to 5D4→7F6, 7F5, 7F4, and 7F3 transitions of Tb3+ 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 Ва2+ by Yb3+ in the lattice of ВаВ2О4 results in the decrease in the symmetry of oxygen surrounding of Yb3+.