Excitation scheme for the upper energy levels in a Tm:Yb:BaY2F8 laser crystal

Energy-transfer processes (including upconversion) are quantitatively studied in a Tm:Yb:BaY2F8 laser crystal. Several energy-transfer, cross-relaxation, and upconversion parameters are determined. We prove that at excitation of the crystal via Yb ions, the Tm levels F-3(4), H-3(4), F-3(3,2), (1)G(4), and P-3(0), are populated via Yb-Tm interaction, and the level D-1(2) is likely populated owing to F-3(3) Tm upconversion. The possibility of resonant excited-state absorption at 706 nm and resonant energy-transfer upconversion populating the level D-1(2) are discussed. The possibility of avalanche pumping of Tm:Yb:BaY2F8 at 706 nm is shown. (C) 1997 Optical Society of America.