EFFICIENT 2 MU-M STIMULATED-EMISSION IN THE F-4(9 2)-]I-4(11/2) CHANNEL FROM MONOCLINIC BAYB2F8-ER3+ CRYSTALS/

New spectroscopic and laser data on monoclinic Ba(Yb1-xErx)(2)F-8 crys tals are obtained. Efficient 2 mu m stimulated emission of Er3+ ions i n the F-4(9/2)-->I-4(13/2) channel and 2 and 3 mu m cascade lasing of the sequential F-4(9/2)-->I-4(11/2)-->I-4(13/2) transitions were excit ed at room temperature under Xe flashlamp pumping. Intensity character istics of manifold-to-manifold (JJ' transitions) such as Einstein coef ficients A(JJ'), line strengths s(JJ'), branching ratios B-JJ', and ra diative lifetimes tau rad for the initial lasers states I-4(13/2), I-4 (11/2), I-4(9/2), F-4(9/2), S-4(3/2), and H-2(2)(9/2) were analyzed in detail. All observed laser transitions between individual Stark level s were identified. Unlike well-know 2 mu m lasers with Ho3+, Tm3+, Co2 +, and Ni2+ ions in many oxide and fluoride compounds, BaYb2F8:Er3+ cr ystals operate on a pure four-level generating scheme.