Energy level decay and excited state absorption processes in erbium-doped tellurite glass

Gomes, L.Oermann, M.Ebendorff-Heidepriem, H.Ottaway, D.Monro, T.Librantz, A.Jackson, S.2011-12-132011-12-132011Journal of Applied Physics, 2011; 110(8):083111-1-083111-100021-89791089-7550http://hdl.handle.net/2440/68773The fundamental excited state decay processes relating to the 4I11/2 → 4I13/2 transition in singly Er3+-doped tellurite (TZNL) glass have been investigated in detail using time-resolved fluorescence spectroscopy. Selective laser excitation of the 4I11/2 energy level at 970 nm and selective laser excitation of the 4I13/2 energy level at 1485 nm has established that energy transfer upconversion by way of a dipole-dipole interaction between two excited erbium ions in the 4I13/2 level populates the 4I11/2 upper laser level of the 3 μm transition. This upconversion has been analyzed for Er2O3 concentrations between 0.5 mol. % and 2.2 mol. %. The 4I13/2 and 4I11/2 energy levels emit luminescence with peaks located at 1532 nm and 2734 nm, respectively, with radiative decay efficiencies of 65% and 6.8% for the higher (2.2 mol. %) concentration sample. The low 2.7 μm emission efficiency is due to the non-radiative decay bridging the 4I11/2 → 4I13/2 transition and energy transfer to the OH− groups in the glass. Excited state absorption was observed to occur from the 4I13/2 and 4I11/2 levels with peak absorptions occurring at 1550 nm and 971 nm, respectively. The decay time of the 4I11/2 excited state decreased with an increase in the Er3+ concentration, which related to energy transfer to OH− ions that had a measured concentration of 6.6 × 1018 cm−3. Results from numerical simulations showed that a population inversion is reached at a threshold pumping intensity of ∼80 kW cm−2 for a cw laser pump at 976 nm if [Er3+] ≥ 1.2 × 1021 cm−3 (or [Er2O3] ≥ 2.65 mol. %) without OH− impurities being present.en© 2011 American Institute of PhysicsEnergy level decay and excited state absorption processes in erbium-doped tellurite glassJournal article002011470210.1063/1.36513990002965199000122-s2.0-8065513930926830Ebendorff-Heidepriem, H. [0000-0002-4877-7770]Ottaway, D. [0000-0001-6794-1591]