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

Author(s)

Gomes, Laercio ^[1] ; Oermann, Michael ^[2] ; Ebendorff-Heidepriem, Heike ^[2] ; Ottaway, David ^[2] ; Monro, Tanya ^[2] ; Henriques Librantz, Andre Felipe ^{[1, 3]} ; Jackson, Stuart D. ^[4]

Affiliation

^[1] IPEN CNEN SP, Ctr Lasers & Applicat, BR-05422970 Sao Paulo - Brazil

^[2] Univ Adelaide, Inst Photon & Adv Sensing, Adelaide, SA 5005 - Australia

^[3] UNINOVE, Dept Sci, BR-01156050 Sao Paulo - Brazil

^[4] Univ Sydney, Sch Phys, Inst Photon & Opt Sci, Camperdown, NSW 2006 - Australia

• Document type: Journal article
• Source: Journal of Applied Physics; v. 110, n. 8 OCT 15 2011.
• Web of Science Citations: 37

Abstract

The fundamental excited state decay processes relating to the (4)I(11/2) -> (4)I(13/2) transition in singly Er(3+)-doped tellurite (TZNL) glass have been investigated in detail using time-resolved fluorescence spectroscopy. Selective laser excitation of the (4)I(11/2) energy level at 970 nm and selective laser excitation of the (4)I(13/2) 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 (4)I(13/2) level populates the (4)I(11/2) upper laser level of the 3 mu m transition. This upconversion has been analyzed for Er(2)O(3) concentrations between 0.5 mol. % and 2.2 mol. %. The (4)I(13/2) and (4)I(11/2) 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 mu m emission efficiency is due to the non-radiative decay bridging the (4)I(11/2) -> (4)I(13/2) transition and energy transfer to the OH(-) groups in the glass. Excited state absorption was observed to occur from the (4)I(13/2) and (4)I(11/2) levels with peak absorptions occurring at 1550 nm and 971 nm, respectively. The decay time of the (4)I(11/2) excited state decreased with an increase in the Er(3+) concentration, which related to energy transfer to OH(-) ions that had a measured concentration of 6.6 x 10(18) cm(-3). Results from numerical simulations showed that a population inversion is reached at a threshold pumping intensity of similar to 80 kW cm(-2) for a cw laser pump at 976 nm if {[}Er(3+)] >= 1.2 x 10(21) cm(-3) (or {[}Er(2)O(3)] >= 2.65 mol. %) without OH(-) impurities being present. (C) 2011 American Institute of Physics. {[}doi:10.1063/1.3651399] (AU)