Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) ; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) ; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) ; Processo FAPESP: 140459/2011-1 ; Processo FAPESP: 305063/2012-0 ; Processo FAPESP: 307943/2012-7 ; Processo FAPESP: 306970/2011-2 ; Processo FAPESP: 306950/2011-1 ; In this work we report the observed downconversion (DC) mechanism in Er3+/Yb3+-codoped tellurite glasses (in mol%, 80TeO(2)-10Li(2)O-10TiO(2)). The samples were synthesized by the conventional melt-quenching method and then studied using optical spectroscopy and thermal lens spectroscopy (TLS). These characterizations enabled investigation of the radiative and nonradiative processes involved in energy transfer from erbium to ytterbium. The visible Er3+ fluorescence intensities decreased as a function of the Yb3+ concentration, and there was a corresponding increase in the ytterbium emission at around 980 nm. Simultaneously, there was a reduction in the heat-generated due nonradiative decays (similar to 21%) when ytterbium was added. This temperature change was measured by TLS measurements and the results corroborate with the indicated by spectroscopic interpretation. (C) 2014 Elsevier B.V. All rights reserved.