This paper presents a detailed spectroscopic investigation of zinc tellurite glasses with the compositions (0.80 - x - y) TeO2 + (0.20) ZnO + xEr(2)O(3) + yYb(2)O(3) (x = 0, y = 0; x = 0.004, y = 0; x = 0, y = 0.05 and x = 0.004, y = 0.05 per moles). The samples were synthesized by the conventional melt quenching method. The optical absorption and emission measurements were conducted at room temperature to determine the spectral properties of lanthanides doped zinc tellurite glasses and, to study the energy transfer processes between dopant lanthanide ions. The band gap energies for both direct and indirect possible transitions and the Urbach energies were measured from the absorption spectra. The absorption spectra of the samples were analyzed by using the Judd-Ofelt approach. The effect of the ytterbium ions on the emission properties of erbium ions was investigated and the energy transfer processes between dopant ions were studied by measuring the up-conversion emission properties of the materials. The color quality parameters of obtained visible up-conversion emission were also determined as well as possibility of using the Er3+ glasses as erbium doped fiber amplifiers at 1.55 pm in infrared emission region. (C) 2016 Elsevier B.V. All rights reserved.