Tellurite glasses following the molar concentration 71.5% TeO2, 22.5% WO3, 5% Na2O and 1.5% Nb2O5 have been investigated. Samples doped with Tm2O3, Pr2O3, Yb2O3 or Bi2O3 were fabricated by the conventional melt quenching process. Rare-earth (RE) 3+ ions have well defined emission bands. On the other hand, Bismuth emission in the infrared region have been found in some glasses and even that emission laser have been already obtained, the mechanism behind its luminescence is still misunderstood. The Bismuth emission is sometimes referred as a “superbroadband” emission around 1.3um, which is very promising for an optical amplifier, but, to the best of our knowledge a bismuth based optical amplifier have not been produced yet. Our purpose is to investigate the mechanism behind this misunderstood “superbroadband” luminescence, and compare it with the rare-earths properties in the same range. The characterization consists in measurements of optical absorption spectra, optical emission spectra and life-time decay. Differential thermal analysis (DTA) was also performed, to identify changes in T<sub>g</sub> and T<sub>x</sub> as function of the doping concentration, which is important to the drawing process of a fiber.
Thulium doped Samarium codoped tellurite-tungstate glasses were produced. Luminescence properties in the infrared region were investigated looking to observe improved properties for S-band amplification in the co doped samples. Thulium is well-known by the <sup>3</sup>H<sub>4</sub>-<sup>3</sup>F<sub>4</sub> radiative transition emitting around ~1.47μm, which is a self-terminating transition in tellurite hosts due the longer lifetime of the lower level in relation to the upper level of this transition. Analysis of absorption and emission spectra showed that we could quench the 3F4 level significantly, what improved the intensity of the emission at 1.49μm. However, the state <sup>3</sup>H<sub>4</sub> were also quenched due the cross relaxation process due the absorption bands of Sm<sup>3+</sup> around 1.5μm.