Effect of Nb2O5 on the ∼2.0 μm band luminescence of Ho3+/Tm3+/Ce3+ tri-doped tellurite glass

In this work, the effect of Nb2O5 oxide on the similar to 2.0 mu m band luminescence of Ho3+/Tm3+/Ce3+ tri-doped tellurite glass with composition of TeO2-ZnO-La2O3 was studied. The doped tellurite glass was synthesized by using the melt-quenching method. Under the pumping of 808 nm laser diode (LD), a broad and relatively flat fluorescence emission ranging from 1600 to 2200 nm with a full width at half maximum (FWHM) of 374 nm was obtained by optimizing the concentration combination of Ho3+, Tm3+ and Ce3+ ions. The observed broad luminescence was attributed to the spectral overlapping between the energy level transitions from F-3(4) to H-3(6) of Tm3+ at 1.82 mu m and that from I-5(7) to I-5(8) of Ho3+ at 2.0 mu m. Further, an increment by about 143% in peak intensity of 1600 similar to 2200 nm broad luminescence was found after the introduction of Nb2O5 oxide, which is due to the enhanced energy transfer from Tm3+ to Ho3+ ions, and the increased multi-phonon relaxation (MPR) rate from higher levels to fluorescence emitting levels. It can be inferred from the results that a potential gain medium suitable for applications in optoelectronic devices operating at similar to 2.0 mu m band can be produced by incorporating an appropriate amount of Nb2O5 oxide into Ho3+/Tm3+/Ce3+ tri-doped tellurite glass.