Improved photoluminescence emission in Er-doped oxyfluorotellurite thin films

Abstract

Current optical telecommunication systems are mainly based in the 4I13/2->4I15/2 emission transition of Er3+ ions at 1.5 µm, although the glass host in which the ions are embedded may influence their photoluminescence (PL) emission characteristics. In this regard, oxyfluorotellurite glasses present many advantages over other glasses, such as: a wide transmission region (0.35-6 µm), low phonon energy, high refractive index, good glass stability and high corrosion resistance. Moreover, they show a high rare-earth ion solubility, which is of great importance to develop active optical devices. In this work we exploit the advantages of pulsed laser deposition to produce oxyfluorotellurite thin film glasses of the system TeO2-ZnO-ZnF2 doped with 1 %wt. ErF3. Transparent films were synthesized at room temperature in an oxygen pressure of 10 Pa using a laser energy density of 2 J/cm2. Films have been characterized structurally and optically. Transparent films resulted enriched in oxygen and with a small reduction of fluorine compared to the bulk glass, while their optical properties remained similar to that of the target glass, PL at 1.5 µm has been studied before and after film annealing at different temperatures. It is noticeable a great PL intensity increase for some heat treatments. The evolution of the PL lifetime and intensity is discussed in terms of the effect of annealing on the glass structure and the probability of nonradiative energy transfer between Er3+ ions.