Er3+-doped fluorotellurite thin film glasses with improved photoluminescence emission at 1.53 µm

•Transparent Er-doped fluorotellurite films are produced by pulsed laser deposition.•Post-deposition thermal treatments are required to activate Er3+ photoluminescence.•4I13/2→4I15/2 emission spectrum is similar for bulk and annealed film glasses.•4I13/2 level fluorescence decay is shorter in annealed films than in bulk glasses.•Photoluminescence response relates to hydroxyl groups concentration in film glasses.

Transparent oxyfluoride tellurite thin film glasses have been produced at room temperature by pulsed laser deposition in O2 atmosphere from an Er-doped TeO2-ZnO-ZnF2 bulk glass. Thin film glasses present high refractive index (n≥1.95) and good transparency (T≥80%) in the visible (λ>400 nm) and near infrared range. However, their photoluminescence (PL) performance at 1.5 μm is poor. Thermal annealing at moderate temperatures (T≤315 °C), well below glass crystallization, increases the PL intensity by more than one order of magnitude as well as the PL lifetime up to τ≈3.3 ms. Film glasses present a larger fraction of TeO3 trigonal pyramids than the bulk glass and a very large OH− content. The structure and composition of film glasses do not change upon annealing and thus the activation of the PL response is related to the improvement of the surface morphology and the significant decrease of their OH− content.