Emission enhancement of Er3+–doped oxide- and oxyfluoro-tellurite glass thin films on silicon for photonic integrated chips: the effect of thermal annealing in oxygen atmosphere

Er3+-doped tellurite and oxyfluoro-tellurite glasses are attractive active materials for integrated photonics because of their high refractive index, broad infrared transparency, and high rare-earth solubility. Here, those glasses were converted into thin films on silicon by pulsed laser deposition (PLD), allowing complex glass compositions to be deposited as thin films. Since as-deposited PLD films often show reduced luminescence due to structural disorder, defects, and hydroxyl-related quenching, we investigated the effect of post-deposition annealing in an O2 atmosphere. Under 980 nm excitation, both oxide andoxyfluoro-tellurite films exhibit visible and near-infraredemission. The emission intensity and effective lifetime increase with annealing, reaching optimum values after 6h, with lifetimes ~ 2 ms. Longer annealing times reduce the emission, suggesting the activation of additional non-radiative pathways associated with enhanced Er3+–Er3+ interactions or partial clustering. These results define an optimized annealing window for Er3+-doped tellurite films for silicon-compatible photonic devices in the telecom band.