Enhancing near-infrared emission in Nd3+/Er3+ tellurite glasses through Cr3+ co-doping

Numerous applications of rare-earth (RE) doped glasses can benefit from energy transfer between the glass matrix and the doped-in RE ions. To investigate the electronic processes involved in this energy transfer, we prepared tellurite glass samples doped with RE ions (Nd 3+ or Er 3+ ), transition metal ions (Cr 3+ ), and samples co-doped with both. We examined their optical properties at room temperature and at 4 K, focusing on absorption spectra and photoluminescence behaviour. Our results show that the near-infrared emission of Nd 3+ and Er 3+ is significantly enhanced by excitation of glassy network via Cr 3+ absorption in the co-doped samples, with enhancement factors of approximately 7-fold for Nd 3+ and 2-fold for Er 3+ at room temperature. The broad emission band of Cr 3+ ions overlaps spectrally with the absorption bands of both RE ions, allowing for energy transfer. We propose that this provides an effective way to enhance NIR emission from RE-doped tellurite glasses through transition metal co-doping.