Green to red and NIR tunable luminescence in heavily Er3+-doped tellurite glasses via selective energy transfer mechanism

Here, we select simple Er 3+ -doped tellurite glass as model system to systematically explore the up-conversion, down-shifting mechanisms with different excitations (980 and 447 nm), respectively. We observe for the first time, to the best of our knowledge that tunable photo-luminescence occurs from green to red and NIR region, rather than merely from the long-accepted green to red region. Direct evidence of selective energy transfer mechanism is expounded in detail, and its potential applications are demonstrated. In addition, we provide evidence that the cross-relaxation process between dopant ions can enhance photo-luminescence in Er 3+ doped tellurite glasses with high dopant concentrations, whereas the crucial reason for emission decrease is the energy loss long-distance energy migration. These fundamental insights into the photophysical processes in heavily doped photonic glasses will broaden the applications of rare-earth-doped materials ranging from optical communications to medical imaging.