Rare-earth-activated fluoride and tellurite glasses: optical and spectroscopic properties

In this work we report on spectroscopic properties of Er 3+ -doped aluminum fluorophosphate glasses of molar composition 29.8AlF 3 :3.5 MgF 2 : 19.8 CaF 2 : 10.9 SrF 2 : 12.8 BaF 2 : 8.4 YF 3 :9.8 ZrF 4 :4 NaPO 3 :1 ErF 3 and 30 AlF 3 :3.5 MgF 2 :20 CaF 2 : 11 SrF 2 : 13 BaF 2 : 8.4 YF 3 : 10 ZrF 4 : 4 NaPO 3 : 0.1 ErF 3 , and Er 3+ -doped tellurite glasses of molar composition 75 TeO 2 : 12 ZnO: 10 Na 2 O: 2 PbO: 1 Er 2 O 3 and 75 TeO 2 : 12 ZnO: 10 Na 2 O: 2 GeO 2 : 1 Er 2 O 3 . Absorption and Stokes luminescence upon visible excitation were measured. Emission in the third telecom window was observed upon excitation at 514.5 nm and the lifetime of the 4 I 13/2 level was measured. IR-to-visible up conversion emission under continuous-wave laser excitation at 976 nm was observed. The up conversion results in a strong green emission and a weaker red emission, whose intensity shows a quadratic dependence on the excitation power, indicating that two photons are involved in the process. Lifetime measurements were performed in order to study the dynamical behavior of the up conversion emission and to clarify the contributions of excited state absorption and energy transfer to the up conversion process.