Abstract
A comparative study of the spectroscopic properties at 1.5 μm of erbiumdoped fluoride and tellurite glasses has been performed. Emission in the third telecommunications window has been observed upon excitation at 514.5 nm and the lifetime of the 4I13/2 level has been measured. Infrared-to-visible upconversion emission upon continuous-wave laser excitation at 976 nm has been detected in the different hosts. The upconversion results in green and red emissions, whose intensity has a quadratic dependence on the excitation power. Lifetime measurements have been performed in order to clarify the contributions of excited-state absorption and energy transfer to the upconversion process.