Er³⁺-doped tellurofluorophosphate glasses for lasers and optical amplifiers

Absorption, fluorescence and decay properties of erbium-doped alkali tellurofluorophosphate glasses (RTFP) with the molar compositions of 50 (NaPO 3 ) 6 –10 TeO 2 –20 AlF 3 –19 RF–1 Er 2 O 3 (R = Li,Na or K) have been investigated in order to utilize these materials for the development of fibre amplifiers and lasers. The Judd–Ofelt (JO) model was applied to the absorption intensities of Er 3+ (4f 11 ) transitions to determine the JO intensity parameters Ω λ (λ = 2,4 or 6). These evaluated intensity parameters are used to calculate the spontaneous emission probabilities and branching ratios from the excited state J manifolds to the lower lying J ' manifolds of Er 3+ emission transitions. The radiative lifetimes of these excited states are determined from their respective spontaneous emission probabilities. Visible and NIR emission spectra have been studied for all three Er 3+ -doped tellurofluorophosphate glasses. In particular, for the emission at 1.5 µm corresponding to the transition, radiative parameters like the full width at half maximum (FWHM), emission cross-sections (σ e ) and figure of merit (FWHM × σ e ) were determined and compared with other hosts. The measured lifetimes of the 4 S 3/2 level are compared with predicted radiative lifetimes calculated from the JO theory. The potentiality of Er 3+ -doped tellurofluorophosphate glasses for devices such as lasers and optical amplifiers is discussed.