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 (NaPO3)(6)-1 0 TeO2-20 AlF3-19 RF-1 Er2O3 (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 Er3+ (4f(11)) transitions to determine the JO intensity parameters Omega(lambda) (lambda = 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 Er3+ 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 Er3+-doped tellurofluorophosphate glasses. In particular, for the emission at 1.5 mu m corresponding to the 4I(13/2) -> I-4(15/2) transition, radiative parameters like the full width at half maximum (FWHM), emission cross-sections (sigma(e)) and figure of merit (FWHM x sigma(e)) were determined and compared with other hosts. The measured lifetimes of the 4S(3/2) level are compared with predicted radiative lifetimes calculated from the JO theory. The potentiality of Er3+-doped tellurofluorophosphate glasses for devices such as lasers and optical amplifiers is discussed.