Spectroscopic and 1.06 mu m laser properties of Nd~(3+)-doped K-Sr-Al phosphate and fluorophosphate glasses

摘要

Optical absorption, fluorescence and decay curves for the~4F_(3/2) level of Nd~(3+) ions in phosphate (P_2O_5-K_2O-SrO-Al_2O_3) and fluorophosphate (P_2O_5-K_2O-SrO-Al_2O_3-AlF_3 and P_2O_5-K_2O-SrO-Al_2O_3-BaF_2) glasses doped with three concentrations (0.1, 1.0 and 2.0mol percent) of Nd~(3+) ions have been investigated. The Judd-Ofelt (JO) theory has been applied to the absorption spectra of 1.0mol precent Nd~(3+)-doped glasses to derive JO intensity parameters which are in turn used to calculate the radiative properties of the Nd~(3+) ion fluorescent levels. The assigned energy level data of Nd~(3+) (4f~3) ions are analysed in terms of a parametrized free-ion Hamiltonian model that consists of 20 interaction parameters of atomic nature. The stimulated emission cross section and branching ratios have been calculated using the emission spectra. The relatively higher branching ratio for ~4F_(3/2) - >~4I_(11/2) transition shows the suitability of these glasses for laser application. It is interesting to note that the measured decay curves of the~4F_(3/2) level remain nearly single exponential even for higher Nd~(3+) ion concentration but with shortening of lifetime.