Judd-Ofelt parameter analysis and spectroscopic properties of Er3+-doped phosphate glasses

The spectroscopic properties and fluorescent up-conversion of Er3+ ions-doped phosphate glasses have been studied in this work. The effect of Al2O3 contents and Yb3+ co-doping concentration on the spectroscopic properties and up-conversion was explored. According to Judd-Ofelt(J-O) theory, J-O parameters, Omega(t) ( t = 2, 4, 6) of erbium phosphate glasses have been calculated from the measured absorption spectra. The glasses with lower Al2O3 contents have larger Omega(4) and slightly larger Omega(2). The Yb3+ ion concentration does not affect J-O parameters. The oscillator strength, spontaneous emission probability, quantum efficiency, up-conversion coefficient of Er3+ have been calculated from the measured fluorescent lifetime and the calculated J-O parameters. The stimulated emission cross section of Er3+ ions was calculated by using McCumber theory. It is found that the stimulated emission cross section of Er3+ ion is larger in the glass with lower Al2O3 concentration. The Yb3+ ion concentration strongly affects the up-conversion intensity of the glasses studied. It increases with Yb3+ ion concentration. It is deduced from experiment results that the double-photon absorption involves the up-conversion process. The calculated up-conversion coefficient is small in Er3+ phosphate glasses. It is mainly determined by Er3+ ion concentration. After water removing treatment, the quantum efficiency can be larger than 90% in the erbium phosphate glasses.