Effect of radiation trapping on spectroscopic properties of Er3+-doped oxide glasses

The absorption spectra, fluorescence spectra and the lifetimes of 4I13/2 level of Er3+-doped phosphate and tellurite glasses ha ve been measured for sample with different concentrations and thickness. The abs orption cross-section (σa), emission cross-section(σe), spontaneous emission probability(Arad), radiative lifetime(τrad ) and quantum efficiency(η) of fluorescence around 1.53 μm of Er3+-doped phosphate and tellurite glasses were determined. The effect of radia tion trapping on the spectral properties and parameters of Er3+-doped tellurite and phosphate glasses has been investigated. It was found that radiat ion trapping exists generally in erbium-doped glass hosts, even at low Er3+ -doping concentration (0.1 mol% Er2O3). Due to radia tion trapping, the values of the τrad of the Er3+∶4 I13/2 level in tellurite glasses increased about 11%—37％ with the sample thickness and erbium doping concentration, while in phosphate glasse s τrad increased by 6%—17%. The full-width at half maximum (FWHM)of fluorescence in tellurite glasses increased about 15%—64%, with 11%—55% for p hosphate glasses. It caused a high overestimation on the figure of merits (FOM) for amplifier bandwidth (σe×FWHM). The spectral overlap between the emission and absorption spectra in 1.53 μm band is relatively larger in tellur ite than in phosphate glasses, and values of the emission cross-section in tellu rite glasses are larger than that in phosphate glasses. Consequently, the radiat ion trapping in tellurite glasses is more severel than that in phosphate glasses .