Effect of radiation trapping on the emission properties of Er3+: 4I13/2 → 4I15/2 transition in oxide glasses

The effect of radiation trapping on the emission properties of Er3+-doped tellurite and phosphate glasses has been investigated as the function of sample thickness and doping concentration. It was found that radiation trapping exists generally in two glass matrices, even at low doping concentration (⩽0.1 mol% Er2O3). The larger effect of radiation trapping in tellurite glasses compared with phosphate glasses is due to its larger emission cross-section at 1.5 μm band and the spectral overlap between the emission and absorption spectra of Er3+: 4I13/2 ↔ 4I15/2transition. Due to radiation trapping, the measured lifetime of the Er3+: 4I13/2 level in tellurite glasses increases by about 11–37% with increasing the sample thickness at the different erbium doping concentration, while 6–17% for phosphate glasses. And the full-width at half maximum of fluorescence (FWHM) of Er3+: 4I13/2 → 4I15/2 transition in tellurite glasses increased by about 15–64% with increasing the sample thickness, while 11–55% for phosphate glasses. It caused a high overestimation on the figure of merits (FOM) for amplifier bandwidth (σe × FWHM).