Optical properties of erbium-doped fluorochlorozirconate glasses

摘要

We report the optical properties of a fluorochlorozirconate (FCZ) glass with the composition 53% ZrF_4, 20% NaF, 3.5% AlF_3, 3% LaF_3, 0.5% InF_3, (20 - x)% BaCl2, x% BaF _2 with x varying from 0% to 2%, and doped with various amounts of trivalent erbium by the addition of ErCl_3. Annealing of the as-prepared glass in inert (N_2) or reducing (5%H_2 + 95%Ar) atmospheres at temperatures that ensure the conversion of the glass into a glass-ceramic by the nucleation of BaCl_2 nanocrystals, does not significantly change any of Er~(3+) related absorption and photoluminescence (PL) characteristics. We have carried out a Judd-Ofelt analysis of the absorption spectra and obtained Ω2 = (1.92 ± 0.3) × 10- 20 cm2, Ω4 = (0.88 ± 0.16) × 10~(- 20) cm~2 and Ω~6 = (0.59 ± 0.08) × 10~(- 20) cm ~2, and also the radiative lifetimes of the ~4I 1_(3/2)→~4I_(15/2), ~4I (11/2)→~4I_(15/2) and ~4S _(3/2)→~4I_(15/2) bands. The radiative lifetime from the Judd-Ofelt analysis for the ~4I_(13/2)→ ~4I_(15/2) band is in good agreement with the experimentally measured PL decay time. The examination of the optical properties of powdered samples with different average particle size does not show any photon trapping effects. We have determined the spectral absorption and emission cross-sections and then estimated the possible spectral optical gain for varying degrees of relative populations of the ~4I_(13/2) and ~4I _(15/2) manifolds.