Optical properties of erbium-doped fluorochlorozirconate glasses

Abstract

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)% BaCl 2, 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 Ω 2 = (1.92 ± 0.3) × 10 − 20 cm 2, Ω 4 = (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 13/2→ 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.