Luminescence of erbium-doped bismuth–borate glasses

Absorption and luminescence properties of erbium ions in the binary glass system bismuth oxide (Bi2O3)–boric oxide (B2O3) are measured for the composition range 25–65 mol% Bi2O3. A Judd–Ofelt analysis of the typical erbium bands in the absorption spectra reveals comparably high Judd–Ofelt coefficients. This indicates a substantial mixing of other electronic configuration into the 4fN configuration by the random crystal fields in the glasses. All coefficients are decreasing with increasing Bi2O3 content, this effect being most pronounced with Ω2. Luminescence decay times and radiative efficiencies show an expressed dependence on the glass composition. Radiative efficiencies of all luminescence bands increase with increasing Bi2O3 content—accompanied, however, by a slight narrowing of the bands. Except the common luminescence bands of erbium, upconversion luminescence at a wavelength of 0.54 μm could be detected.