Simulation of the optical properties of Er:ZBLAN glass

Absorption and emission spectra of Er ³⁺ -doped ZBLAN glass at room temperature were estimated from structural models prepared by using molecular dynamics (MD) simulation based on crystal field theory and point-charge approximation. The calculated absorption and emission spectra substantially agreed with the observed ones. Furthermore, it was found that the emission spectra at low temperatures could be also reproduced to some extent. The relation between the splitting of the energy level and the crystal field parameters calculated from the Er ³⁺ ion in each structural model was examined. According to this relation, the energy levels could be classified into several groups. The splitting of the group represented by the 4 I 9/2 level was dominated by the short-range structure around the Er ³⁺ ions. The transition process for the measurement of the well-defined fluorescence line narrowing (FLN) spectrum was estimated from the characteristics of the splitting of the energy levels.