CHARACTERIZATION OF ER3+-DOPED GLASSES BY FLUORESCENCE LINE NARROWING

The Stark levels of the 4I15/2 ground state manifold have been determined for Er3+-doped fluorozirconate, fluorophosphate, phosphate, and silicate bulk glasses from fluorescence-line-narrowing (FLN) measurements at 4.2 K. Splittings between adjacent Stark levels were observed to be 10-140 cm-1 and the total energy spread of the manifold was found to range from 335 to 400 cm-1. The position of a given Stark level varies up to 60 cm-1 depending on the particular Er3+ sites excited. Using the 4.2-K results, homogenous broadening is found to be a reasonable approximation for the 300-K luminescence band of the glasses examined. Results are also presented for silica preforms as well as for a barium-zinc-lutetium-thorium fluoride composition. The FLN studies together with a Judd-Ofelt [Phys. Rev. 127, 750 (1962); J. Chem. Phys. 37, 511 (1962)] analysis of the absorption data suggest similarities in the local environment between the fluorozirconates and the high-fluorine fluorophosphates.