Spectral Broadening of Europium Ions in Glass

The fluorescence and absorption spectra of trivalent europium ions in glass were measured and compared with the spectra of single crystals of ${\mathrm{Gd}}_2$ ${\mathrm{O}}_3$: Eu. It was determined that there is a great similarity between the optical properties of the rare-earth glasses and rare-earth sesquioxide crystals. The spectral studies showed that the europium ions locate in two, and possibly three, average environment sites in glass, mirroring the three sites in which the ion locates in the monoclinical form of the sesquioxide. The primary broadening mechanism was found to be inhomogeneous as determined by the temperature independence of the spectral half width and peak wavelength in the range from 4 to 300°K. This inhomogeneous broadening arises from the heterogeneity of the ion environment in glass.