Stark levels analysis for Er3+-doped oxide glasses:: germanate and silicate

A model of effective crystal field Hamiltonian based on the principle of descending symmetry and using the symmetry group chain scheme is proposed to describe the average of local symmetries occupied by rare earth (RE) ions in glasses. Only three crystal field parameters, one for each rank, have to be fitted in this Hamiltonian. Based on the absorption and emission spectra measured in a conventional way at 13 K, the Stark levels in manifolds from I-4(15/2) to H-2(9/2) and their widths of Er3+ in two oxide glasses: germanate and silicate, are investigated. In the process, the scalar crystal field strength, homogeneous and inhomogeneous effective widths of levels are analyzed, and the former models and results about optical properties of rare earth ions in glasses are discussed. The cubic crystal field term is found to give the major contribution to the crystal field strength around the rare earth ion when the weak axial distortion completely removes the degeneracy. (C) 2001 Elsevier Science B.V. All rights reserved.