Optical spectroscopy of lanthanide ions in ZnO-TeO2 glasses

Zinc tellurite glasses of compositions 19ZnO-80TeO(2)-1Ln(2)O(3) with Ln = Eu, Er, Nd and Tm were prepared by melt quenching. The absorption spectra w ere measured and from the experimental oscillator strengths of the f -->f t ransitions the Judd-Ofelt parameters Omega (lambda) were obtained. The valu es of the Omega (lambda) parameters are in the range usually observed for o xide glasses. For Nd3+ and Er3+, luminescence spectra in the near infrared were measured and the stimulated emission cross sections sigma (p) were eva luated for some laser transitions. The high values of sigma (p), especially for Nd3+ make them possible candidates for optical applications. Fluoresce nce line narrowing (FLN) spectra of the Eu3+ doped glass were measured at 2 0 K, and the energies of the Stark components of the F-1(1) and F-7(2) stat es were obtained. A crystal field analysis was carried out assuming a C-2 n u site symmetry. The behaviour of the crystal field ratios B-22/B-20 and B- 44/B-40 agrees reasonably well with the values calculated using the geometr ic model proposed by Brecher and Riseberg. The crystal field strength at th e Eu3+ sites appears to be very low compared to other oxide glasses. (C) 20 01 Elsevier Science B.V. All rights reserved.