Spectroscopy and frequency upconversion in Nd3+-doped TeO2-TiO2-Nb2O5 glass

摘要

In this work, we report the optical properties of Nd3+ ions in tellurite glasses (TeO2-TiO2-Nb2O5) for two different Nd3+ concentrations. Judd-Ofelt intensity parameters were derived from the absorption spectrum and used to calculate the radiative lifetime and stimulated emission cross section of the F-4(3/2). I-4(11/2) transition. The non-exponential character of the decays from the F-4(3/2) level and the reduction of the lifetime even at low temperature as Nd3+ concentration increases reveal the presence of nonradiative processes. The time evolution of the decays from the F-4(3/2) level is consistent with a dipole-dipole direct energy transfer mechanism. Upconversion processes that produce green, orange, and red emissions after infrared excitation in the F-4(3/2) and F-4(5/2) levels have been investigated by using steady-state and time-resolved laser spectroscopy. The characteristics of the excitation spectra together with the temporal behaviour of the decays from the upconverted luminescence suggest that energy transfer upconversion processes are the dominant mechanisms in such emissions.