Analysis of experimental Nd 3+ emission transients with fast sub-microsecond decay component and a subsequent non-exponential long-term decay with Monte-Carlo simulations

Abstract

Our measurements of the emission of the 4F 3/2 state of Nd in Nd–Er-codoped garnet crystals and other measurements found in the literature are analyzed with Monte-Carlo simulations. All samples have low Nd and high Er concentrations and our model gives a very good approach to the experimental data. All transients show a fast sub-microsecond decay component and a subsequent non-exponential long-term decay. These transient features are due to the non-radiative energy transfer from Nd-to-Er ions that is driven by a fourfold interaction mixture, i.e., a dipole–dipole, dipole–quadrupole, quadrupole–quadrupole and exchange mixture of interactions. At low Nd and Er concentrations the MC simulations show that the short- and intermediate-range interactions can be neglected. Several previously used models of the decay curves are described and evaluated as inadequate.