ANALYSIS OF EXPERIMENTAL ND3-MICROSECOND DECAY COMPONENT AND A SUBSEQUENT NONEXPONENTIAL LONG-TERM DECAY WITH MONTE-CARLO SIMULATIONS( EMISSION TRANSIENTS WITH FAST SUB)

Our measurements of the emission of the F-4(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 an d high Er concentrations and our model gives a very good approach to t he experimental data. All transients show a fast sub-microsecond decay component and a subsequent non-exponential long-term decay. These tra nsient features are due to the non-radiative energy transfer from Nd-t o-Er ions that is driven by a fourfold interaction mixture, i.e., a di pole-dipole, dipole-quadrupole, quadrupole-quadrupole and exchange mix ture of interactions. At low Nd and Er concentrations the MC simulatio ns show that the short-and intermediate-range interactions can be negl ected, Several previously used models of the decay curves are describe d and evaluated as inadequate. (C) 1998 Elsevier Science B.V. All righ ts reserved.