Spectroscopy of gadolinium gallium garnet crystals doped with Y b3 + revisited
The optical spectroscopy measurements of gadolinium gallium garnet (GGG) crystals doped with Yb show evidence of the presence of non-equivalent optical centers with very similar radiative decay rates. The energy level schemes of those centers have been determined on the basis of optical absorption, luminescence and Raman experiments. Crystal field fitting resulted in two sets of slightly different crystal field parameters for two non-equivalent Yb centers. Both sets of parameters describe perfectly the experimentally detected Y b3 + energy levels. Correlation between systematic trends in the experimental energy level schemes and crystal field parameters is discussed.
Dopant distribution and energy transfer processes in crystals
Abstract This paper discusses the effects of the mutual asymmetric crystal field perturbations produced by near active and sensitizer ions in co-doped crystals. It is shown that modification of the spectral and dynamic properties of the perturbed ions justifies the division of the active and sensitizer ions systems in homogeneous subsystems and the particularities of energy transfer processes in these subsystems are presented. The discussion is illustrated for active rare earth ions in garnet crystals sensitized by Cr3+ (in octahedral sites), Fe3+ (in tetrahedral sites) or Yb3+ (in dodecahedral sites). It is thus shown that the emission in sensitized laser crystals manifests different spectral and temporal properties from crystals with simple activation.
Effects of energy transfer on quantum efficiency of YAG:Nd
Using the energy transfer parameters deduced from the study on nonexponential luminescence decay of the 4F3/2 level of Nd3+ in YAG at room temperature, it is shown that up to 1.5 at. % Nd, the relative quantum efficiency is reduced by an amount of 18.2C, C being the relative (to Y3+) Nd concentration. It is pointed out that about 20% of this reduction is due to a very effective quenching mechanism inside the nearest‐neighbor Nd‐ion pairs.