Intensities of hypersensitive transitions in garnet crystals doped with Er3+ ions

We examine the oscillator strengths and the intensity parameters Ω t (t = 2, 4, 6) of yttrium-aluminum, scandium-containing, and gallium garnet crystals doped with Er3+ ions. A comparative analysis of the oscillator strengths and the intensity parameters Ω t (t = 2, 4, 6) of garnets with different contents of Al3+ and Sc3+ ions (Gd2.4Er0.5Sc1.8Al3.3O12, Gd2.4Er0.5Sc1.9Al3.2O12, Gd2.4Er0.5Sc2.0Al3.1O12) is performed, as a result of which the oscillator strengths and the intensity parameters Ω t (t = 2, 4, 6) of these crystals are shown to have close values. We find that Ca3(NbGa)5O12 crystals doped with Er3+ ions are characterized by highest values of the oscillator strengths for hypersensitive transitions and of the intensity parameter Ω2 of Er3+ ions compared to the values of these quantities in the examined garnet crystals, which is determined by the fact that the symmetry of the local environment of Er3+ ions in these crystals is C 1, C 2, or C 2ν. We reveal that, as the concentration of Er3+ ions in these crystals increases from 1 to 39 at %, both the oscillator strength of the hypersensitive transition 4 I 15/2 → 2 H 11/2 of Er3+ ions and their intensity parameter Ω2 tend to decrease, which can be related to an increase in the relative fraction of Er3+ ions with higher symmetry of the local environment.