Mechanism of a population inversion between the⁴<i>I</i>_11/2and⁴<i>I</i>_13/2levels of the Er³⁺ion in Y₃AI₅O₁₂crystals

Abstract

Studies of the spectra of stimulated emission from Y3AI5O12:Er3+ crystals (4I11/2–4I13/2) containing 20 wt.% activator ions, showed that, as the temperature decreased from 300 to 77°K, a change was observed in the emission wavelength (at T = 300°K it was found that λ1 = 2.9364 μλ2 = 2.8310μ and at T = 77°K it was found that λ1 = 2.6930 μ, λ2 = 2.8970 μ). This could not be attributed to a thermal redistribution of the populations of the Stark components of the 4I11/2 and 4I13/2 upper and lower active levels. An analysis of the results showed that the temperature shift of the stimulated emission spectrum was due to changes in the processes of relaxation of excitation from the upper levels of the Er3+ ion which caused substantial changes in the populations of the 4I11/2 and 4I13/2 multiplets.