Spectral and kinetic properties of Er3+, Yb3+ : Yb3Al5O12 crystals at high temperatures

The spectral and kinetic properties of yttrium–aluminium garnet crystals co-doped with Er³⁺ and Yb³⁺ are studied in the range from room temperature to 800 °C. It is found that the lifetime of the ⁴I_11/2 level of the erbium ion decreases approximately by a factor of twenty with increasing temperature and the efficiency of nonradiative energy transfer from Yb³⁺ to Er³⁺ increases considerably. Analytic expressions describing the spectral and temperature dependences of the absorption and emission cross sections for the transition between the ⁴I_13/2 and ⁴I_15/2 levels of the erbium ion are proposed.