Lasing in Y3Al5O12:Er3+ (λ = 2.94 μm) crystals as a result of selective excitation of the lower active level

Lasing was induced in Y_1.5Er_1.5Al₅O₁₂ (λ = 2.94 μm) crystals by selective pumping of the electronic–vibrational wing of the ⁴I_15/2–⁴I_13/2 transition. A population inversion was established in this YAG:Er³⁺ laser by a strong interaction between the excited Er³⁺ ions at the ⁴I_13/2 level and the transfer of energy from the lower active level to the upper one in accordance with the ⁴I_13/2–⁴I_9/2, ⁴I_13/2–⁴I_15/2 scheme.