Stimulated emission from a neodymium-doped gadolinium gallium garnet crystal due to the 4F3/2–4I13/2 (λ = 1.33 μm) transition

The development of a neodymium-doped gadolinium gallium garnet (GGG:Nd) crystal laser utilizing the ⁴F_3/2–⁴I_13/2 transition (lasing wavelength λ = 1330 nm) is reported. A GGG:Nd crystal 8 mm in diameter and 80 mm long was operated under free-running multimode conditions, using an exit mirror with the reflection coefficient R = 81%. The lasing threshold was 5 J and the differential efficiency was 1.54%. A pump pulse of energy E_p = 34.2 J generated a laser radiation pulse of energy E_l = 417 mJ. When the pump pulse repetition frequency was 50 Hz and the energy was 64 J, the average free-running power was ~ 40 W. The experimental dependences E_l (E_p, R) were used to estimate the loss factor κ, the lasing transition cross section σ, and the maximum differential efficiency η₀. The following values of these parameters were obtained: κ ≈ 0.09, σ = (1.1 ± 0.2) X 10^–19 cm², and η₀ = 2.2%.