Nd3+:YAG laser based on the 4F3/2 → 4I13/2 secondary transition with a phase-conjugate electro-optically Q-switched open multiloop cavity

Lasing on the ⁴F_3/2 → ⁴I_13/2 secondary transition (λ = 1.34 μm) in a Nd³⁺ : YAG laser with phase conjugation by fourwave mixing directly in the active laser medium was experimentally studied in the regime of electro-optic Q-switching of an open multiloop cavity. The use of an electro-optic Q-switch with a controllable delay of its opening made it possible to increase the amplitude and temporal stabilities of the output laser parameters. The maximum laser pulse energy was 100 mJ at a pulse duration of 120 ns. The phase-conjugate radiation divergence was 0.8 mrad at beam quality M²_x = M²_y = 1.3. Nonlinear optical conversion of 1.34 μm laser radiation to visible radiation was achieved experimentally. Second and third harmonic generation at wavelengths of 0.67 and 0.446 μm with conversion efficiencies of 25% and 8%, respectively, was demonstrated.