Passively Q-switched diode pumped Nd:YAG laser with intracavity optical parametric oscillator

The peak power of 0.65 MW and energy of 1.9 mJ at 1572 rim-wavelength was demonstrated in a singly resonant diode pumped intracavity optical parametric oscillator (IOPO). The energy of 4.3 mJ in fundamental mode at 1064 nm-wavelength with 15 ns-pulse duration in passively Q-switched regime was achieved in the arranged for IOPO Nd:YAG slab laser pumped by 300 W quasi-cw diode array. The KTP crystal, size of 20x5x5 mm(3), 'x-cut' for non-critically phase-matched parametric generation at the signal wavelength of 1572 nm was used in experiments. In optimized, with respect to single pulse energy, IOPO cavity with output coupler of 50% transmission at signal wavelength the five-fold shortening of signal pulse duration with respect to 1064 rim pump radiation was observed. The twice-higher level of signal peak power of 650 kW, compared to pump laser at 1064 run in the same cavity without OPO, was achieved. The conversion efficiency of 44% with respect to 1064 nm pump beam and 3.8% with respect to diode pump energy was demonstrated.