532 nm pumped optical parametric oscillator in bulk periodically poled lithium niobate

We report a quasi-phase-matched optical parametric oscillator (OPO) pumped by the second harmonic of a single frequency Q-switched Nd:YAG laser. Both the frequency doubling to 532 nm and the parametric oscillation are performed in periodically poled lithium niobate crystals with a nonlinearity of ∼15 pm/V. The OPO has been operated in ‘‘singly resonant’’ and ‘‘doubly resonant’’ configurations. The threshold in the singly resonant case was ∼0.14 J/cm2, more than one order of magnitude below the damage limit. OPO tuning from 945 to 1225 nm was achieved by changing both the period of domain reversal (from 6.8 to 6.85 μm) and the temperature of the crystal.