Temperature-tunable nanosecond optical parametric oscillator based on periodically poled MgO:LiNbO3MgO:LiNbO3

We report a compact quasi-phase-matched optical parametric oscillator (OPO) using periodically poled MgO-doped LiNbO3LiNbO3 with different grating periods. The OPO is pumped by a diode-pumped passively Q-switched Nd:YAG laser providing 4.8-ns pulses at 5.4-kHz repetition rate. The OPO generates signal and idler wavelengths tunable in the ranges of 1.5–1.7μm and 2.8–3.6μm, respectively, by changing the crystal temperature between room temperature and 170∘C. The temperature-dependent Sellmeier equation for the extraordinary refractive index of MgO-doped LiNbO3LiNbO3 is modified in the Mid-IR region, which gives an accurate prediction of the experimental temperature-tuning results. The linewidth of the signal wave is in the range of 0.5–1.0 nm without any controlling element.