Extra-cavity, widely tunable, continuous wave MgO-doped PPLN optical parametric oscillator pumped with a Nd:YVO4 laser

An extra-cavity, widely tunable, and continuous wave (CW) singly resonant optical parametric oscillator (SRO) based on MgO-doped periodically poled lithium niobate (PPMgLN) has been developed. A Nd:YVO4 laser pumped by 808 nm laser diode array (LDA) is used as the pump source. The threshold value of the SRO system is only 1.86 W at 1064 nm. 1101.1 mW of idler output at 3.217 μm and 2004.3 mW of signal output at 1.590 μm have been achieved when the pump power is 8.76 W, and this corresponds to a total (idler + signal) optic–optic conversion efficiency of 35.5%. The periods of the domain structure on the PPMgLN wafer can be changed by shifting the PPMgLN crystal, thus enabling a widely tunable mid-infrared spectrum of 3.026–4.485 μm, and signal wavelengths widely tunable in range of 1.395–1.641 μm. Along with the signal and idler light, the visible and near-infrared spectrum (697.5–820.5 nm, 603.6–645.5 nm, 532 nm, 421.3–463.3 nm) is observed. This OPO system is compact, simple and operated at room temperature.