Continuous-wave mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate

This paper reports a continuous-wave (CW) mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate (PPLN) pumped by a diode-end-pumped CW Nd:YVO_4 laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN's grating period of 28.5 \mum and the temperature of 140℃, the maximum idler output power of 155 mW at 3.86 \mum has been achieved when the 808 nm pump power is 8.5 W, leading to an optical-to-optical conversion efficiency of 1.82%.