Synchronously pumped mid-infrared optical parametric oscillator with an output power exceeding 1W at 4.5 m

The generation of tunable mid-infrared picosecond laser radiation in a synchronously pumped optical parametric oscillator (OPO) based on periodically poled lithium niobate (PPLN) is reported. Numerical calculations were used to optimize the crystal length in order to balance the parametric gain and the absorption losses in the high-absorption regime of lithium niobate. Due to the numerical results, the system was systematically optimized for the mid-infrared output power. An output power of 1.1 W at 4.5 m and of more than 3 W at 3 m were achieved for 6-ps-long pulses with a repetition rate of 160 MHz and an M2 < 2.