High peak-power mid-infrared ZnGeP2 optical parametric oscillator pumped by a Tm:fiber master oscillator power amplifier system

We report on the utilization of a novel Tm:fiber laser source for mid-IR ZnGeP2 (ZGP) optical parametric oscillator (OPO) pumping. The pump laser is built in a master oscillator power-amplifier configuration delivering up to 3.36 W of polarized, diffraction limited output power with 7 ns pulse duration and 4 kHz repetition rate. This corresponds to a peak power of similar to 121 kW and a pulse energy of similar to 0.84 mJ. With this source, we generated 27.9 kW of total mid-IR peak power in a doubly resonant oscillator (DRO) configuration. This is, to the best of our knowledge, the highest ever demonstrated mid-IR peak power from a directly Tm: fiber laser pumped ZGP OPO. Moreover, a DRO output with about 284 mu J of total mid-IR pulse energy was demonstrated using 100 ns pump pulses. The wavelength tuning of the idler was extended to 6 mu m with lower output power in another OPO experiment. (C) 2014 Optical Society of America