Femtosecond mid-IR difference-frequency generation in BaGa2GeSe6 from a 40 MHz optical parametric oscillator pumped at 1035 nm

Mixing the signal and idler pulses near 2 µm from a femtosecond synchronously-pumped optical parametric oscillator in a BaGa2GeSe6 crystal we generate mid-IR pulses tunable up to 10 µm with 45% maximum internal quantum efficiency.