High average power 200 fs mid-infrared KTP optical parametric oscillator tunable from 2.61 to 3.84 μm

We report a broadly tunable mid-infrared femtosecond KTiOPO 4 optical parametric oscillator (OPO) pumped by a mode-locked Yb:KGW oscillator. Under pump power of 7 W, up to 2.05 W average power was generated in the 1.41–1.71 μm region at a repetition rate of 151 MHz, corresponding to a pump-to-signal conversion efficiency of 29.3%. After compensating the intracavity dispersion, the pulse width of the signal wave was measured to be 200 fs at 1.6 μm, close to the transform-limited pulse duration. For the idler pulse, during the tuning range from 2.61 to 3.84 μm, the average powers were greater than 1 W, with a passive stability better than 0.7% rms during 3 h.