Watt-level widely tunable femtosecond mid-infrared KTiOAsO optical parametric oscillator pumped by a 1.03 μm Yb:KGW laser.

A high-power, high-repetition-rate, broadband tunable femtosecond optical parametric oscillator (OPO) is constructed based on KTiOAsO crystal, pumped by a 75.5 MHz mode-locked Yb:KGW laser. With 7 W pump power, the OPO generates as much as 2.32 W of signal power at 1.55 μm and 1.31 W of idler power at 3.05 μm, corresponding to a total conversion efficiency of 51.8%. Operating at 151 MHz repetition rate, the wavelength of the signal covers 1.41-1.71 μm with a tunable idler range of 2.61-3.84 μm. The idler bandwidth is more than 180 nm over the entire mid-infrared range. By compensating intracavity dispersion, the signal pulse has a nearly Fourier transform-limited duration of 129 fs at 1.52 μm.