Widely tunable optical parametric oscillator based on four-wave mixing

For the first time, a broadly tunable, synchronously pumped optical parametric oscillator (OPO) based on four-wave mixing (FWM) is demonstrated. The setup generates signal wavelengths between 800 and 975nm and idler wavelengths between 1125 and 1420 nm. The FWM OPO cavity is pumped with a tunable Yb-based master oscillator power amplifier delivering 43 ps long pulses with wavelengths between 1025-1065nm. The cavity has a resonance frequency of 780 kHz, enabling high pulse energies at moderate average power levels. The signal and idler pulses exit the cavity with a linear chip and bandwidths of up to 6.5 nm. By employing dielectric gratings, we were able to compress the out-coupled pulses down to 560 fs at 1250 nm. This source provides a fiber based alternative to expensive and bulky OPO based on birefringent crystals and should find numerous applications e.g. in non-linear imaging and life science.