Fiber-laser-based, green-pumped, picosecond optical parametric oscillator using fan-out grating PPKTP.

Abstract

We report a stable, Yb-fiber-laser-based, green-pumped, picosecond optical parametric oscillator (OPO) for the near-infrared based on periodically poled potassium titanyl phosphate (PPKTP) nonlinear crystal, using fan-out grating design and operating near room temperature. The OPO is continuously tunable across 726-955nm in the signal and 1201-1998nm in the idler, resulting in a total signal plus idler wavelength coverage of 1026nm by grating tuning at a fixed temperature. The device generates up to 580mW of average power in the signal at 765nm and 300mW in the idler at 1338nm, with an overall extraction efficiency of up to 52% and a pump depletion >76%. The extracted signal at 765nm and idler at 1746nm exhibit excellent passive power stability better than 0.5% and 0.8% rms, respectively, over 1h with good beam quality in TEM00 mode profile. The output signal pulses have a Gaussian temporal duration of 13.2ps, with a FWHM spectral bandwidth of 3.4nm at 79.5MHz repetition rate. Power scaling limitations of the OPO due to the material properties of PPKTP are studied.