Simultaneous generation of 5.87 W average and 0.75 MW peak power at 3.1 µm from a single pass, single stage parametric source

In an optical parametric source, a well-designed tightly focused pump beam is almost regarded as the sole choice, since it can significantly lower the pump threshold and enhance the conversion efficiency. However, this does not mean that the highest power is enabled simultaneously for an identical nonlinear crystal. In this paper, we attempt to engineer the pump beam in different regimes to explore the ultimate performance of optical parametric generation (OPG) by using MgO: PPLN crystal. It is verified that, comparatively, the best pump regime is to smooth the beam evolution through the crystal longitudinally and meanwhile enlarge the beam size transversally. This is equivalently to more fully utilize the effective aperture throughout the crystal and consequently enhance the crystal's capability in power tolerance. Although such a regime might be feasible logically, it has never been explored for OPG. By it, the signal and idler average/peak powers reached ∼10.45 W/∼1.39 MW and ∼5.87 W/∼0.75 MW at corresponding wavelengths of ∼1624.7 nm and ∼3107.8 nm, respectively, representing both the highest average and peak power levels at MHz repetition rate by using OPG, to the best of our knowledge. This superior performance, added to the other unique properties of OPG, offers a simplified, efficient, and robust solution in enabling simultaneously high average and high peak power mid-IR ultrashort pulses.