Yb-Fiber-Laser-Pumped Ultrafast Frequency Conversion Sources From the Mid-Infrared to the Ultraviolet

We describe the development of versatile, practical, and high-power ultrafast optical sources based on second-order nonlinear frequency conversion in bulk materials pumped by the mode-locked Yb-fiber laser at 1064 nm, and covering spectral regions from the near- to mid-infrared (mid-IR) to the visible and ultraviolet (UV). By exploiting synchronously-pumped optical parametric oscillators (SPOPOs) based on quasi-phase-matched nonlinear materials of MgO:PPLN and MgO:sPPLT, in combination with internal and external single-pass harmonic generation in birefringent crystals of BiB₃O₆ and β-BaB₂O₄, we have generated tunable picosecond pulses in spectral regions from above ~4 μm in the mid-IR, into the visible, and down to 317 nm in the UV. The demonstrated sources can deliver average output powers of up to 11.7 W in the near- to mid-IR, 3.5 W in the visible, and 30 mW in the UV, in picosecond pulses at ~80 MHz repetition rate, with high passive stability, excellent output characteristics, and the potential for further power scaling with increased fiber laser pump power. The described sources represent an effective approach for the extension of fiber laser technology across the entire wavelength range from the UV to mid-IR spectrum, and ultimately the THz spectral range.