Yb-Fiber-Laser-Pumped Continuous-Wave Frequency Conversion Sources from the Mid-Infrared to the Ultraviolet

We describe a wide range of versatile, practical and high-power sources of coherent continuous-wave (cw) radiation from the near- to mid-infrared (mid-IR) to the visible and ultraviolet (UV) developed in our laboratory by exploiting second-order nonlinear frequency conversion in novel quasi-phase-matched (QPM) and birefringent materials pumped by the Yb-fiber laser at 1064 nm. By exploiting optical parametric oscillators in combination with internal and external single-pass harmonic generation in QPM nonlinear materials of MgO:PPLN and MgO:sPPLT, and birefriengent crystal of BiB₃O₆, we have generated stable, high-power cw radiation covering broad spectral regions from ~4 μm in the mid-IR, to 532 nm in the visible, down to 355 nm in the UV. The developed sources can deliver total output powers of up to 17.5 W in the near- to mid-IR, 13 W in the visible, and 68 mW in the UV, at exceptional efficiencies, with excellent passive stability, high spectral and spatial beam quality, in compact, portable and practical design. We also demonstrate successful realization of cw fiber-laser-pumped Ti:sapphire lasers enabled by the development of simplified high-power cw green sources at 532 nm. The described techniques represent a highly versatile, practical, and effective approach for the extension of fiber laser technology across the entire UV to mid-IR spectrum, and ultimately the THz spectral range, also offering the potential for further power scaling with the increase in the fiber laser pump power.