Tm-Doped Nonlinear Fiber Amplifier Emitting 50 fs Pulses and 20 W of Average Power at 2 μm Wavelength

Thulium-doped fiber lasers with an emission wavelength around 2 μm have drawn increasing attention for applications in fundamental and life sciences [1, 2]. It has recently been identified, that the utilization of long wavelength drivers is beneficial for the parametric downconversion into the molecular fingerprint region (2-20 μm wavelength), since they can effectively use conveniently available non-oxide crystals with high conversion efficiency to address the wavelength region beyond 5 μm, which is difficult with today's well matured 1 μm drivers [3, 4]. Transferring these results into an application driven context in medical and life sciences requires a compact design and flexibility of the driving source to serve a huge audience. Addressing the mid infrared fingerprint region via parametric downconversion requires both, short pulses and moderate peak power to ensure a good spectral coverage. To fulfill these requirements chirped pulse amplifiers use bulky post compression schemes, which makes them not well suited for this field of application. In this work we propose a nonlinear fiber amplifier, which has the potential to drastically shrink the footprint of the driving source, by combining both compression and amplification in a single fiber. This will ultimately enable for high-power shoebox size laser sources in the molecular fingerprint region.