Megawatt solitons generated above 2000 nm in Bragg fibers

Abstract

Solitonic effects, including multi-solitonic fission and subsequent self-frequency shift, are used to tailor ultrashort (sub-100 fs) pulses with carrier wavelength broadly tunable in spectral regions between fixed laser lines. Although high-energy pulses can be obtained in stiff waveguides, the benefit of pulse delivery through bends is lost. Here, we report on the generation, sustained propagation, and large frequency shift of megawatt-class pulses in all-silica antiresonant fibers with ultra-large mode area. We designed and fabricated a flexible fiber with a 2710 μm2 effective mode area and a 10 cm critical bend radius. When pumped by a sub-picosecond thulium-doped fiber-based chirped pulse amplifier, the fiber delivers 90 fs pulses at 2220 nm with a 2.8 MW peak power. The system might be used to drive high-order harmonic generation in solids.