| Summary: | We demonstrate the damage-free delivery of nearly diffraction-limited picosecond laser pulses at 1064 nm with a maximum peak power of 3.5 MW in a 5 m air-filled anti-resonant hollow-core fiber (AR-HCF). In the air-filled AR-HCF, the transmission efficiency of picosecond pulses is degraded due to stimulated Raman scattering for the incident peak power above 3.59 MW. The temporal compression of pulses is also observed in the air-filled AR-HCF, where the self-phase modulation plays a key role in the anomalous dispersion region. By vacuuming the air in the core, a nearly constant coupling efficiency of 77% is achieved through the 5 m AR-HCF free of nonlinear effects, with M<sup>2</sup> of the output beam less than 1.17.
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