Generation of sub-60 fs pulses from an Yb-doped fiber amplifier by direct compression with the use of a Dazzler
Résumé
In this work we investigate the potentiality of the combined operation of a large-mode area (LMA) double-clad Yb-doped fiber amplifier with such an active phase and amplitude shaper (Dazzler, Fastlite). In contrast with pure parabolic amplification, the pulses are amplified and both temporally and spectrally broadened in an unconventional nonlinear regime dominated by self phase modulation (SPM), in the presence of gain and positive dispersion. In this setup, the Dazzler is placed directly after the amplifier and simply used as a compressor, alternatively to a conventional 1250-line/mm transmission-grating compressor. Our purpose was to investigate the ability of the Dazzler to compensate the complicated spectral phase components of the amplified pulses and therefore its potentiality as an intermediate active element of a future more complex CPA system. The generation of high quality 56 fs, 230 nJ pulses at 20 kHz is demonstrated.