Simultaneous amplification and compression of picosecond pulses to 50 kW in Er fiber

We describe a simple erbium fiber based master oscillator power amplifier generating record 50 kW peak power in a diffraction and bandwidth limited pulse. The fiber oscillator uses carbon nanotubes for saturable absorption and modelocking. It is followed by a single mode Er fiber amplifier. Nonlinear Schrodinger equation (NLSE) simulations ignoring gain confirm that interaction between self phase modulation and anomalous dispersion at these intensities leads to simultaneous spectral broadening and temporal compression to close to bandwidth limit. At higher nonlinearities, spectral modulations and pulse breakup occur experimentally and numerically.