Binding widely-separated pulses with a passively mode-locked Yb-doped double-clad fiber laser

We have investigated the generation of widely-separated bound pulses with a high power passively mode-locked Yb-doped double clad fiber laser. We report on the emission of bound pulses of 5 ps whose separation can exceed 180 ps. Pulses are further compressed extra-cavity to 140 fs, leading to pulse separations that can reach approximately 1300 pulse widths, while pulses remain bound. Scenarios leading to these regimes are detailed. RF analysis shows an important reduction of the amplitude noise of the laser when pulses bind together. Finally, we report on a new regime of multiple pulse emission of this fiber laser: stable co-emission of a single-pulse and a pair of bound pulses in the same cavity round trip.