Generation of tunable picosecond pulses by pulse stacking in an Yb-fiber gain-assisted pulse stacker.

We report on the generation of tunable picosecond pulses of high repetition rate by pulse stacking in an Yb-fiber stacker that benefited from high optical gain, properly time delay and laser synchronization. The gain-assisted pulse stacker could be controlled for pulse shaping to produce tunable pulse duration from ps to sub-ns range by managing the intracavity dispersion and adjusting the time delay. The energy loss during the pulse shaping process was compensated by the gain of a 60-cm-long Yb-fiber pumped by a diode laser. The temporal profiles of the output pulses were measured by using a special cross-correlation technique. The duration of the stacked pulses could be tuned from 5 to 200 ps with a controllable time interval.