Kinetics of a dye laser with dynamic distributed feedback and travelling-wave pumping

A numerical investigation is reported of the kinetics of a dye laser with dynamic distributed feedback (DFB) and pumped by a travelling wave. The use of picosecond ‘skew’ pump pulses (pulses with noncoincident amplitude and phase fronts) makes it possible to generate single ultrashort pulses of duration less than the travel time of the radiation in the active medium. Such output pulse compression is due to conservation of the spatial positions of lines in a dynamic grating responsible for the DFB effect when the intensity envelope of a skew pump pulse travels along the active medium (travelling-wave pumping). It is shown that the minimum duration of an output pulse, propagating parallel to a travelling pump wave, and its highest peak intensity are reached when the velocities of the pump and output waves are ‘synchronised’.