Dynamics of emission from dye lasers employing synchronous pumping by limited picosecond pulse train

Synchronous pulsed emission of organic dye lasers pumped by a train of picosecond pulses from a mode-locked laser is examined theoretically and experimentally. A model is developed for the production of supershort light pulses. A four-level model of the active medium is employed, making it possible to investigate the mode-locking kinetics and to calculate the limiting emission parameters. Because the synchronous emission process is unsteady, it is found that the parameters in the pulse train change significantly, and that there is no complete time correlation between an emitted pulse and its corresponding pumping pulse. It is recommended that trains containing more than thirty pulses be employed in order to obtain synchronously tracking pulses with minimum duration, and that the length of the dye laser cavity be adjusted to obtain the maximum second-harmonic radiation energy in order to produce the shortest possible pulses. The experimental findings agree well with the theory; the minimum spectrally-limited pulse length achieved is 8 ps.