Saturation processes in a cw dye laser under combined mode locking conditions

Analytic relationships are derived between modulated values of the gain and absorption, on the one hand, and the energy density of a pulse in an amplifier governing the duration of the output pulses, on the other. The results obtained are interpreted. The main reason for the restrictions on the duration of the pulses in the case of purely synchronous pumping is identified: it is the excess residual gain exceeding the resonator losses. This shortcoming can be overcome by the use of a saturable absorber. This approach has made it possible to shorten the duration from 800 fsec in the case of purely synchronous pumping to 300 fsec for a combined method without intracavity compression.