Experimental and theoretical investigations of the influence of a saturation grating in an absorber on pulse generation in a passively mode-locked dye laser

The influence of a saturation grating in the absorber of a passively mode-locked dye ring laser in the colliding pulse mode locking (CPM) regime on the pulse parameters is calculated and experimental results are presented. By changing from a Fabry–Perot resonator without a saturation grating in the absorber to a ring resonator in the CPM regime operating under similar experimental conditions, the pulse durations can be reduced from 0.4 to 0.1 psec. As a result of coherent interaction, approximately threefold reductions in the pulse duration and significantly broader regions of stability are obtained theoretically. If the active medium is shifted from its symmetrical position for equal amplification of the opposite (counterpropagating) pulses, numerical calculations give pulses having different energies and smaller regions of stability. Experimental results are reported.