Single and double mode-locked ring dye lasers - Theory and experiment

A computer model is made of the colliding-pulse ring dye laser for mode-locked production of short pulses. Initial conditions of either noise or a small CW oscillation eventually result in the same final solution. Resolution is 10 ps in the model, and a digital filter represents dispersion. A gain-sharing long pulse mode often results, but large effective absorption cross section in the mode-locking dye and optimum separation of the two dyes (one quarter of the total resonator length) favor the desired short pulse formation. The model does not include the transient grating effect. Experiments with a ring laser using rhodamine 6G and DODCI confirmed the parameters important to the two regions. Double mode locking, in which the mode-locking dye also lases, was also studied both in the model and experimentally. It is not yet clear if the advantages of colliding pulse mode locking apply to double mode locking.