Combined mode locking in a cw rhodamine 6G laser using triphenylmethane dyes

An experimental study was made of the characteristics of the radiation emitted by a synchronously pumped dye laser utilizing a mixture of rhodamine 6G with crystal violet or malachite green. The pulse duration of 700 fsec was limited by the pass band of a tunable filter. The wavelength tuning range was governed by the condition σ_ab(λ)/σ_am(λ)>1, where σ_ab and σ_am are the absorption and amplification cross sections. Introduction of an absorber into the jet of the rhodamine 6G solution increased the permissible mismatch between the resonator lengths from a few microns (for pure rhodamine 6G) to a fraction of a millimeter and improves drastically the stability of the radiation characteristics.