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Measurements of the self-starting threshold of Kerr-lens mode-locking lasers.

We measured the self-starting threshold of passive Kerr-lens mode-locking dye lasers and Ti:sapphire lasers by varying the concentration of the intracavity dilute-dye saturable absorbers that start the mode locking. From the threshold absorber concentration, we determined the strength of the intracavity pulse-broadening effects that counteract the pulse-shortening mechanisms in the self-starting stage. Experimental results agree well with theories based on phase diffusion and mode pulling.