MECHANISM FOR SELF-SYNCHRONIZATION OF FEMTOSECOND PULSES IN A 2-COLORTI-SAPPHIRE LASER

An experimental and theoretical analysis of the nonlinear coupling mec hanism between the two solitary pulses circulating in a two-color femt osecond laser is presented. Two operation regimes-synchronized and non synchronized--and a hysteresis of the transition between the two regim es are clearly observed, while independent modelocking and tunability of the output pulse trains is found in both regimes. Pulses in the ran ge from 15 to 100 fs are synchronized with a timing jitter below 2 fs. The combined effects of cross-phase modulation and negative group vel ocity dispersion are shown to be responsible for the strong pulse corr elation in the synchronized regime. Our experimental observations are in agreement with numerical simulations, thus confirming the theoretic al model.