Independently tunable 13 W femtosecond Ti:sapphire lasers passively synchronized with attosecond timing jitter and ultrahigh robustness

A stable passively synchronized femtosecond laser has been realized by coupling two 1.3 W mode-locked Ti:sapphire lasers with a Kerr medium. An ultralong tolerance of 10 microm for the cavity length mismatch and a timing jitter of less than 0.4 fs were obtained. The relative carrier-envelope phase slip was directly observed by measuring the heterodyne output between the two lasers.