Square nanosecond Yb- And Er-doped fiber lasers passively synchronized to a Ti:sapphire laser based on cross-absorption modulation

Robust synchronization was achieved for Ti:sapphire, Yb- and Er-doped fiber mode-locked lasers in a master-slave configuration. Square nanosecond pulses were generated in the long-cavity fiber lasers, while synchronization was maintained owing to resonance-enhanced cross-absorption modulation in an additional Er-doped fiber, allowing for a cavity mismatch tolerance of 8.2 and 3.6 cm, respectively. This is the highest tolerable cavity-length difference ever obtained for synchronized mode-locked lasers.