COMPLETELY SELF-STARTING PICOSECOND AND FEMTOSECOND KERR-LENS MODE-LOCKED TI-SAPPHIRE LASER

Completely self-starting and stable operation of a Kerr-lens mode-lock ed Ti:sapphire laser was realized in both picosecond and femtosecond r egimes. The cavity has a symmetric X configuration with soft aperturin g. Enhanced Kerr nonlinearity and reduced backscattering effects were thought to be key to obtaining stable self-starting self-mode-locked o peration from 765 to 815 nm far the picosecond regime and from 770 to 835 nm for the femtosecond regime. The mode-locking starting time as m easured by the onset of the second-harmonic signal ranged from 300 ms to 2 s, depending on cavity alignment. Preliminary data also suggest t hat intracavity intensity fluctuation necessary for the laser to evolv e into stable mode locking could be as short as 10-40 ps.