ABSORBER-ASSISTED KERR-LENS MODE-LOCKING

We study mode locking of a titanium-doped sapphire laser with a slow s aturable absorber in the cavity. We show that the presence of the abso rber stabilizes the pulsed mode of laser operation over a broader rang e of cavity mirror position and for a wider aperture. However, the bas ic principle of operation is unchanged from that of a conventional Ker r-lens mode-locked laser, in that, in all cases, we observed strong sp ace-time focusing of the pulses into the laser crystal. Thus the absor ber cannot lead to shortening of the pulse below the limit imposed by the Kerr-lens mode locking. (C) 1998 Optical Society of America [S0740 -3224(98)01619-5].