We show that a soliton of the nonlinear Schrodinger equation perturbed
by filter losses and/or the finite gain bandwidth of amplifiers can b
e kept stable by saturable absorbers with a relaxation time much longe
r than the width of the soliton. This provides for ultrashort pulse ge
neration with a slow saturable absorber only and may have possible app
lications in the stabilization of soliton storage rings.