Continuous-wave versus pulse regime in a passively mode-locked laser with a fast saturable absorber

The phenomenon of modulation instability of continuous-wave (cw) solutions of the cubic–quintic complex Ginzburg–Landau equation is studied. It is shown that low-amplitude cw solutions are always unstable. For higher-amplitude cw solutions, there are regions of stability and regions where the cw solutions are modulationally unstable. It is found that there is an indirect relation between the stability of the soliton solutions and the modulation instability of the higher-amplitude cw solutions. However, there is no one-to-one correspondence between the two. We show that the evolution of modulationally unstable cw’s depends on the system parameters. © 2002 Optical Society of America OCIS codes: 190.5530, 190.5940, 140.3510, 320.5540.