Bifurcation of fundamental Gaussian modes in Kerr-lens mode-locked lasers

We propose that more than one spatial fundamental Gaussian mode may occur i n concentric and confocal resonators under persisting nonlinear effect. Ext ensively studying the influence of the resonator's parameters in a Kerr-len s mode-locked resonator, pitchfork bifurcation results in more symmetrical configurations, and saddle-node bifurcation appears as the symmetry being b roken. From the properties of bifurcation, we suggest that the equal-arm an d near-confocal resonator is suitable for the emergence of bistability in K err-lens mode-locked lasers. (C) 1999 Elsevier Science B.V. All rights rese rved.