Abstract

There has been much recent interest in using a nonlinear lensing element combined with an aperture to produce a saturable absorber for laser modelocking. [1, 2] This Kerr-lens-modelocking (KLM) technique normally uses the gain medium as the nonlinear element, but lasers with separate gain and nonlinear elements have also been demonstrated,[3] allowing application of this method to lasers in which the gain medium does not provide adequate self-focusing or gain-guiding. The analysis we have carried out seems to indicate that the nonlinear element need not be self-focusing; in fact, it appears that a larger effect can be obtained by a self-defocusing element. Additionally, in the ring resonator geometry we consider, the intensity-dependent lensing leads naturally to unidirectional propagation for continuous-wave lasing.

© 1992 Optical Society of America