Saturation of Kerr-lens mode locking and the self-amplitude modulation coefficient

摘要

This work deals with the saturation of the Kerr-lens mode locking mechanism. A quantitative description of the self-amplitude modulation effect in a laser cavity is derived, considering both the nonlinear and geometrical (cavity) contributions to this nonlinear modulation. The loss of the pulse conformation strength in a cavity due to "bleaching" of the fast saturable absorber behavior of the Kerr lens together with an intracavity aperture produces the appearance of instabilities. The goal is then to elaborate a formalism that allows the prediction of these instabilities, and develops as useful for short pulse laser cavity design in general. The obtained self-amplitude coefficient is included within the KIJL ray-pulse matrix formalism, and a simple model for the temporal pulse parameters regarding only the amplifier bandwidth and the self amplitude modulation is studied. This model sets a limit for the maximum pulse energy of a stable solution for a given nonlinear modulation and bandwidth.