Kerr-lens Mode Locking Without Nonlinear Astigmatism

TL;DR

This paper introduces a novel Kerr-lens mode locking technique using a planar Ti:sapphire crystal in a folded cavity to eliminate nonlinear astigmatism, simplifying laser design and improving performance.

Contribution

It presents a new cavity folding method that cancels nonlinear astigmatism without the need for power-specific compensation, using a planar-cut gain medium.

Findings

Achieved Kerr-lens mode locking with a planar Ti:sapphire crystal.

Demonstrated cancellation of nonlinear astigmatism in the cavity.

Validated the method's effectiveness in a folded cavity configuration.

Abstract

We demonstrate a Kerr-lens mode locked folded cavity using a planar (non-Brewster) Ti:sapphire crystal as a gain and Kerr medium, thus cancelling the nonlinear astigmatism caused by a Brewster cut Kerr medium. Our method uses a novel cavity folding in which the intra-cavity laser beam propagates in two perpendicular planes such that the astigmatism of one mirror is compensated by the other mirror, enabling the introduction of an astigmatic free, planar-cut gain medium. We demonstrate that this configuration is inherently free of nonlinear astigmatism, which in standard cavity folding needs a special power specific compensation.