High-power solid-state lasers with good beam quality are of interest for many industrial applications, e.g. material processing. The better the beam quality of the laser, the smaller is the focal spot of a lens. Thus high intensities require high laser output powers and good beam quality. The quality of a laser beam is limited by aberrations of the gain medium. During pumping, it is unavoidable to heat the laser crystal. Temperature gradients in the crystal then cause an aberrated thermal lens. These aberrations not only lead to a degradation of beam quality, but also to high diffraction losses and therefore limit the output power of the laser. Calculations and simulations have shown that a reduction of thermo-optical aberrations drastically improves the laser performance.
In this project, we develop and test concepts of laser resonators where an intracavity adaptive mirror compensates for the troublesome thermo-optical aberrations. Control of the adaptive mirror is achieved by means of a genetic algorithm.