Laser-controlled adaptive optics for beam quality improvements in a multi-pass thin-disk amplifier.

We devise a laser-controlled adaptive optical element that operates intracavity under high-intensity radiation. This element substitutes a conventional mechanically deformable mirror and is free of critical heat-sensitive components and electronics. The deformation mechanism is based on the projection of a continuous-wave control laser onto a specially designed mirror. Mounted to a water-cooled heat sink, the mirror can handle laser radiation beyond 3  MW/cm. The properties of the adaptive optical element, including the maximum correctable wavefront pitch of 800 nm, are discussed. The successful implementation in a multi-pass thin-disk amplifier is presented. An improvement of the beam quality by a factor of three is achieved. We identify measures to enhance the performance of the adaptive optics towards efficient operation in a high-power laser system.