Efficiency of single-mode thin-disk lasers

Thin-disk lasers have a weak thermal lens and they have a high efficiency in multi-mode operation. However, the residual higher-order thermo-optical aberrations limit their efficiency in single mode operation. The reason is that these thermo-optical aberrations cause diffraction losses for the TEM₀₀ mode. To further increase the efficiency of fundamental mode thin-disk lasers, we want to compensate for the aberrations by means of a newly developed deformable mirror. The mirror layout has to be adapted to the aberrations, which requires their precise knowledge. Therefore, we carried out interferometric measurements of the thermo-optical aberrations of the gain medium. Furthermore, we characterized resonators with different TEM₀₀ spot sizes in order to understand how the aberrations affect the output power and beam quality.