Adaptive optics for solid state lasers

The availability of low-cost deformable mirrors with high damage-threshold has made active compensation of aberrations in solid state lasers possible. A master-oscillator-power-amplifier (MOPA) system with adaptive aberration correction has been developed. This type of aberration can´t be compensated with an adaptive mirror but can be compensated with the use of two identical laser rods that are relay imaged onto each other and a 90° quartz rotator placed between the rods. For a practical aberration-correction scheme a simple and robust feedback system for the adaptive mirror is desirable. Measuring the aberrations during laser operation with the required precision to drive the adaptive mirror would be an extremely difficult task. It is much simpler and more robust to measure the beam quality of the generated or amplified beam itself and derive the feedback signal from this measurement. The output power will rise considerably when the amplifiers are double-passed and saturation is achieved. At the conference we will present out latest results for optimized adaptive MOPA systems. In addition to the experimental results we will present theoretical results on the required wavefront fidelity in a closed-loop adaptive resonator for TEM₀₀-operation.