108 kW, 26 times diffraction limited laser based on a continuous wave Nd:YAG oscillator and an extra-cavity adaptive optics system

In this Letter, a 10.8 kW, 2.6 times diffraction limited laser based on a continuous wave (CW) Nd:YAG oscillator using an unstable resonator and an extra-cavity adaptive optics system was presented. Two Nd:YAG slabs and a disk-laser configuration were used to make the laser compact and power scalable. The output was a rectangular annulus, which was further expanded to a square annulus and was adaptively corrected by an extra-cavity deformable mirror (DM). The DM was designed to be capable of correcting the square annular wavefront aberrations. In the experiment, the vertical beam quality was improved from 51.7 to 2.6 times diffraction limited after correction. To the best of our knowledge, this is the highest power and brightness based on a CW Nd:YAG oscillator.