Active beam cleanup of pulsed slab laser based on 59-unit adaptive optics system

Abstract

Beam quality is one of the key technical targets in the high-power laser system, and it can be dramatically improved by using adaptive optics. In this paper, a research on the near field distribution of the pulsed slab laser has been carried out. A Shack Hartmann wavefront sensor was used to measure the aberrations, and the wavefront reconstruction was accomplished afterwards. Because of the special near field distribution, the diffraction limited factor β has been revised for better describing beam quality. The theory model of the correction of aberrations with deformable mirror (DM) was introduced. Based on the theory model, the numerical analysis of the correction ability of DM with 59 actuators and correction of measured wavefront have been carried out, the result showed that the peak value of far field was improved 3.2 times, and the beam quality was increased 3 times. An experimental setup for beam cleanup of pulsed laser has been established. A demonstrated experiment was carried out on this platform. The result of the experiment indicated that the output beam quality of the pulsed slab laser can be validly improved by beam cleanup using adaptive optics system with 59-actuator DM. Specifically, the peak value of far field has been raised by 3 times, and the factor β has been increased by 3 times as well, which was mostly in accordance with the numerical analysis. The conclusion of this paper offered reference for the achievement of near diffraction limited beam quality in the future.