Near diffraction-limit beam quality of solid-state slab
 lasers achieved with adaptive optics

Solid-state lasers have been extensively used in industrial, medical and research applications for their compactness, light weight, long life and high efficiency. Traditional solid-state rod lasers suffer from severe thermally induced birefringence and thermal lensing under high power pumping, which make it difficult to obtain high beam quality and high output power simultaneously. To alleviate these thermal effects, Martin etc. proposed solid-state slab lasers in 1969. However, wavefront distortions can still be observed in solid-state slab lasers due to thermal effects, leading to deteriorated beam qualities. How to achieve high average output power with perfect beam quality remains a major concern in the development of solid-state slab lasers.
    Prof. Bing Xu’s team from Key Laboratory of Adaptive Optics, Institute of Optics and Electronics, Chinese Academy of Sciences have been engaged in beam cleanup of solid-state slab lasers with adaptive optics. Solid-state slab lasers specifically demand large-amplitude low-order aberration compensations of laser beams with high aspect ratio, advanced manipulations of large local phase gradients, and extra flexible real-time wavefront controllers, which is different from conventional applications of adaptive optics systems. Prof. Xu’s team has successfully developed low-order aberration compensators based on geometric optics, weighted least-square wavefront reconstruction algorithm, and generic real-time wavefront processors implemented with x86 CPUs and real-time operating systems. Based on these techniques and components, a hybrid adaptive optics system was integrated into the 5J/200Hz/6.6ns high power nanosecond laser system developed by Academy of Opto-electronics, Chinese Academy of Sciences, and beam quality of 1.64 times of diffraction-limit was achieved. About two dozens of adaptive optics systems have been delivered to a variety of slab laser systems in China so far. With effective operations of these adaptive optics systems, the beam qualities of the laser systems have all been well improved. 

Far-field intensity distribution of the beam after corrected by the 59-actuator deformable mirror

About team
The solid-state laser beam cleanup team from Key Laboratory of Adaptive Optics, Institute of Optics and Electronics, Chinese Academy of Sciences develops key components, techniques and adaptive optics systems for beam cleanup of solid-state lasers, manipulations of laser resonators, and beam combination. This team is consisted of Profs. Bing Xu, Ping Yang, Guomao Tang, Associate Profs. Shanqiu Chen, Lizhi Dong, Wenjin Liu, Yi Tan, Shuai Wang, Drs. Xing He, Boheng Lai, and Xin Yu. They have published nearly a hundred research papers, been granted over two dozen of patents, won a National Science and Technology Progress Award and three ministerial Science and Technology Progress Awards.

Dong L Z, Xu B, Yang P, et al. Recent progress of adaptive beam cleanup of solid-state slab lasers in Institute of Optics and Electronics, Chinese Academy of Sciences[J]. Opto-Electronic Engineering, 2018, 45(3): 170539.