Coherent beam combination of two slab laser amplifiers based on stochastic parallel gradient descent algorithm

Abstract

Coherent beam combination (CBC) of laser arrays is an efficient way to scale brightness. We demonstrate CBC of two slab laser amplifiers based on active phase locking. Instead of the complex phase detection system, intensity detection is used and the feedback control signal is calculated based on the stochastic parallel gradient descent (SPGD) algorithm. The experimental investigation on a 101.5-W CBC of two slab amplifiers shows that the entire system in a closed loop performs well for long-time observation. A combination efficiency of nearly 81% is realized. The slab amplifier laser arrays are the coherent beams efficiently combined by active phase locking based on the SPGD.

Coherent optical link phase noise control based on SPGD algorithm with optimal estimation

“…In the field of coherent beam combination [1][2][3][4] , due to the non-idealities and noise of optical systems, phase distortions can occur, which can affect the quality of the beam. By introducing the SPGD algorithm, the influence of phase distortions can be eliminated and the beam quality can be improved.…”

Hybrid approach used for extended image-based wavefront sensor-less adaptive optics

“…The control algorithms in WSAO can be divided into two categories: model-free algorithms and modal-based algorithms. Model-free algorithms like hill climbing [1] , genetics [2] , and stochastic parallel gradient descent (SPGD) [3] have been widely used in many scenarios. Their common disadvantages are that a large number of iterations are usually needed and a global convergence is not always guaranteed.…”