A new technique is suggested for the generation of laser beams with an intensity profile specified. The technique is based on the coherent combining of radiation of a fiber laser array with adaptive control of the power and phase of Gaussian subbeams with plane wavefronts. The power and phase of the subbeams are determined for each intensity profile specified in the far field based on the inverse problem solution, for example, by the Gershberg–Saxton method. To form a required phase profile, the stochastic parallel gradient descent (SPGD) method is used along with the inversion of a required phase distribution with a phase corrector. The main advantages of the technique are the adaptive control of the intensity profile and a possibility of generating high-power laser beams. The results of numerical and field experiments are described.
The problem of information transmission by modulating the topological charge of the orbital angular momentum (OAM) of beams synthesized by an array of fiber lasers during radiation propagation through a turbulent atmosphere is investigated. The possibility of adaptive compensation for turbulent distortions of a beam in the periodic process of successive phase matching in the receiver plane and phase modulation in the initial radiation plane for information transmission is demonstrated for the first time. A mathematical model of the process of adaptive control for two modifications of the feedback loop and the results of OAM recognition by machine learning methods are presented.
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