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Effects of Gaussian Beam Combining Through Non-Kolmogorov Turbulence
G. Yang, L. Liu, Z. Jiang, T. Wang and J. Guo

Beam combining is one of the most promising technologies available to achieve high energy laser output. This paper elucidates the incoherent beam combining (ICBC) system using the scholastic parallel gradient descent (SPGD) algorithm for the correction of laser beam pointing during the combining process. It has been verified that the Kolmogorov model is not accurate enough in describing the actual turbulence. This situation has stimulated the development of the non-Kolmogorov turbulence theory. Much of the research has focused on the laser beam propagating through non-Kolmogorov turbulence. Herein a system for incoherent laser beam combining is proposed. The effects on the laser beam combining that induced by the non-Kolmogorov turbulence are theoretically analysed. The extended Huygens-Fresnel theory is used to calculate the results of the laser beam propagating through atmospheric turbulence. The influence of the power law exponent of non-Kolmogorov power spectrum is discussed in detail, with the simulation of incoherent beam combining of six laser beams through non-Kolmogorov turbulence being carried out. The SPGD algorithm is employed for the correction of laser beam pointing through non-Kolmogorov turbulence. The simulation results show that the proposed system is feasible under the situation of non-Kolmogorov turbulence.

Keywords: Laser beam, incoherent beam combining, non-Kolmogorov turbulence, incoherent beam combining (ICBC) system, scholastic parallel gradient descent (SPGD) algorithm, power law exponent

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