Atmospheric turbulence has severe influence on laser beam propagations. The well accepted method of compensating for the aberrations in the turbulence is generating a beacon on the target or at the point-ahead location. In most scenarios, the wavelength of the beacon is similar to or shorter than the launched beam. However, when the strength of the turbulence gets stronger, intensity scintillations and wavefront branch points also arise, making it difficult to accurately measure the wavefront. As scintillations and branch points weakens with wavelength increases, it is reasonable to consider using beacons with longer wavelengths to improve wavefront detection accuracy. To further investigate the feasibility of beacons with longer wavelengths, we established a simulation model of wavefront detection and correction in horizontal path under strong turbulence. A split-step multi-phase screen method is employed to simulate the propagations of laser beams. Then a series of simulations with different refractive index structure parameter Cn2 and beacon wavelengths are studied. We show that under weak turbulence, the optimal wavelength of beacon is similar to the launched beam, as is widely investigated and concluded. However, beacons with longer wavelength are preferred under strong turbulence, especially with a general wavefront reconstruction algorithm without considering branch points. This research would be helpful to for designing adaptive optics systems to improve beam qualities in strong turbulence with adaptive optics systems.
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