25 May 2005 Numerical experiments in atmospheric scintillation correlation for applications in dual channel optical communications
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A method for reducing noise in near-IR laser communications has been proposed that relies upon the dual wavelength output of the He-Xe laser having a high level of noise coherence. However, in transmissions through the atmospheric boundary layer, an additional and significant noise component is added by atmospheric scintillation. These scintillations are mainly limited to frequencies of less than 1 kHz and are correlated in the two laser channels to a degree determined by the channel wavelength separation, the transmission range and the severity of the turbulence regime. To analyze the propagation of waves in random media one normally considers the statistics of the field. In the case of small angle forward scattering, which is the case of interest in laser propagation, field moments higher than the fourth are so difficult to solve that no solutions are known outside of the asymptotic weak and strong approximations. An alternative approach is to conduct numerical experiments in which one generates a realization of the random medium (with the desired statistics) and then calculates the wave field. We have numerically modeled the spatial irradiance intensity as a function of range from a point source under turbulence regimes typical of daytime conditions near the Earth’s surface. Simulations were performed for two closely separated channels in the near-IR (1556.5 and 1558.1 nm). We present the results of these simulations together with the implications for the mitigation of atmospheric scintillation noise by common mode rejection.
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James E. Davies, James E. Davies, Brett D. Nener, Brett D. Nener, Kenneth J. Grant, Kenneth J. Grant, Kerry Corbett, Kerry Corbett, Bradley Clare, Bradley Clare, "Numerical experiments in atmospheric scintillation correlation for applications in dual channel optical communications", Proc. SPIE 5793, Atmospheric Propagation II, (25 May 2005); doi: 10.1117/12.604750; https://doi.org/10.1117/12.604750

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