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Proceedings Paper

A geometrical optics approach for modeling aperture averaging in free space optical communication applications
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Paper Abstract

Intensity fluctuations at the receiver in free space optical (FSO) communication links lead to a received power variance that depends on the size of the receiver aperture. Increasing the size of the receiver aperture reduces the power variance. This effect of the receiver size on power variance is called aperture averaging. If there were no aperture size limitation at the receiver, then there would be no turbulence-induced scintillation. In practice, there is always a tradeoff between aperture size, transceiver weight, and potential transceiver agility for pointing, acquisition and tracking (PAT) of FSO communication links. We have developed a geometrical simulation model to predict the aperture averaging factor. This model is used to simulate the aperture averaging effect at given range by using a large number of rays, Gaussian as well as uniformly distributed, propagating through simulated turbulence into a circular receiver of varying aperture size. Turbulence is simulated by filling the propagation path with spherical bubbles of varying sizes and refractive index discontinuities statistically distributed according to various models. For each statistical representation of the atmosphere, the three-dimensional trajectory of each ray is analyzed using geometrical optics. These Monte Carlo techniques have proved capable of assessing the aperture averaging effect, in particular, the quantitative expected reduction in intensity fluctuations with increasing aperture diameter. In addition, beam wander results have demonstrated the range-cubed dependence of mean-squared beam wander. An effective turbulence parameter can also be determined by correlating beam wander behavior with the path length.

Paper Details

Date Published: 1 September 2006
PDF: 12 pages
Proc. SPIE 6303, Atmospheric Optical Modeling, Measurement, and Simulation II, 630302 (1 September 2006); doi: 10.1117/12.679572
Show Author Affiliations
Heba Yuksel, Bogazici Univ. (Turkey)
Christopher C. Davis, Univ. of Maryland, College Park (United States)

Published in SPIE Proceedings Vol. 6303:
Atmospheric Optical Modeling, Measurement, and Simulation II
Stephen M. Hammel; Anton Kohnle, Editor(s)

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