Theory of optical scintillation

Terrestrial Coherent Free-Space Optical Communication Systems

“…Then Phillips and Andrews proved the validity of this K distribution by experiments in the strong turbulence regime [24], [25]. The K-distribution is an accurate model of turbulence if moderate propagation distances are encountered (about 1km) or the scintillation index [11] is confined to the range (2, 3) [45].…”

“…When the optical turbulence strength extends to moderate-to-strong irradiance fluctuation regimes (when the scintillation index is greater than unity) by increasing C 2 n and/or path length L t , the scintillation index for a plane wave and that for a spherical wave are, respectively, related to the Rytov variance by [11] (σ (1 + 0.167σ 12 5 R )…”

“…It was shown in [23]- [26] that the K-distributed turbulence model provides good agreement with experimental data in a variety of FSO experiments involving radiation scattered by strong turbulence. In a recent series of papers on scintillation theory [11], [27], Andrews et al introduced the modified Rytov theory and the Gamma-Gamma PDF was proposed as a tractable mathematical model for a wide range of atmospheric turbulence levels. Other statistical models in the FSO literature to describe atmospheric turbulence are the log-normal Rician, Rayleigh and I − K models [28], [29], [44].…”

“…In (11), φ m denotes the encoded phase information. In practice, an FSO system can be employed with P LO ≫P in (t), and the DC term in (10) can be approximated by the dominant term RP LO .…”

Massive individual orbital angular momentum channels for multiplexing enabled by Dammann gratings

“…To estimate the performance of OAM-based MUX/DEMUX technology for long-distance FSO, we model the OAM beams' propagation in an atmosphere based on the Kolmogorov turbulence theory. [29][30][31][32][33] We take the random intensity and phase perturbation of OAM beams into account and calculate the crosstalk among the OAM states. We define S mn as the percentage of beam energy transferred from the OAM state m to n. While m5n, S mn is the power remaining in the original OAM state m; while m?n, S mn is the crosstalk between OAM states m and n. We define C 2 n as the refractive-index structure parameter with a unit of m 22/3 , which is related to the strength of turbulence in the atmosphere.…”