The scintillations for weak atmospheric turbulence using a partially coherent source

Baykal, Yahya; Plonus, M. A.; Wang, S. J.

doi:10.1029/rs018i004p00551

Cited by 54 publications

(13 citation statements)

References 16 publications

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“…Comprehensive presentations of scintillation results can be found in [21][22][23]. Scintillation index is also studied for partially coherent [24][25][26][27] and incoherent [28,29] beams in weak turbulence. Complex displacement parameters incorporated in the off-axis Gaussian beams introduce transverse source coordinate dependent attenuation and phase shifts that cause the off-axis beams to form the basis for sinusoidal and hyperbolic Gaussian beams [30].…”

Section: Introductionmentioning

confidence: 99%

Partially coherent off-axis Gaussian beam scintillations

Baykal

Eyyuboğlu

Cai

2010

Journal of Modern Optics

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The scintillation index at the receiver origin is formulated for a partially coherent off-axis Gaussian beam in atmospheric turbulence by employing the extended Huygens-Fresnel principle. Our formula correctly reduces to the existing coherent and partially coherent Gaussian beam scintillation indices in the limiting cases. For off-axis Gaussian beams with imaginary, real and complex displacement parameters, the scintillation index reduces when the incidence becomes more incoherent. When the source size of the off-axis Gaussian beam increases, the scintillations increase for partially coherent sources and decrease for incoherent sources, the tendency being observed for imaginary, real and complex displacement parameters. For the fully coherent off-axis Gaussian beams, increase in the source size first causes an increase in the scintillations, eventually reaching saturation at large source sizes, the increase is not monotonic and may exhibit a peak around the Fresnel zone sized off-axis Gaussian sources. For all degrees of partial coherence, off-axis beams possessing imaginary displacement parameters exhibit larger scintillations when the displacement parameter increases for large sized incidences, however, for small sized incidences, scintillations stay at the same level when the imaginary displacement parameter increases, the fixed scintillation value being lower for more incoherent sources. For off-axis Gaussian sources possessing real displacement parameters, this behavior is reciprocal with respect to the source size, i.e. for all degrees of partial coherence, off-axis beams possessing real displacement parameters exhibit larger scintillations when the displacement parameter increases for small sized incidences, and for large sized incidences, scintillations stay at the same level when the real displacement parameter increases, the fixed scintillation value again being lower for more incoherent sources. For all degrees of partial coherence, off-axis Gaussian beams possessing imaginary displacement parameters exhibit larger scintillations than the off-axis Gaussian beams possessing real displacement parameters when the absolute value of displacement parameter increases for large sized incidences.

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Section: Introductionmentioning

confidence: 99%

Partially coherent off-axis Gaussian beam scintillations

Baykal

Eyyuboğlu

Cai

2010

Journal of Modern Optics

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“…(16) The stochastic variables F and φ k (q), which are of different nature, are separated in Eq. (16). Averaging of each factor in the sum can be performed independently because of the absence of correlations between the source fluctuations and the refractive index fluctuations.…”

Section: Beam Spread and Intensity Fluctuationsmentioning

confidence: 99%

Photon distribution function for long-distance propagation of partially coherent beams through the turbulent atmosphere

Berman

Chumak

2006

Phys. Rev. A

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The photon density operator function is used to calculate light beam propagation through turbulent atmosphere. A kinetic equation for the photon distribution function is derived and solved using the method of characteristics. Optical wave correlations are described in terms of photon trajectories that depend on fluctuations of the refractive index. It is shown that both linear and quadratic disturbances produce sizable effects for long-distance propagation. The quadratic terms are shown to suppress the correlation of waves with different wave vectors. * Corresponding author: gpb@lanl.gov 1We examine the intensity fluctuations of partially coherent beams (beams whose initial spatial coherence is partially destroyed). Our calculations show that it is possible to significantly reduce the intensity fluctuations by using a partially coherent beam. The physical mechanism responsible for this pronounced reduction is similar to that of the Hanbury-Braun, Twiss effect.

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“…Considering a single infinite plane wave this author obtained approximate analytic expressions for the scintillation index of the planar wave in the weak [23] and strong [24] turbulence regimes. Later studies extended these results to the cases of a spatially incoherent source [25] and a source that is partially coherent in both space and time [26]. More recently, Kiasaleh studied the scintillation index for a multiwavelength infinite plane wave in weak atmospheric turbulence [27,28].…”

Section: Introductionmentioning

confidence: 97%

Scintillation index for two Gaussian laser beams with different wavelengths in weak atmospheric turbulence

Peleg

Moloney

2006

J. Opt. Soc. Am. A

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We study propagation of two lowest order Gaussian laser beams with different wavelengths in weak atmospheric turbulence. Using the Rytov approximation and assuming a slow detector we calculate the longitudinal and radial components of the scintillation index for a typical free space laser communication setup. We find the optimal configuration of the two laser beams with respect to the longitudinal scintillation index. We show that the value of the longitudinal scintillation for the optimal two-beam configuration is smaller by more than 50% compared with the value for a single lowest order Gaussian beam with the same total power. Furthermore, the radial scintillation for the optimal two-beam system is smaller by 35%-40% compared with the radial scintillation in the single beam case. Further insight into the reduction of intensity fluctuations is gained by analyzing the self-and cross-intensity contributions to the scintillation index.

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The scintillations for weak atmospheric turbulence using a partially coherent source

Cited by 54 publications

References 16 publications

Partially coherent off-axis Gaussian beam scintillations

Partially coherent off-axis Gaussian beam scintillations

Photon distribution function for long-distance propagation of partially coherent beams through the turbulent atmosphere

Scintillation index for two Gaussian laser beams with different wavelengths in weak atmospheric turbulence

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