Laser beam propagation through strong turbulence

Barrett, J. L.; Budni, P. A.

doi:10.1063/1.351276

Cited by 17 publications

(7 citation statements)

References 6 publications

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“…These expressions are difficult to manipulate due to their parametric nature. In the limit of strong turbulence, a negative exponential distribution for the irradiance holds (both theoretically and experimentally, [22], [24]), which reduces to Rayleigh statistics of the optical field amplitude. In our analysis, we have considered the two extremes, the log-normal and the Rayleigh, with the expectation that the two models bound the range of performances observed in application.…”

Section: B Channel Modelingmentioning

confidence: 99%

Optical repetition MIMO transmission with multipulse PPM

Wilson

Brandt-Pearce

Cao

et al. 2005

IEEE J. Select. Areas Commun.

208

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Abstract-We study the use of multiple laser transmitters combined with multiple photodetectors for atmospheric, line-of-sight optical communication, and focus upon the use of multiple-pulseposition-modulation as a power-efficient transmission format, with signal repetition across the laser array. Ideal (photon counting) photodetectors are assumed, with and without background radiation. The resulting multiple-input/multiple-output channel has the potential for combating fading effects on turbulent optical channels, for which both log-normal and Rayleigh-fading models are treated. Our focus is upon symbol error probability for uncoded transmission, and on capacity for coded transmission. Full spatial diversity is obtained naturally in this application.Index Terms-Multiple-input/multiple-output (MIMO) systems, optical communications, pulse-position-modulation (PPM).

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Section: B Channel Modelingmentioning

confidence: 99%

Optical repetition MIMO transmission with multipulse PPM

Wilson

Brandt-Pearce

Cao

et al. 2005

IEEE J. Select. Areas Commun.

208

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“…the same order in magnitude as expected within or close to a jet engine plume, are observed [5,6]. Beam wander and broadening effects due to propagation through turbulent plumes have been studied at several wavelengths [7,8].…”

Section: Introductionmentioning

confidence: 94%

“…where a denotes a constant [5]. The transversal variation of the structure parameter is influenced by flow properties such as temperature differences, alterations in the refractive index caused by pressure and temperature variations and the scale length.…”

Section: 1mentioning

confidence: 99%

Laser beam propagation in close vicinity to a down-scaled jet engine exhaust

2004

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Laser beam propagation in severe environment such as a jet engine exhaust may influence performance of e.g. laser countermeasure and active imaging systems located on airborne platforms. Beam propagation in close vicinity to the engine plume causes performance degradation due to beam wander and beam broadening effects. In this study beam propagation effects were studied experimentally using a downscaled jet engine. Beam wander and broadening effects were studied directing a 1.55 µm laser beam parallel to the jet exhaust. The beam centroid motion increased significantly during onset of the engine. Perturbation effects were registered imaging a blackbody source using a fast infrared camera. The geometrical set-up and thrusts were altered during the experimental registrations to examine various flow conditions. A comparison of experimental results with simplified theoretical models describing propagation close to jet engine plumes will be presented. Limitations in existing models will be discussed and methods for refinements proposed.

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“…[2] In recent years, with the increasing demanding in mounting laser systems on aircraft for applications in optical communications, active imaging and countermeasure systems (DIRCM), many studies on laser beam propagating through jet engine turbulence DOI: 10.1002/andp.202100537 have been reported. [1][2][3][4][5][6][7] It is demonstrated that the beam shape gradually transfers to an elliptical in jet engine turbulence as the propagation distance increases. [4,6] On the other hand, the laser beams will also suffer from the atmospheric turbulence over long distances.…”

Section: Introductionmentioning

confidence: 99%

The Combined Effect of Jet and Atmospheric Turbulence on the Propagation of Airborne Partially Coherent Array Beams

et al. 2022

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The exhaust from engines close to the fuselage can cause extreme turbulence and have a significant impact on the performance of airborne laser systems. In this paper, the combined effect of the jet engine and atmospheric turbulence on propagation of a Gaussian Schell-model (GSM) array beam over long distances is studied in detail. Based on the two-step propagation method, the analytical expressions of the cross-spectral density (CSD) function, mean-squared beam width and spectral degree of spatial coherence (DOC) of GSM array beams are derived. It is shown that the jet engine turbulence has a significant effect on the beam broadening even at a very short distance. As the propagation distance in the jet engine turbulence increases, the beam width is less effected by the spatial coherence. Meanwhile, the resistance of lower spatially coherent beam to the turbulence increases as the distance of the jet engine turbulence or the strength of the atmospheric turbulence increases. It is demonstrated that the effect of jet engine turbulence on the beam spreading can be equivalent to moderate or even severe atmospheric turbulence. Moreover, the DOC is a function with oscillatory phenomenon when the propagation distance is short or the strength of turbulence is low.

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Laser beam propagation through strong turbulence

Abstract: The effects of strong turbulence (C2n up to 3×10−9 m−2/3) on laser beam propagation were measured. Beam broadening of a factor of 2, and wander over several hundred microradians were observed. Long-term beam broadening agrees with values calculated from simplified analytic models.

Cited by 17 publications

References 6 publications

Optical repetition MIMO transmission with multipulse PPM

Optical repetition MIMO transmission with multipulse PPM

Laser beam propagation in close vicinity to a down-scaled jet engine exhaust

The Combined Effect of Jet and Atmospheric Turbulence on the Propagation of Airborne Partially Coherent Array Beams

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