Optimal control of laser beams for propagation through a turbulent medium

Barchers, Jeffrey D.; Fried, David L.

doi:10.1364/josaa.19.001779

Cited by 36 publications

(31 citation statements)

References 16 publications

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“…In the fields of defense industry and free space communications, the beam propagation through the atmosphere leads to strong amplitude distortions degrading the system performance. During the last two decades, a significant amount of research was generated for these applications to develop adaptive optics systems correcting for both amplitude and phase distortions of a beam [20][21][22][23][24] .…”

Section: -Dm Concept For Laser Beam Shapingmentioning

confidence: 99%

“…The second DM, DM2, is optically conjugated to the pupil plane of the beam projecting aperture, so it only modifies the phase distribution of the output beam. A novel modification of the latter approach to near-field correction has been proposed by Barchers et al [21,[27][28][29] showing the potential interest of conjugating the first DM to a finite range where a turbulent layer could be present, instead of using a Fourier transforming mirror. This kind of dual-DM systems to precompensate atmospheric turbulence effects on beacon has been used during the last two decades in the military and free-space communication fields.…”

Section: -Dm Concept For Laser Beam Shapingmentioning

confidence: 99%

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Beam shaping for laser-based adaptive optics in astronomy

Béchet¹,

Guesalaga²,

Neichel³

et al. 2014

Opt. Express

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Abstract:The availability and performance of laser-based adaptive optics (AO) systems are strongly dependent on the power and quality of the laser beam before being projected to the sky. Frequent and time-consuming alignment procedures are usually required in the laser systems with free-space optics to optimize the beam. Despite these procedures, significant distortions of the laser beam have been observed during the first two years of operation of the Gemini South multi-conjugate adaptive optics system (GeMS). A beam shaping concept with two deformable mirrors is investigated in order to provide automated optimization of the laser quality for astronomical AO. This study aims at demonstrating the correction of quasi-static aberrations of the laser, in both amplitude and phase, testing a prototype of this two-deformable mirror concept on GeMS. The paper presents the results of the preparatory study before the experimental phase. An algorithm to control amplitude and phase correction, based on phase retrieval techniques, is presented with a novel unwrapping method. Its performance is assessed via numerical simulations, using aberrations measured at GeMS as reference. The results predict effective amplitude and phase correction of the laser distortions with about 120 actuators per mirror and a separation of 1.4 m between the mirrors. The spot size is estimated to be reduced by up to 15% thanks to the correction. In terms of AO noise level, this has the same benefit as increasing the photon flux by 40%.

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Section: -Dm Concept For Laser Beam Shapingmentioning

confidence: 99%

Section: -Dm Concept For Laser Beam Shapingmentioning

confidence: 99%

Beam shaping for laser-based adaptive optics in astronomy

Béchet¹,

Guesalaga²,

Neichel³

et al. 2014

Opt. Express

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“…Although AO has had considerable success in optical astronomy, its complexity, cost, and inability to correct for long range effects makes its widespread adoption for OW problematic. A full discussion of AO is beyond the scope of this article, but the study of Fried and co-workers [182][183][184][185][186][187] is particularly important in this context.…”

Section: Fade Mitigation Techniquesmentioning

confidence: 99%

A review of communication-oriented optical wireless systems

Borah

Boucouvalas

Davis

et al. 2012

J Wireless Com Network

185

104

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This article presents an overview of optical wireless (OW) communication systems that operate both in the short-(personal and indoor systems) and the long-range (outdoor and hybrid) regimes. Each of these areas is discussed in terms of (a) key requirements, (b) their application framework, (c) major impairments and applicable mitigation techniques, and (d) current and/or future trends. Personal communication systems are discussed within the context of point-to-point ultra-high speed data transfer. The most relevant application framework and related standards are presented, including the next generation Giga-IR standard that extends personal communication speeds to over 1 Gb/s. As far as indoor systems are concerned, emphasis is given on modeling the dispersive nature of indoor OW channels, on the limitations that dispersion imposes on user mobility and dispersion mitigation techniques. Visible light communication systems, which provide both illumination and communication over visible or hybrid visible/ infrared LEDs, are presented as the most important representative of future indoor OW systems. The discussion on outdoor systems focuses on the impact of atmospheric effects on the optical channel and associated mitigation techniques that extend the realizable link lengths and transfer rates. Currently, outdoor OW is commercially available at 10 Gb/s Ethernet speeds for Metro networks and Local-Area-Network interconnections and speeds are expected to increase as faster and more reliable optical components become available. This article concludes with hybrid optical wireless/radio-frequency (OW/RF) systems that employ an additional RF link to improve the overall system reliability. Emphasis is given on cooperation techniques between the reliable RF subsystem and the broadband OW system.

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“…For relay propagation, one advantage is that the received beam can be cleaned up in a relay system [24][25][26], which means the increase of the spatial correction length. To see the effects of the correction performance of the relay system in non-Kolmogorov turbulence, the dependence of PIB on α with different σ (which is defined as in Equation (10g)) is plotted in Fig.…”

Section: The Properties Of Partially Coherent Cosh-gaussian Beam To Tmentioning

confidence: 99%

“…Many factors limit the propagation of laser beams, such as turbulent atmosphere and transmission. Relay propagation at high elevation angles has been proposed to overcome this problem, which has been proved to be a valid method [25][26][27][28][29][30]. Relay propagation will be affected not only by its travel path but also by the relay system, such as the size of the receiver of relay system and the correction, which is different from the direct propagation.…”

Section: Introductionmentioning

confidence: 99%

Relay Propagation of Partially Coherent Cosh-Gaussian Beams in Non-Kolmogorov Turbulence

Tao¹,

Liu²,

Ma³

et al. 2012

PIER

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Abstract-The analytical formulas for the average intensity and power in the bucket of the relay propagation of partially coherent cosh-Gaussian (ChG) beams in non-Kolmogorov turbulence have been derived based on the extended Huygens-Fresnel principle. The influences of the beam parameters, relay system parameters and the non-Kolmogorov turbulence parameters on relay propagation are investigated by numerical examples. Numerical results reveal that the relay propagation of the beam is different from that in the case of Kolmogorov turbulence. It is shown that the relay propagation has advantages over direct propagation, and the relay propagation of partially coherent ChG beams depends greatly on the beam parameters, relay system and the generalized exponent α. The focusability of the beam at the target in non-Kolmogorov turbulence increases with larger inner scale, larger relay system radius, smaller outer scale, and smaller generalized structure constant. The results are useful for the practical applications of relay propagation, i.e., freespace communication.

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Optimal control of laser beams for propagation through a turbulent medium

Cited by 36 publications

References 16 publications

Beam shaping for laser-based adaptive optics in astronomy

Beam shaping for laser-based adaptive optics in astronomy

A review of communication-oriented optical wireless systems

Relay Propagation of Partially Coherent Cosh-Gaussian Beams in Non-Kolmogorov Turbulence

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