Experimentally evaluating beam scintillation and vortex structure as a function of topological charge in underwater optical turbulence

Avramov-Zamurovic, Svetlana; Nelson, Charles; Esposito, Joel M.

doi:10.1016/j.optcom.2022.128079

Cited by 8 publications

(2 citation statements)

References 28 publications

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“…The goal of this study is to explore the trade space of how the size and shape of an OAM beam influences the scintillation and speckle size as a function of vortex size in strong underwater turbulence. It has been observed in simulation and experiment that higher order modes contain different scintillation properties from Gaussian beams depending on the location within the intensity profile [15][16][17][18] . Experimental comparisons were performed on perfect vortex beams that contained the same beam size with similar scintillation properties 19 and for different beam sizes 20 .…”

Section: Introductionmentioning

confidence: 99%

Propagation of Laguerre-Gaussian beams through underwater optical turbulence

Ferlic,

Laux,

Mullen

2024

Ocean Sensing and Monitoring XVI

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In the ocean, underwater currents are driven by various natural effects attributed to heat transfer through water. The movement of heat subsequently affects light propagation due to changes in the water's refractive index leading to optical phase distortions. Applications implementing laser beams containing structured phase profiles are prone to being distorted by this underwater optical turbulence. Typical distortions of these beams can include beam wander, intensity and phase variations, and beam spreading that can limit their effectiveness for applications including free-space optical communication, imaging, or sensing. Experimental and theoretical studies have shown optical vortices, a form of structured light, propagate differently through optical turbulence compared with Gaussian beams. Changes in propagation are observed by varying the amount of orbital angular momentum (OAM) a vortex beam carries that increases the beam size as OAM increases. This experimental study intends to fairly compare Laguerre-Gaussian (LG) beams to Gaussian beams after propagation through underwater turbulence by normalizing the initial beam size using the RMS radius. The metrics chosen are the mean scintillation, on-axis intensity, and intensity correlation. Results show the scintillation and on-axis intensity, when chosen at locations along the LG beam annuli, are similar for different LG beams. When the initial beam waist is normalized, the speckle field correlation width and peak correlation energy decreases as RMS radius increases. These results show that structured light is not independent of the effects of beam size and divergence, similar to Gaussian beams, to determine propagation effectiveness or robustness.

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Section: Introductionmentioning

confidence: 99%

Propagation of Laguerre-Gaussian beams through underwater optical turbulence

Ferlic,

Laux,

Mullen

2024

Ocean Sensing and Monitoring XVI

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“…Another way is to use OAM modes for encoding, where each OAM mode corresponds to a different data symbol, and all these symbols make up an alphabet. 3 The data is encoded using different OAM modes and sent through the atmosphere, where it is received and decoded to obtain the data symbols. An overview of the use of OAM beams in optical communication is given by Willner et al 4 and Wang et al 5 Further author information: (Send correspondence to Miranda van Iersel): E-mail: mvaniersel1@udayton.edu…”

Section: Introductionmentioning

confidence: 99%

Propagation of OAM beams through atmospheric turbulence: comparison of simulation and experiment

van Iersel,

2023

Laser Communication and Propagation Through the Atmosphere and Oceans XII

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The interest of beams carrying orbital angular momentum (OAM) for free-space optical communication (FSOC) has increased over the years, due to the large number of orthogonal modes which can be used to transmit data at high data rates, and the secure transmission it offers. One of the main concerns in FSOC applications is atmospheric turbulence through which all beams propagate. The atmospheric turbulence is degrading the quality of the laser beam, due to the creation of intensity variances, beam wander, loss of spatial coherence, and OAM cross talk. A wave optics simulation framework is used to model OAM beam propagation through atmospheric turbulence. In these simulations Laguerre-Gaussian (LG) beams are used as beams carrying OAM. The atmospheric turbulence is modeled as phase screens and a split-step algorithm is used to model the beam propagation.LG beams with different mode order are propagated through atmospheric turbulence of different strengths. The results will be compared against experiments performed in the laboratory.

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