Adaptive turbulence compensation with a hybrid input–output algorithm in orbital angular momentum-based free-space optical communication

Yin, Xiaoli; Chang, Huan; Cui, Xiaozhou; Ma, Jianxin; Wang, Yongjun; Wu, Guohua; Zhang, Lijia; Xin, Xiangjun

doi:10.1364/ao.57.007644

Cited by 53 publications

(13 citation statements)

References 27 publications

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“…All forms of structured light appear to be adversely affected by turbulence in some manner or other, and in these instances it is beneficial to compensate for the effects of atmospheric turbulence. Several mitigation techniques have been employed in the compensation of scalar modes distorted by atmospheric turbulence and these include making use of adaptive optics [165][166][167][168][169][170][171][172][173][174], iterative approaches [165], [174], [175] and most recently deep learning algorithms [172], [176]. While some comparison studies of the different techniques suggest that adaptive optics will outperform iterative approaches when compensating for distorted OAM beams [174], some studies recommend a combination of different techniques to boost the performance of free-space communication links [177], [178].…”

Section: Correction Schemesmentioning

confidence: 99%

Structured Light in Turbulence

Cox

Mphuthi

Nape

et al. 2021

IEEE J. Select. Topics Quantum Electron.

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Optical communication is an integral part of the modern economy, having all but replaced electronic communication systems. Future growth in bandwidth appears to be on the horizon using structured light, encoding information into the spatial modes of light, and transmitting them down fibre and free-space, the latter crucial for addressing last mile and digitally disconnected communities. Unfortunately, patterns of light are easily distorted, and in the case of free-space optical communication, turbulence is a significant barrier. Here we review recent progress in structured light in turbulence, first with a tutorial style summary of the core concepts, before highlighting the present state-of-the-art in the field. We support our review with new experimental studies that reveal which types of structured light are best in turbulence, the behaviour of vector versus scalar light in turbulence, the trade-off of diversity and multiplexing, and how turbulence models can be exploited for enhanced optical signal processing protocols. This comprehensive treatise will be invaluable to the large communities interested in free-space optical communication with spatial modes of light.

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Section: Correction Schemesmentioning

confidence: 99%

Structured Light in Turbulence

Cox

Mphuthi

Nape

et al. 2021

IEEE J. Select. Topics Quantum Electron.

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“…This, in turn, leads to crosstalk between neighboring OAM modes and degradation of the information capacity of the free-space optical link [12][13][14][15][16]. Adaptive optics has been used as the standard approach to compensate for distortions caused by thin turbulence [17][18][19], but it remains a challenge to compensate for beam distortions caused by strong or volumetric turbulence. * zhiminshi@usf.edu Other approaches such as image recognition based on artificial intelligence and machine learning [20][21][22][23] have also been demonstrated to resolve the information encoded in severely distorted structured beams through turbulence.…”

Section: Introductionmentioning

confidence: 99%

Compensation-free high-dimensional free-space optical communication using turbulence-resilient vector beams

et al. 2021

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Free-space optical communication is a promising means to establish versatile, secure and high-bandwidth communication between mobile nodes for many critical applications. While the spatial modes of light offer a degree of freedom to increase the information capacity of an optical link, atmospheric turbulence can introduce severe distortion to the spatial modes and lead to data degradation. Here, we demonstrate experimentally a vector-beam-based, turbulence-resilient communication protocol, namely spatial polarization differential phase shift keying (SPDPSK), that can reliably transmit high-dimensional information through a turbulent channel without the need of any adaptive optics for beam compensation. In a proof-of-principle experiment with a controllable turbulence cell, we measure a channel capacity of 4.84 bits per pulse using 34 vector modes through a turbulent channel with a scintillation index of 1.09, and 4.02 bits per pulse using 18 vector modes through even stronger turbulence corresponding to a scintillation index of 1.54.

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“…With the increasing demand for underwater resource development and utilization, the study of underwater optical communication systems with high information capacity has become a research hotspot in the field of underwater optical communication networks [1][2][3][4][5][6]. Recently, it has become one of the main targets of researchers in this field to improve the theoretical channel capacity of the optical communication system or to control the channel attenuation and channel capacity by selecting a new signal source (beam) [7][8][9][10][11][12][13][14][15][16][17], using adaptive optical systems [18] and by utilizing optimized signal coding technology [19][20][21]. It is well known that the orbital angular momentum (OAM) mode, carried by photons, provides a new dimension that can be encoded [22], and that the OAM module is related to the spatial distribution of wave function [22].…”

Section: Introductionmentioning

confidence: 99%

Received Probability of Orbital-Angular-Momentum Modes Carried by Diffraction- and Attenuation- Resistant Beams in Weak Turbulent Oceans

Yan

Yang

Qin

et al. 2020

JMSE

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High performance underwater wireless optical communication systems are the key to the construction of high quality underwater optical communication networks. However, seawater absorption and seawater turbulent diffraction should be the main factors limiting the performance of underwater optical communication systems. For this reason, we established the probability model of the orbital angular momentum (OAM) mode received by the communication system to study the influence of the absorbable turbulent seawater channel on the underwater optical communication system with an anti-diffraction and anti-attenuation random (DARR) beam as the signal carrier. In the study, the DARR beam with a large truncated Gaussian aperture was adopted as the signal carrier, seawater absorption was characterized by the complex refractive index of seawater, and seawater turbulence was described by the power spectrum of the refractive index of seawater. By analyzing the relationship between the received probability of the OAM mode of DARR beams and the dissipation rate of kinetic energy per unit of mass of fluid, the ratio of temperature and salinity, dissipation rate of the mean-squared temperature, and other parameters, we show that one can select longer wavelength, smaller OAM quantum number and smaller received diameter to increase the received probability of OAM signal modes. The disturbance of turbulent seawater to the OAM modes with different quantum numbers carried by the DARR beam is less than the corresponding OAM modes carried by the Laguerre–Gaussian beam. Our paper shows that the DARR beam can mitigate the absorption and disturbance of turbulent seawater.

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Adaptive turbulence compensation with a hybrid input–output algorithm in orbital angular momentum-based free-space optical communication

Cited by 53 publications

References 27 publications

Structured Light in Turbulence

Structured Light in Turbulence

Compensation-free high-dimensional free-space optical communication using turbulence-resilient vector beams

Received Probability of Orbital-Angular-Momentum Modes Carried by Diffraction- and Attenuation- Resistant Beams in Weak Turbulent Oceans

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