Atmospheric Optical Communication Research Articles

Applications of atmospheric optical communication equipment

Applications of atmospheric optical communication equipment

Prospects for the Use of Atmospheric Optical Communication at Nuclear and Fusion Facilities

An analysis of the prospects for the use of atmospheric optical communication lines at industrial nuclear energy installations, including thermonuclear (fusion) reactors and energy facilities with on-site fuel reprocessing plants, was carried out. It is shown that modern atmospheric communication terminals make it possible to implement high-speed data exchange within the perimeter of energy complexes, as well as to provide an external backup communication channel protected by use of quantum key distribution technology. The absence of the need to lay special cables through limited-access areas to organize high-speed data transmission provides a significant advantage of atmospheric communication systems over any wired communication systems. A methodology is presented for assessing the feasibility of using atmospheric optical communications at nuclear facilities, and based on long-term meteorological observations in the area where ITER (International Thermonuclear Experimental Reactor) is located, graphs of the availability of atmospheric communications are constructed. The high prospects of using atmospheric laser communication at nuclear and fusion facilities are shown.

Power amplification in the core area of radial carpet beams

We investigate the power redistribution in radial carpet beams (RCBs). We show that RCBs have increased power in the core area, which surrounds the central patternless area, as they propagate. We present both theoretical and experimental evidence that RCBs self-amplify in the core area due to their radial expansion. We examine the power carried by a main intensity spot of different RCBs produced by the diffraction of a plane wave from amplitude/phase radial gratings with sinusoidal/binary transmission profiles. We find that the core area, which has a complex intensity distribution, increases in power as the beam propagates. This feature distinguishes RCBs from other beams and makes them self-amplifying-like beams. Thus, the power amplification in RCBs is an internal effect caused by the continuous transfer of power from the patternless area to the core area. The power transfer to the core area also improves the stability of the beam in turbulent environments such as the atmosphere, making it a promising candidate for atmospheric optical communication. We discuss the practical realization of RCBs with a finite-radius beam and a radial grating. We define a “power amplification length” as the propagation distance at which the outer radius of the core area of the beam equals the beam radii at the grating. For instance, for the beam radii of 5 and 50 cm at the grating with 20 spokes, the values of these distances are 230 m and 23 km, respectively.

Regulation of atmospheric optical quantum communication links

The Russian Federation in 2023 adopted the concept of regulation of the quantum communication industry until 2030. The authors of this article took part in its development. The document substantiates the need to improve the legislation in optical communication. The study reveals that there is no global reference system for legally regulating optical communication, which will pose challenges in effectively overseeing atmospheric optical quantum communication lines. The article presents priority measures aimed at regulating atmospheric optical quantum communication lines, which will expand the commercial potential of quantum communication. The authors propose measures to protect the rights of users of quantum communication services, as well as the rights of owners of atmospheric optical quantum communication lines. In order to facilitate the operation of atmospheric optical quantum communication lines, it is essential to adopt measures beforehand, as legal uncertainties pose limitations on infrastructure project development.

Non-Line-of-Sight Atmospheric Optical Communication in the Visible Wavelength Range between UAV and the Ground Surface

An opto-electronic system for non-line-of-sight (NLOS) communication using scattered laser radiation for unmanned aerial vehicle (UAV)–ground and ground–UAV schemes at a wavelength of λ = 450 nm and a ground–UAV scheme at a wavelength of λ = 510 nm are described. The symbol error rate (SER) and its standard deviation were analyzed for different schemes of the communication channel. The transceiver system included a laser source with a power supply, a modulator, a lens refractor, a bandpass filter, a photomultiplier tube (PMT), a demodulator, and a receiving computer. The experimental data obtained at nighttime showed that the NLOS atmospheric optical communication at a wavelength of λ = 450 nm was feasible for the UAV–ground scheme at a baseline distance of up to 150 m for a UAV with a transmitter at a height of 10 m and at a baseline distance of up to 125 m for a UAV at a height of 20 m. For the ground–UAV scheme, stable communication was observed at baseline distances of up to 50 m for a UAV with a receiver at a height up to 30 m. The NLOS atmospheric optical communication at a wavelength of 510 nm was obtained for the ground–UAV scheme at baseline distances of up to 100 m for a UAV with a receiver at a height up to 45 m, as well as at baseline distances of up to 385 m for UAV flying at a height up to 20 m.

A Machine Learning Approach for Transmitted Power Estimation in Power Beaming Systems

Currently, predictive machine learning methods are used in many areas of life — from traffic predictions to medical diagnosis. Recently, these approaches also appeared in atmoposheric studies, first of all, for estimation of turbulence parameters, these tasks are necessary for a qualitative solution of atmospheric optical communication issues. The purpose of this work is to show the possibility and prospects of using machine learning algorithms for estimation transmitted power in power beaming systems in real time under changing atmospheric conditions. Experimental data were collected over several months on long atmospheric experimental setup, among gathered data there are such meteorological parameters as pressure, temperatures, wind speed, humidity, dew point, wind direction, solar flux. The data was collected for several locations. The power of the incident radiation was estimated from the voltage on the photovoltaic receiver. The nearest neighbors method, gradient boosting and neural networks were used as machine learning algorithms, the algorithms were compared with each other in terms of the average absolute error (MAPE) and the coefficient of determination (R2). The analysis of the results showed a good predictive ability of all models and potential of using even on the basis of simple meteorological measurements. The use of traditional methods requires much more complex measurements, such as scintillometry, or empirical approximations are used. Machine learning makes it possible to get results with only integral meteorological parameters and shows good accuracy for arbitrary conditions. Gradient boosting with R2 0.951 and MAPE 0.020 on all data was chosen as the best model. The results of this model was interpreted using the SHAP method, the dependence of the result on the input data is consistent with expectations.

Propagation of Gaussian Schell-Model Array Beams through a Jet Engine Exhaust

Here a Gaussian Shell Model Array (GSMA) beam is used to investigate the propagation characteristics in the jet engine exhaust region. It has great significance to improve various optical systems for wide application in trapping cold atoms, creating gratings, and atmospheric optical communication. We calculate analytical formulas for the spectral density (SD) and the propagation factors Mx2 and My2 of a GSMA beam. The influence of inner scale of turbulence in the jet engine exhaust region on its power spectrum has been also analyzed. According to these results, the influence of turbulence in a jet engine exhaust on a GSMA beam has been reduced by changing the parameters of light source and turbulence. For example, it is an excellent tool for mitigation of the jet engine exhaust-induced anisotropy of turbulence to increase the source coherence length, the root-mean-squared (rms) beam width, the wavelength or reduce the outer scale of turbulence.

Near-Infrared Optical Transmitting Module for Service Channel of Atmospheric Quantum Communication Line

This work presents an optical transmitting module operating in the near-infrared wavelength range for the organization of a wireless service channel in an atmospheric optical quantum communication channel. The main characteristics were measured to demonstrate the functionality of the module and to assess the quality of the transmitted signal, such as the values of the error vector magnitude and the eye diagram opening level. It was determined that the transmitting module can operate at symbol rates up to 5 GBaud. In addition, the optimal signal modulation parameters were found and the possible bit rate of data transmission in the atmospheric optical communication channel was estimated: a QPSK-modulated signal with a carrier frequency of 80 MHz and a symbol rate of 50 MBaud allowed to get a bit rate of 100 Mbit/s with an EVM value of 14%.

Position coding as a means of increasing the range of optical communications links

Subject of study. We present research on the range of atmospheric optical communications links as a function of atmospheric conditions, the types of laser beam modulation used, and the type of interference-resistant coding used. Aim. We develop an approach for increasing the range of free-space optical communications links by improving resistance to atmospheric turbulence. Methods. We show that the modulation technique and channel coding must be compatible if optimum results are to be achieved. Pulse position modulation and interference-resistant position coding are one example of such a compatible combination; a holographic code in which a sequence of pulses representing a 1D linear hologram of a single pulse replaces a single pulse in the desired position is one example of an interference-resistant code. In this case, position modulation is still being used, but in the form of multiple pulse position modulation. A holographic code takes advantage of the fact that holograms are divisible, and a fragment of the hologram can be used for recovery of transmitted data (as well as data hidden by noise). The recovery capacity of the holographic code depends on the hologram length—the number of slots per symbol interval. Main results. We show that holographic coding provides higher interference resistance and a lower probability of detector error and provides the same benefit as an increase in transmitter power. Practical significance. The benefit from holographic coding may be used to either increase the communications range or increase the communications channel reliability. Position coding has the advantages that the redundant information required for interference-resistant encoding is created within the symbol interval, does not affect the symbol repetition frequency, and has no effect on the data transmission rate.

Performance analysis of atmospheric optical communication systems with spatial diversity affected by correlated turbulence

This paper presents a complete analytical framework for obtaining the performance associated with a free-space optical (FSO) communication system with a spatial diversity and equal gain-combining technique. The system is affected by gamma–gamma scintillations with different realistic degrees of channel correlation depending only on the physical parameters of the link. We derive new analytical closed-form expressions for the average bit error rate (ABER) considering different scenarios to provide very realistic behavior of the system including different numbers of FSO receivers in several geometric configurations, with different receiving areas, different path lengths, and a variety of turbulence conditions. Furthermore, a very accurate approximate closed-form expression is also derived for the ABER of any generic coding scheme with either a very complex or, directly, no closed-form expression for its associated conditional BER that is first obtained in the ideal case of absence of turbulence. Numerical results via Monte Carlo simulation are provided to corroborate the validity of all the derived analytical expressions.

Possibility of creating a modular system for quantum key distribution in the atmosphere

The possibility of quantum key distribution in the atmosphere has been experimentally demonstrated by coupling commercially available quantum key distribution units designed for fiber-optic communication lines with atmospheric optical communication terminals. For distances up to 3100 m, data on losses in a quantum channel on an optical path were obtained and the influence of systems for intelligent adjustment of atmospheric communication terminals on the synchronization system of quantum communication blocks was studied. It has been established that failures of synchronization systems in the case of quantum key distribution in the atmosphere at distances greater than 10 m are due to the peculiarities of the algorithm implemented in the quantum communication unit. Keywords: quantum key distribution, atmospheric optical communication lines, FSO, decoy-state BB84 protocol, polarization coding.

Возможность построения модульной системы квантового распределения ключей в атмосфере

The possibility of quantum key distribution in the atmosphere has been experimentally demonstrated by coupling commercially available quantum key distribution units designed for fiber-optic communication lines with atmospheric optical communication terminals. For distances up to 3100m, data on losses in a quantum channel on an optical path were obtained and the influence of systems for intelligent adjustment of atmospheric communication terminals on the synchronization system of quantum communication blocks was studied. It has been established that failures of synchronization systems in the case of quantum key distribution in the atmosphere at distances greater than 10m are due to the peculiarities of the algorithm implemented in the quantum communication unit.

The Application Research of Atmospheric Optical Communication in Joint Modulation Transmission System

The Application Research of Atmospheric Optical Communication in Joint Modulation Transmission System

Research on Routing Algorithm of Smart Grid Atmospheric Optical Communication Network in Cloud Computing Environment

With regard to improving the transmission rate of the smart grid atmospheric optical communication network and reducing the output error code and reality, a calculation method of the smart grid atmospheric optical communication network routing based on the operation and calculation of hybrid particle swarm optimization is studied. The link structure model of the smart grid atmospheric optical communication network is established, and the network routing nodes are explored to achieve the dynamic neighborhood and node location of the optical communication network routing. Through practice, improving the transmission rate of the optical communication network of the smart electrical network and reducing the network output timeliness and error codes can be solved by the routing calculation method.

Self-splitting and propagation factors of a superimposed Hermite-Gaussian correlated Schell-model beam in turbulent atmosphere

A novel type of superimposed Hermite-Gaussian correlated Schell-model (SHGCSM) laser beam is first represented in terms of theory and then produced experimentally. Similar to a Hermite-Gaussian correlated Schell-model (HGCSM) beam, the SHGCSM beam demonstrates self-splitting features when it propagates in free space, over time the primary single beam spot that is initially seen gradually develops into four or two beam spots when it is in the far-field. The SHGCSM beam splits itself faster than the HGCSM beam when the other beam parameters are fixed, which has lower intensity at the center of beam at an intermediate distance. The four or two spots are more independent with each other, which can be used in attacking multiple targets. Compared with the propagation M2-factor of the HGCSM [Opt. Express 23, 10 (2015)], it has a lower propagation M2-factor in the non-Kolmogorov turbulence. The SHGCSM beam is unaltered to a lesser extent by turbulence compared with a HGCSM beam, which is beneficial for studies on atmospheric optical communications.

Minimization of the scintillation index of sinusoidal Gaussian beams in weak turbulence for aerial vehicle-satellite laser communications.

Minimization of the on-axis scintillation index of sinusoidal Gaussian beams is investigated by using the modified Rytov method in weak atmospheric turbulence for uplink/downlink of aerial vehicle-satellite laser communications. Among the focused cosh-Gaussian (cosh-G), cos-Gaussian (cos-G), annular, and Gaussian beams, a suitable displacement parameter for a cosh-G beam is determined that will minimize the scintillation index in uplink and downlink configurations. Then, for both uplink and downlink, the variations of the scintillation index against the propagation distance, source size, and zenith angle are examined and compared among themselves to show the optimum beam that possesses the minimum scintillation index. Sinusoidal Gaussian beams that are focused at the receiver and obtained by employing the appropriate displacement parameter, which we name the optimum beams, are recommended to obtain smaller intensity fluctuations in atmospheric wireless optical communication systems operating in vertical links in weak turbulence.

Feature issue introduction: applications of adaptive optics.

This feature issue of Optics Express follows the 2020 Imaging and Applied Optics Congress and comprises of articles on the development and use of adaptive optics across the broad range of domains in which the technique has been applied - including atmospheric correction, ophthalmology, vision science, microscopy, optical communications and beam control. This review provides a basic introduction to adaptive optics and a summary of the multidisciplinary articles included in this issue.

Research results on the influence of radiation on constructive elements of atmospheric-­optical communication lines

The research results on the radiation resistance of the element base of atmospheric-optical communication lines are produced. The technical condition of the receiver under the influence of gamma radiation will determine the operability of atmospheric optical communication lines. The influence of gamma radiation as a consequence of a man-made disaster can affect the receiver of atmospheric-optical communication lines by the formation of reversible and irreversible radiation effects. This will cause a reduction of the detection ability of the receiver of atmospheric optical communication lines. The types of radiation defects and the degree of their influence on the detection ability depend on the energy of gamma quanta, as well as on the amount of the absorbed dose of gamma radiation and its power. Analysis of methods for estimating the functioning of atmospheric optical communication lines in a man-made disaster has shown that there is a need to develop recommendations for maintaining the detection ability of receivers of atmospheric optical communication lines under the influence of gamma radiation. Further research should be conducted to develop methods that take into consideration: the peculiarities of the man-made disaster; features of formation of radiation effects in the receiver of atmospheric-optical communication lines under the influence of gamma radiation; energy, activity and physicochemical characteristics of the mixture of radioactive radiation.

Quantum-Cascade Lasers in Atmospheric Optical Communication Lines: Challenges and Prospects (Review)

The parameters of prospective samples of atmospheric optical communication lines (AOCL) or free-space optics (FSO) based on quantum-cascade lasers (QCL) as compared to those of existing commercial systems are analyzed. The results indicate that the use of QCL in FSO has significant advantages over existing systems, due largely to longwave radiation and the QCL modulation dynamics, which are limited by the picosecond lifetime of current carriers that provides the fundamental possibility of obtaining an inherent bandwidth of ≥100 GHz. Possible applications of FSO based on IR QCL and THz QCL are discussed taking into account the experimental data and unique properties of QCL radiation. Also, the use of non-traditional methods to eliminate the influence of turbulence and increase the capacity of the information transmission channel is discussed.

High-speed format 1000BASE-SX / LX transmission through the atmosphere by vortex beams near IR range with help modified SFP-transmers DEM-310GT

The possibility of constructing a near-infrared atmospheric optical communication system based on a pair of media converters of a signal format 100Base-TX / 1000BASE-T to format 1000BASE-SX / LX with SFP transceivers DEM-310GT was experimentally investigated. The FAN-OUT TUBING FTB900 SN-Y4 fiber cable connector, coming from the receiving radiation collimator for matching with the DEM-310GT transceiver, was modified. The transmitting radiation collimator is supplemented by a spiral phase plate to form a vortex beam. The influence of atmospheric influence on the data rate is analyzed.