Fiber-optic Communication Lines Research Articles

METHOD OF EVALUATION THE EFFICIENCY OF FIBER-OPTIC CABLES MODELS WITH MULTI-MODULAR DESIGN BASED ON MASS AND DIMENSIONAL INDICATORS

Context. Today, the leading cable production plants in many countries of the world manufacture single- and multi-module designs of fiber-optic cables (FOC) with different protective covers and the number of fibers. This creates a wide range of possible FOC models for different consumer (buyer) requirements. However, the lack of openness of prices for FOC for the consumer, in particular for the project organization, and the desire of the manufacturer to save on production creates a need for the development and research of a method for evaluating the effectiveness of FOC of a multi-module design. In the work, it is proposed to do this by analyzing a number of optical cable models according to parameters-criteria – the compactness coefficient and the economic efficiency coefficient of the FOC by diameter. Objective. To develop a method of evaluation the efficiency of fiber-optic cables models with multi-modular design based on mass-dimensional indicators, which will allow to quickly choose an appropriate model of the FOC with the given initial data. Method. A method of evaluating the efficiency of the FOC modular design has been developed and proposed. It is based on the comparison of cable models and the selection of the most appropriate of them at given initial data. The paper proposed and introduced parameters-criteria for this – the compactness coefficient υ and the efficiency coefficient according to the diameter of the cable E0 – which show the connection of the design characteristics of the FOC to a certain parameter of its structure. At the same time, the most effective model (design) of the FOC compared to the basic models in terms of technical conditions, both from the point of view of the manufacturer and the customer, consists in lower material costs for its production while simultaneously ensuring the specified requirements for the cable (first of all, number of fibers and mechanical strength). This will allow, at the stage of cable design, to make an appropriate choice of its model with given initial parameters and to develop such a design of the FOC, which will allow to minimize the dimensions (and therefore the material capacity and cost) of the model without losing its quantitative and qualitative characteristics. Results. The paper presents the results of the development and research of the method of evaluating the efficiency of the FOC with multi-module structure based on mass and dimensional indicators. For example, using the developed method, it is shown that it is possible to choose a FOC model with a diameter smaller by 10.9% and save 15.5% of the cable cost for each kilometer of the fiber optic communication line while ensuring the initial requirements for the cable. Conclusions. The scientific novelty of the work results is that, method of evaluation the efficiency of a modular FOC design has been first developed, which allows at the cable design stage to compare the model with the cable design according to the technical conditions (TC) and the appropriate choice of this model with the given initial parameters. The practical significance lies in the possibility of using this method to make an accelerated selection of the cable model at the stage of its design, while simultaneously providing the necessary capacity of the FOC with optical fibers and minimizing the cost of its materials and dimensions.

Holographic methods of image transmission over multimode optical fiber for increased bandwidth of fiber-optic communication lines

Holographic methods of image transmission over multimode optical fiber for increased bandwidth of fiber-optic communication lines

Identification of Lightning Discharge Parameters by Its Effect on Fiber-Optic Communication Lines

Identification of Lightning Discharge Parameters by Its Effect on Fiber-Optic Communication Lines

Анализ существующих методов обеспечения защиты информации в волоконно-оптических линиях связи

The problem of protection against unauthorised access to data is considered and the results of comparing existing methods of extracting data from optical fibreare presented, the possibility to develop algorithms and identification principles that would help control information leakage channels in fibre-optic transmission systems. Developments to solve the problem of information security, in two directions are described. The classification of methods of obtaining information, the physical principles of formation of leakage channels, as well as the methodology for transmitting the proportion of optical radiation outside the propagation environment, as well as the structure, principles of operation, and trends in the development of monitoring systems are presented. Both the advantages and limitations of methods are described. Information is given about the proposed analysis system based on a neural network for more accurate detection of unauthorised connection to the network.

ТАЛШЫҚТЫ-ОПТИКАЛЫҚ БАЙЛАНЫС ЖОЛДАРЫ НЕГІЗІНДЕ ЭНЕРГИЯ ТАРАТУ ЖҮЙЕСІНІҢ ЗЕРТХАНАЛЫҚ ҮЛГІСІН ӘЗІРЛЕУ ЖӘНЕ ЗЕРТТЕУ

In this article, a laboratory sample of an energy transmission system over a fiber-optic communication line is being developed and investigated, which makes it possible to provide power to autonomous ultra-low-power electronic devices located at a considerable distance from energy sources. The system being developed will make it possible to abandon the use of copper conductors and batteries for autonomous stationary devices, which is associated with certain difficulties from the point of view of technical implementation. The result of this study is a developed laboratory sample that allows measuring the values of current and voltage in the branch of the photodetector. The method of an equivalent generator was used, as well as the well-known laws of a circuit with two dedicated nodes for an active two- pole. When analyzing the literature, scientific achievements and discoveries in the field of research, a proprietary research concept was formulated that differs from foreign analogues. During the experiment, the photodetector was in idle, short-circuit mode and was connected to a high-resistance load. Based on experimental data, volt-ampere characteristics (VAC) were constructed using a radiation source (laser) with a power of 10 and 30 MW. The technical parameters and characteristics of the radiation source and the irradiated silicon crystal are given. The output electrical power is determined using the laws of electrical engineering, including Ohm's law. To process the results obtained, quadratic interpolation of the function, the results of the root-mean-square approximation were used, and regression analysis was also performed. Absolute and relative errors were calculated. The student's coefficient was determined with a confidence interval of 0.95. According to the results of the study, the efficiency of a laboratory sample of an energy transmission system over a fiber-optic communication line was determined.

Investigations of Single-Mode Optical Fiber Microbending Properties

This research is devoted to the study of the properties of the microbending of an optical fiber. It is shown that an increase in the diameter of a microbend at a constant force in the area of its formation led to an increase in the power of optical radiation output from the fiber in the area of the microbend. It has been established that the smallest value of the optical radiation power branched in the microbending region and the smallest value of the radiation power loss at the microbending for the entire range of wavelengths under study is observed for the G657 optical fiber. The largest value of the radiation power branched off in the microbending region and the largest value of the radiation power loss at the microbending for the entire range of wavelengths under study is observed for the G655 optical fiber. The results of the article can be used in systems for protecting information transmitted over fiber-optic communication lines.

Influence of Amplitude-Modulated Channels on Amplitude Phase Channels with Coherent Detection in Distributed-Gain Fiber-Optic Communication Lines

Influence of Amplitude-Modulated Channels on Amplitude Phase Channels with Coherent Detection in Distributed-Gain Fiber-Optic Communication Lines

Greedy and branches-and-boundaries methods for the optimal choice of a subset of vertices in a large communication network

The problems of the proposed paper are generated by the actual tasks of communication networks. The development of communication resources is accompanied by an increase in the dimension of existing communication networks, for which the usual tools for solving network problems are becoming increasingly ineffective.At the same time, the spectrum of communication network problems covers both classical graph theory problems and specialized problems linking them with mathematical models of various fields of mathematics, including optimization theory, dynamic programming, probability theory and the theory of heuristic algorithms. This paper is devoted to the study of the problem of optimal allocation of a certain resource on the objects of the communication network. In this case, a complete set of specialized equipment at the nodes of the communication network is considered as a resource. It is necessary to optimize the number of pieces of equipment with the condition that all fiber-optic communication lines of the network are under the control of installed reflectometers. To solve this problem, variants of two methods were described: the greedy algorithm and the method of branches and boundaries. On the basis of the described algorithms, the computer programs were implemented and computational experiments were carried out; in the latter, the dimension of the communication network was chosen high enough to guarantee the legality of using the selected variants of algorithms for real communication networks. A representative series of experiments has shown that it is more expedient to use variants of the greedy heuristic algorithm for the group of problems under consideration, this paper contains a detailed argumentation of the result obtained. The considered problem can also be transferred to cases of optimal placement of other resources on the objects of the communication network. At the same time, if there is a specific objective function, there will be another formalization of restrictions. But the approaches to choosing the optimum may be identical, which makes the results obtained in the paper more important due to their participation in potential generalizations of the problem.

Spectral Division of the Optical Fiber Passband Using Narrowband Controllable Filter on the Base of Semiconductor Waveguide Microresonator

We analyze the new principle of multichannel spectral division of optical fiber passband using controllable narrowband integrated optical filters composed of two-coupled ring microresonators made of different semiconductor materials. It is shown that appropriate selecting the semiconductor material and optimizing the design factors of selective optical element allows creating the simple and economical integrated optical filter with bandwidth 0.1 nm, frequency separation between adjacent optical carriers 0.2 nm and signal-to-noise ratio 50 dB. Utilizing such filters in optical fiber communication lines makes it possible to increase the number of transmitted in parallel optical carrier wavelengths up to 160 and even more, i.e., to provide the traffic transmission with the speed up to 1.6 Tbit/s in one direction and in single optical fiber

Modeling and numerical simulation of the gain spectrum of Thulium-doped broadband fiber amplifiers

Nowadays, due to the complex signal medium conversion process of semiconductor laser amplifiers, the optical fiber amplifier, which is a new type of all-optical amplifier, is increasingly used in optical fiber communication lines for signal amplification because it can directly perform all-optical amplification of signals and are especially suitable for relay amplification of long-distance optical communications. Our research project is the gain spectrum of the Thulium-doped broadband fiber amplifier. The signal wavelength range is from to . The goal is to obtain the gain spectrum with fiber length variation, doping concentration, and pump power. This paper follows a logical order that presents the introduction, the formulas used in the experiment, and the result and analysis. According to the output wavelength range, energy level structure, and electronic transition process, we designed the pump wavelength and established the rate and power propagation equations. Eventually, gain spectrum with a variation of fiber length, doping concentration, and pump power is available using MATLAB for programming and calculating. With our research achievement, a more efficient optical fiber amplifier is possible to be made in the future.

Research and analysis of the efficiency fiber-optic communication lines using DWDM technologies

The performance indicators fiber-optic communication lines using spectral technology with separation communication channels are analyzed. The effectiveness of the use network resources optical telecommunication systems using spectral technologies based on the architectural concept of the next NGN (NGN, Next Generation Network) and future FN (FN, Future Network) networks has been studied. This work is devoted to the construction methods for calculating the indicators optical networks and the study methods and tools for improving the efficiency using network and channel resources fiber-optic communication lines using dense spectral multiplexing optical signals with separation communication channels. The problem ensuring effective management channel and network resources in optical communication networks are considered. As a result of the study technology spectral multiplexing, a new approach to the construction of a calculation method is proposed that describes the efficiency managing network and channel resources in fiber-optic communication lines, taking into account the numerous requirements their parameters and transfer characteristics. On the basis of the calculation method, analytical expressions are obtained that allow estimating the resources of the system, indicators informational and spectral efficiency of the functioning fiber-optic communication lines. The results of the research can be applied by cellular operators when designing an optical telecommunications network, in particular, to determine the optimal value of the capacity optical systems based on wavelength multiplexing technology and modulation spectral efficiencies.

New Optical System for Long Distance Control of Electrical Energy Flows

The problems that arise during the transmission of control commands for key elements and data on their execution via communication systems over long distances at energy facilities are considered. The necessity of a new approach to solving this problem using a fiber-optic communication line (FOCL) is substantiated. A new design of analog FOCL has been developed for transmitting control commands for key elements of substations and switching data. A new method for forming an optical signal in a laser transmitting module using direct current modulation is proposed. The advantages of using a new method for generating commands for control signals and switching data using a sequence of command codes compared with digital signals currently used in control and monitoring systems are substantiated. The main parameters of the developed analog FOCL have been calculated. An experimental prototype of an analog FOCL was assembled, and research was conducted. The results of calculations and experimental data are compared. The directions for further modernization of the developed FOCL are determined to increase the distance for transmitting an optical signal up to 600 km without the use of servers, the maintenance of which in the power transmission line system in some cases is challenging, expensive, and not always possible.

High-precision comparison of time scales over fiber optic lines using satellite modems with additional tone modulation

The use of a new type of modems with pseudonoise coding and additional tone modulation designed to compare reference time scales over telecommunication geostationary satellites is considered. Experimental studies were carried out on the possibility of comparing time scales of hydrogen keepers from the State primary standard of unit of time, frequency and national time scale using these modems via an optical link. A fiber-optical lines of various lengths were used for a two-way signal transmission. The output radio-frequency signals of the modems connected to the optical transmitters at the ends of the fiber-optical lines were transmitted towards each other on an optical carrier with a wavelength of 1.55 μm. Demodulation of optical signals into the radio frequency range was carried out using optical receivers at the ends of fiber lines. The results of experimental evaluation of type A uncertainty by comparing time scales using fiber-optical lines with 50, 100, and 200 km of length are presented. For the 200 km line, the type A measurement uncertainty does not exceed 3 ps for one day of averaging interval. For the first time, it has been experimentally shown that the implementation of the method of time scales comparison using modems with pseudo-noise coding and additional tone modulation over 200 km of fiber line is possible without the intermediate optical amplifiers. The result opens up the prospect of creating cascaded systems for comparing time scales of remote standards via fiber-optic communication lines with a smaller number of intermediate optical amplifiers.

РАСПРЕДЕЛЕННОЕ ЗОНДИРОВАНИЕ ВОЛОКОННО-ОПТИЧЕСКИХ ЛИНИЙ СВЯЗИ С ИСПОЛЬЗОВАНИЕМ РАССЕЯНИЯ БРИЛЛЮЭНА

The report discusses the main aspects of distributed sensing of fiber-optic communication lines using Brillouin scattering. The results of the study of the main functional capabilities of the method of coherent reflectometry and the method of counter propagating waves are presented. Special attention is paid to the principles of construction of reflectometric systems and the analysis of requirements for optical radiation sources. In conclusion, the main problems and prospects of practical implementation of the investigated method in the practice of monitoring fiber-optic communication lines are formulated

IMPACT OF LIGHTNING ON OPTICAL FIBERS

The study of trigger lightning is of great practical importance, since the action of protective structures and lightning rods, as well as the development of lightning discharges in high-rise buildings and in the mountains, begins as in trigger lightning with the development of a positive leader to the cloud, and flashes of γ-rays possibly occur during lightning discharges with high structures, which is confirmed by practice, since the occurrence of X-ray and γ-rays was observed inside or close to clouds and on mountain tops. If an optical cable contains metal elements in its design, then they are exposed to current, the value of which can reach several tens of kiloamperes. It is the magnitude of the current during lightning strikes and the consequences of its impact on objects that have always attracted the attention of researchers, while the other characteristics of lightning have received less attention. Meanwhile, the return stroke phase of the lightning strike process, during which a current of hundreds of kiloamperes can flow, is a relatively short-lived part of the lightning strike. Recent research into lightning has revealed surprising new phenomena that are not yet fully understood and require further study to determine the dangers they pose to fiber optic communication lines and the need for possible protective measures.

Trajectory of economic development of Bukhara region during digitalization

This research demonstrates the beginning of the trajectory of the economic development of the Bukhara region during digitalization. Such indicators as the size of resident working-age population, the number of enterprises and organizations connected to the Internet, the length of fiber-optic communication lines, which are the factors affecting the growth of the gross regional product, have been analyzed based on the multifactorial econometric models. This research, along with the relevant literature review, provides opinions, conclusions and proposals of the authors of this research.

Моделирование противодействия скрытому перехвату информационного сигнала восходящего потока данных в пассивной сети оптического доступа

The article considers the simulation of countering the covert interception of confidential information transmitted in the upstream data stream of the passive optical access network of the point-to-multipoint architecture (P2MP PON-TDM). The secrecy of the intercep tion is due to the presence of back-reflected signals in the split connections of the backbone section of the fiber-optic communication line of the passive optical access network. To counteract this method of information interception, it is proposed to transmit an interference signal in the downward direction at a wavelength of 1310 nm. Evaluation of the effectiveness of this method is carried out by modeling in OptiSystem CAD. The result of the simulation are graphs of the dependence of the Q-factor on the inverse optical losses in the split connections and on the optical power level of the interference signal. Based on the analysis of graphs, the proposed method is considered effective provided that the level of optical power of the interference and information signal reflected from the split con nection of the main fiber optic cable on the subscribers' side is equal. To counteract, it is enough to apply one source of interference, the parameters of which are similar should be similar to the parameters of the upstream signal. Recommendations are also given to counteract the covert interception of upstream data in the P2MP PON-TDM optical access network.

On the causes of electrothermal destruction of fiber-optic communication lines placed on the structures of AC overhead wires

The paper analyses the impact of the electromagnetic field of an alternating current catenary section on a fiber-optic cable suspended on the structures of the catenary system or on the overhead wires of the Centralised Traffic Control (CTC). Based on this calculation, conclusions have been made about the negative impact of alternating current electric fields with high vorticity.

Peculiarities of pulsed laser deposition of thin InGaAsN films in an active background gas atmosphere

III-V-N compounds are a promising class of solid solutions that have the prospect of being used in optoelectronic devices operating in a wide spectral range up to 3 μm, as well as for increasing the efficiency of photodetectors, lasers in fiber-optic communication lines and telecommunication systems. In this work, the features of various methods for obtaining new III-V-N semiconductor materials are investigated. Thin InGaAsN films were obtained by pulsed laser deposition on GaAs (100) and Si (100) substrates in an active background gas atmosphere. Pulsed laser deposition of thin InGaAsN films was carried out using an In0.02Ga0.98As target in an atmosphere of a highly pure argon-nitrogen mixture at a pressure of 2, 5, and 10 Pa. The source of laser radiation was an AYG:Nd3+ laser with a wavelength of 532 nm (second harmonic), laser radiation energy density of 2.3 J/cm2, pulse repetition rate of 15 Hz, and pulse duration of 10 ns. The substrate temperature was 350 °C, the deposition time was 60 minutes. It is shown that the surface of thin films is textured with microdroplets. It has been established that microdroplets on the surface of a thin film are formed by metallic indium. It has been established that the distribution of indium microdroplets over the film surface is mainly ordered in the form of lines. This phenomenon can be explained by the presence of misfit dislocations. The average size of microdroplets on the surface of the InGaAsN film on GaAs (100) was about 30 nm, and their density did not exceed 0.076 μm–2. For comparison, in films obtained on Si substrates at a pressure of 2 Pa, the highest microdroplet density was 0.26 μm–2. The lowest density of microdroplets on the surface (0.17 μm–2) was noted in samples of a thin film of InGaAsN on Si (100) obtained at a pressure of 10 Pa. It is noted that the intensity of the local phonon vibrational mode LVM InN at a frequency of 430 cm–1 increases with increasing pressure of the argon-nitrogen mixture during pulsed laser deposition in the Raman scattering spectra of InGaAsN films on Si. In the Raman spectra of InGaAsN films on Si, second-order phonon modes LVM InN and LVM GaN were detected at frequencies of 450 cm–1 about 470 cm–1, respectively. This confirms the presence of nitrogen in a thin InGaAsN film obtained by pulsed laser deposition. It is shown that an increase in the pressure of the argon-nitrogen gas mixture during pulsed laser deposition contributes to an increase in the nitrogen concentration in thin InGaAsN films on Si. It has been established that the nitrogen concentration in InGaAsN films obtained at a pressure of 10 Pa on GaAs (100) and Si (100) substrates differs insignificantly and amounts to 1.9 % and 1.8 %, respectively. The presented results will make it possible to create highly efficient photoelectric converters and photodetectors for the near and mid-infrared range up to 3 μm based on the obtained InGaAsN thin films.

ОЦЕНКА ВЛИЯНИЯ ФУНКЦИОНАЛЬНЫХ ЭЛЕМЕНТОВ НА ПАРАМЕТРЫ СИСТЕМЫ КВАНТОВОГО РАСПРЕДЕЛЕНИЯ КЛЮЧА НА ОСНОВЕ ПРОТОКОЛА B92

The influence of the parameters of functional elements on the energy, time and probabilisticcharacteristics of the quantum key distribution system (QKD) based on the B92 protocol is studied.The dependences of the probability of writing correct and erroneous bits into a raw quantumkey sequence are plotted for various lengths of a fiber-optic communication line (FOCL) and theuse of various lasers (EML-laser; DFB-laser; VCSEL-laser and FP-laser) and photodetectormodules (id201; id210; id220; id230). Thus, changes in the probability of writing a correct bit intoa raw quantum key sequence are much more significant than changes in the probability of writingan erroneous bit (50.9 times versus 3.3 times with FWHM=80 pm and a change in the length ofthe FOCL from 10 to 100 km). This is due to the fact that with an increase in the length of theFOCL, the probability of the absence of registration at the receiving station of photons or darkcurrent pulses (DCP) sharply increases. Numerical material indicates a direct proportional dependenceof the probability of writing an erroneous bit on the frequency of generation of noisepulses of single-photon avalanche photodiodes (SAPD). So, with an increase in the frequency ofoccurrence of DCP by 60 times (from 100 to 6000 Hz), the probability of recording an erroneousbit also increases by 60 times (for example, with a FOCL length of 100 km – 6.39 versus 383.3).It has been established that the root-mean-square deviation of the photon delay time is directly proportional to the length of the FOCL and the width of the laser spectrum. With a spectrum widthof FWHM=10 pm and an increase in the FOCL length from 10 to 100 km (by a factor of 10), thestandard deviation of the photon delay time also increases by a factor of 10 (from 4.16 to 41.6 ps).To achieve the best performance of the QKD system as a whole, it is advisable to use a laser witha minimum width of the radiation spectrum, for example, an EML-laser. However, EML-lasers areconsidered the most complex and expensive of all the considered types of lasers, so the use ofEML-lasers significantly increases the cost of the entire QKD system.