Fiber-optic Lines Research Articles

A Micro‐3‐Degree‐of‐Freedom Force Sensor for Intraocular Dexterous Surgical Robots

The continuum manipulator improves the intraocular robot flexibility during retinal surgery. Herein, a micro‐3‐degree of freedom (DOF) force sensor with a length of only 3.8 mm that can adjust the puncture angle during retinal vein cannulation (RVC) is proposed. Taking advantage of 3D printing technology, the optical fiber and injection line are embedded in the nitinol tube with flexible hinges to achieve integration of the force sensing and injection functions. A new fiber Bragg grating (FBG) configuration method and linear decoupling algorithm are also proposed herein. Static calibration experiments demonstrate excellent resolution of the force sensor, of less than 0.072 mN for transverse force and 0.738 mN for the axial force in the range from −20 to 20 mN. The proposed sensor is installed on a newly developed actuator, and an ex vivo experiment is performed on pig cadaver eyes. The interaction forces at each stage of the RVC are recorded in detail for the first time, further confirming the feasibility and effectiveness of the developed sensor for monitoring the RVC interaction forces.

Customized Optical Fiber Birefringent Sensors to Multipoint and Simultaneous Temperature and Radial Strain Tracking of Lithium‐Ion Batteries

AbstractBatteries are seen as a vital piece for actual carbon‐neutral world needs. However, as they basically operate through extremely exothermic electrochemical events, special attention must be paid to their thermal and volumetric constraints, where continuous and accurate monitoring is of great importance. Considering it, customized optical sensors, based on fiber Bragg gratings recorded in birefringent PANDA fibers (FBG‐PANDA), are developed and instrumented in a coiled configuration into a cylindrical Li‐ion battery (LiB) to simultaneously track temperature and radial strain during galvanostatic cycles, in three different battery locations, for the first time. The maximum temperature and radial strain variations are achieved in the middle and at the end of the discharge steps. This thermal behavior is correlated with the internal heat generation and transfer of thermal energy processes, with a tendency to accumulate in the LiB central zone.Good feasibility and reproducibility are observed in the optical sensor's performance and demonstrated that by operating as a multiparameter decouple system, they can decrease the complexity and intrusiveness in batteries, by using only one optical fiber line. The reported results are in accordance with the literature, indicating that such sensors could be consistently used for future applications regarding battery safety parameters sensing.

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.

CHANCES OF WRONG INFORMATION RECEPTION DURING ELECTROMAGNETIC INFLUENCE UPON OPTICAL CABLE

Long-distance communication lines are optical fiber lines in most cases now. This moment PM QPSK system (polarization-division multiplex with quadrature phase shift keying) appear. Polarization-division multiplex uses a fact that the optical signal can propagate as two orthogonal polarized modes that allows to use the modes independently and makes it possible to double carrier capacity (together with already other used multiplex system). Two orthogonal waves using in the same fiber can cause problems during lightning discharges close by cable line. Under influence of external cross electrical field (or longitudinal magnetic) the polarizations plane of lights wave can turns on angle, which depends on field value, light path length upon field action and fiber sensitivity. During the influence of external electromagnetic field issue a part of one polarization signal can pass to other orthogonal plane and it will perceive wrongly. The Wavelength Division Multiplexing (WDM) systems development with increasing number of carriers brought to transmission in the same transparency window some tens or hundreds waves. They are shifted relative to each other for some parts of nanometers during the lightning stroke. Therefore the polarization plane rotation will be different for each wave (other conditions being equal): the short waves rotated greater than the long waves. On input of optical amplifier there will be packet of waves with different polarizations, and it can produce problems to filters, optical insulators and amplifiers, to Raman amplifiers specially, which are sensitive to polarization. It is known that short and long waves are moving with different velocity as refraction index depends upon wave length. Usually the rotation angle quantity is small if resistivity of earth near cable is not heavy and if equipment does not contain sensitive to PMD (Polarization Modes Dispersion). This phenomenon passes usually unnoticed. But sometimes with strong thunderstorm and lightning stroke at a short distance the polarization plane rotation can exceed 45º or even 90º. Hereby, it is possible the complex electrical and magnetic fields influence during thunderstorm on orthogonal polarization using, that can lead to additional component appearance in orthogonal axes and to signal reception error. Error level for year is estimated.

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.

Topologi Redundansi Link Untuk Keamanan Serta Mitigasi Ketersediaan Jaringan Komputer Menggunakan Rapid Spanning Tree Protocol

The frequent occurrence of natural disasters requires telecommunications companies to require a backup internet backbone line if the telecommunications infrastructure is damaged/disconnected due to natural disasters. Reporting from inet.detik.com APJII revealed that the Jakarta-Singapore fiber optic network had broken, which had an impact on internet services in Indonesia. Fiber optic repair can take up to 2-3 weeks requiring network backup, the main solution for network backup with satellite, but problems will arise when configuration for satellite lines takes 1-2 days. Problems arise again when combined between fiber optic internet lines and satellite internet lines which cause the looping network to create network disturbances, to maintain interference, a spanning tree protocol method is needed to backup lines automatically and create link redundancy if one of the lines is problematic or disconnected. The purpose of this study is to design a link redundancy topology for security and mitigation of network availability using the rapid spanning tree protocol (RSTP) with router rb750gr3, switch rb260gs and switch dgs-108. In the RSTP network topology, it is designed with 3 redundant lines connected between the rb260gs switch and the dgs-108 switch, with an on-stick router rb750gr3 and is designed with 6 access mode vlan lines. In testing the inter-vlan network, RSTP terminates the redundancy link and then uses the ping command at the command prompt to determine how many minutes to backup the link. The NDLC method is used in determining how many seconds to backup this redundancy link using. The results of testing the link termination ether2-switch-mikrotik and ether1-switch-dlink using the "ping" command for 20 seconds in determining how many seconds to backup the link get the result that Request Time Out does not occur and the average time for each pc in determining the backup path for the pc-vlan20 22.9ms, pc-vlan30 35ms, pc-vlan70 23.5ms. The results of link termination testing ether3-switch-mikrotik and ether2-switch-dlink using the "ping" command for 20 seconds in determining how many seconds to backup the link get the result that there is no Request Time Out and the average time for each pc in determining the backup path for the pc-vlan20 23ms, pc-vlan30 24ms, pc-vlan70 43.7ms.

Using a training stand to gain skills in measuring FOCL parameters

This article is devoted to the problems of engineering education in a technical higher educational institution. In particular, obtaining an insufficient amount of practical skills and abilities in the field of systems, networks and telecommunications. This article discusses the acquisition of practical experience in the measurement of various parameters of fiber optic communication cables using measuring instruments to control the fiber optic line. For a visual demonstration of the possibility of carrying out laboratory work on this stand, the identification of the influence of connectors at the ends of fiber-optic patch cords on the operation of the line is considered. All this became possible thanks to the creation of a training stand, which is designed to train students in the specialty “Infocommunication Technologies and Communication Systems”, and the like.

Efficiency analysis of routing protocols in wireless mesh networks

An important direction in the administration of the state is the creation of a single information environment that will provide reliable feedback, timely planning and coordination of the actions of various units and structures of the state for the effective performance of assigned tasks. These issues are very relevant for the armed forces and other power structures of the state. JADC2 (Joint All-Domain Command and Control) technology was adopted in 2022 as an important strategy in the US armed forces and the armies of NATO countries. It is envisaged that JADC2 will cover all branches of the armed forces in order to combine the communications of various devices in the overall structure of command and control. To achieve success, a constant connection between a large number of domains, including sensors and control objects – Internet of Things in the military sector with the use of artificial intelligence AI/ML (Artificial Intelligence/Machine learning) must be maintained. The communication between the elements of the JADC2 architecture at the respective levels should be provided by different telecommunication networks using different physical channels, such as KH and VHF radio links, satellite communication, fixed fiber optic lines, etc. At the same time, it is necessary to transfer large volumes of data through global networks in a timely manner without losing data integrity, so JADC2 networks must be ready for cyber attacks. To solve these problems, it is necessary to switch from existing conventional radio communication networks to high-speed broadband, including MANET mesh networks (Mobile Ad hoc Network). The main advantages of MANET networks are: deployment speed, low cost with high efficiency, the ability to transmit data over long distances without increasing the transmitter power, resistance to changes in the network infrastructure, the ability to quickly reconfigure in adverse interference conditions. Routing protocols in such networks are the most effective means of solving the problem of service quality. This work presents the results of evaluating the effectiveness of routing protocols in mesh networks in accordance with the requirements of the services provided.

Education outcomes of broadband expansion in Brazilian municipalities

This study analyzes the effect of local Internet speed infrastructure (backhaul) on educational outcomes. In 2008, the Brazilian government implemented an Internet expansion policy that brought broadband to more than 3000 municipalities. The policy was designed with implementation criteria that make it a natural experiment that can be investigated through a regression discontinuity design (RDD). The results suggest worsening proficiency, higher dropout and retention among students from municipalities served by more powerful backhauls, i.e., capable of supporting higher connection speeds over fiberoptic lines. These results are paralleled in the empirical literature, which predominantly indicates negative or neutral effects of Internet access on education. This study demonstrates the need for a deeper reflection on the domestic use of the Internet and its consequences on educational outcomes of school-age children and adolescents.

Through-Tubing Casing Deformation and Tubing Eccentricity Image Tool for Well-Integrity Monitoring and Plug Abandonment

Casing deformation and tubing eccentricity is a concern in the oil and gas industry for safety and operational reasons. Casing deformation or tubing eccentricity originates from various sources such as well completion, corrosion, formation swelling, collapse, and salt dome creep. It is important to implement a well-integrity surveillance program covering all casing and tubing strings for the full well life cycle from initial completion to abandonment. However, there has been no effective through-tubing logging method to evaluate the casing string for deformation and eccentricity. This paper describes a new Deformation-and-Eccentricity (DEC) tool that is based on electromagnetic technology and designed to measure casing deformation and tubing eccentricity while logging inside completion tubing. The DEC tool generates a unique compressed-and-focused magnetic field that provides an increased signal-to-noise ratio (SNR). The tool then employs an array of magnetic sensors to measure the magnetic flux density distributions azimuthally around the tool. The tool’s compressed-and-focused magnetic field is designed to (1) saturate the magnetic flux of the tubing, (2) to inject more magnetic flux into the first casing behind the tubing, and (3) to increase the signal measurement sensitivity and SNR. The sensor matrix measures flux density changes that correspond to variations in distance between tubing and casing. The high-resolution azimuthal magnetic sensor matrix delivers high-accuracy measurements that are used to image the flux density changes. A finite-element-based forward modeling and an optimized Gaussian processes regression method have been developed to process the raw logging data. The DEC tool has a built-in orientation measurement capability that is based on gyroscopes and accelerometers that are used to align the deformation and eccentricity images and index curves as well as the tubing thickness image. The tool specifications state accuracies of 1% of the eccentricity ratio and 5% of the deformation ratio in the range of casing OD up to 13.375 in. DEC technology provides an advanced answer product for through-tubing casing deformation and eccentricity measurements in downhole well-integrity and plug-abandonment applications. When combined with other well-integrity measurements such as a multifinger caliper and multipipe thickness log tool, a complete well-integrity evaluation can be achieved throughout the life cycle of a well. For example, significant casing deformation can often indicate possible damaged cement behind the casing. Other applications for the technology include locating tubing clamps for fiber-optic cables and control lines and determining the orientation of multistring tubing completions. Performances of the tool have been validated through research simulations, lab tests, and field trials. This paper includes a field case study of a deviated gas production well with tubing buckling and casing micro dogleg.

ТЕХНОЛОГИЯ МОНИТОРИНГА ПОДВИЖНОГО СОСТАВА НА ОСНОВЕ ДИСТАНЦИОННОГО АКУСТИЧЕСКОГО ЗОНДИРОВАНИЯ

The functionality of information-measuring systems for remote detection of faulty parts of the undercarriage of cars in motion is considered. The features of the use of fiber-optic cables laid along the railway tracks as sensors for detecting defects in the rolling stock and infrastructure of railway lines are evaluated. The functional features of the influence of external physical influences impact on the length of the reflected wave fiber Bragg gratings. The possibility of using remote acoustic sensing to determine defects in parts and assemblies of rolling stock while the train is in motion is shown, the possibilities of joint application of the remote acoustic sounding technology with axle counters and a wheel passage registration system are noted. An assessment of the conditions for ensuring the operability and adjustment of a distributed fiberoptic line of sensors for a railway section is proposed. A scheme for the planned placement of remote acoustic sounding devices at the training ground of the Belarusian Railways has been developed. The possibility of immediate detection of defective wheelsets with a maximum allowable value of sliders exceeding 1.0 mm, as well as a break in the side frame of a wagon bogie to prevent dangerous emergencies, has been established. A method is proposed for continuous monitoring of the technical condition of rolling stock in motion, providing increased control over the serviceability of parts and units of the rolling stock.

Distributed Fiber-Optic Sensing Enhances Flow Diagnostics in Gas Condensate Well

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 205435, “Flow Diagnostics in High-Rate Gas Condensate Well Using Distributed Fiber-Optic Sensing and Its Validation With Conventional Production Log,” by Fuad Aziz Atakishiyev, SPE, BP, and Alessandro Delfino and Cagri Cerrahoglu, Lytt, et al. The paper has not been peer reviewed. The authors describe a machine-learning (ML) approach for processing distributed-fiber-optic-sensing (DFOS) data that enables dynamic flow-profile monitoring using a fiber-optic electric-line cable deployed in a gas condensate well and compare the method with a conventional approach. DFOS technology has the potential to provide more-efficient and dynamic flow profiles compared with traditional methods, particularly in high-rate gas wells where production logs (PL) are recorded at reduced rates to avoid tool lifting. Technology and Field Introduction DFOS surface acquisition systems launch short pulses of light into an optical fiber, then receive its backscatter and convert it into physical measurements: temperature in the case of distributed temperature sensing (DTS) and acoustic intensity in the case of distributed acoustic sensing (DAS). These systems essentially turn a fiber-optic cable into a long array of thermometers (DTS) or multifrequency microphones (DAS). The DFOS systems record the backscatter signal continuously and measure at multiple points along the fiber. The major advantage of DFOS acquisition is the ability to record data throughout time at a very high sampling frequency. Unlike traditional PL tools, insights provided by DFOS offer a real-time view of changes in production without intervention. A successful trial was performed in a high-rate gas-producing well to test the quantitative inflow profiling algorithm on DFOS data. As part of the work, conventional PL data were acquired in high-rate gas production Well A01. An electric-line cable with built-in multimode and single-mode fiber-optic line was used to acquire conventional PL data. DAS and DTS data were acquired simultaneously for approximately 30 minutes while the well produced at a gas rate of approximately 70 MMscf/D. No sand-control completions were planned for Well A01 or for other wells in the field; therefore, in addition to the identification of a quantitative inflow profile, another main objective of the study was to identify intervals with sand production.

Modeling the method for determining the stimulated brillouin scattering threshold in a single-mode optical fiber

Nonlinear optical effects in optical waveguides play an important role in the development of fiber and integrated optics systems for optical communication and information processing. On the one hand, nonlinear effects impose restrictions on the radiation power that can be transmitted through an optical fiber or light guide. In this paper, the problem of the occurrence of the phenomenon from the stimulated Brillouin scattering (SBS) effect is investigated using two optical sources of rays in a single-mode optical fiber at joint waves of 1310 nm and 1550 nm. Due to the fact that in all trunk fiber-optic lines, the intensity and energy of input signals is limited due to the influence of SBS, methods are currently being sought to reduce the influence of this phenomenon. It was found that the energy of the input beam in the combined propagation of the compound did not reach the value of the threshold of SBS in the values of 25 dBm and 27 dBm due to the discrepancy between the experimental results and the results of the model. The SBS effect was not observed when the threshold threshold of 15 dBm and 27 dBm – SBS was reached when combining a dual beam along a single optical fiber in one direction. As a result, by double integration, the value of the SBS threshold was raised, and the direction for future scientific research was determined. If the possibility of increasing the threshold of SBS is proved, then increasing the distance of amplifiers in the main networks, respectively, its economic effect increases. In addition, it can be noted that there are no scientific papers devoted to the study of the effects of optical nonlinear effects by combining and distributing these two compounds along a single optical fiber. This article discusses the issues of improving the capacity and determination of the threshold for stimulated Brillouin scattering. To increase the power threshold is invited to consider the dependence of the phase modulation frequency of the spectral width of the laser radiation. In addition, the fact that the SBS threshold did not reach the value at an energy of 27 DB in the case of the double-beam distribution can be proved by discrepancies in comparison with the results of experimental studies and the results of the model that determines the SBS effect

Options for connecting fiber optic communication lines to the group ground cable

Options for connecting fiber optic communication lines to the group ground cable

Reflectometric temperature measurement using a single-mode-multimode-single-mode" fiber optic structure

It is shown the "single-mode-multimode-single-mode" structure allows carrying out remote temperature measurement with optical time domain reflectometer. A multimode fiber length was 10 mm. We used the temperature range from 30 to 70oC and wavelengths of 1310 and 1550 nm. The total length of a single-mode fiber-optic line for reflectometric measurements was 20 km. Keywords: fiber optics, fiber optic sensors, optical fiber reflectometry, multimode interference.

Рефлектометрическое измерение температуры с использованием оптоволоконной структуры одномод-многомод-одномод"

It is shown the "single-mode-multimode-single-mode" structure allows carrying out remote temperature measurement with optical time domain reflectometer. A multimode fiber length was 10 mm. We used the temperature range from 30 to 70oC and wavelengths of 1310 and 1550 nm. The total length of a single-mode fiber-optic line for reflectometric measurements was 20 km.

CHROMATIC DISPERSION COMPENSATION IN EXISTING FIBER OPTIC TELECOMMUNICATION LINES WITH THE GROWING BIT RATES NEEDS OF DWDM SYSTEM

The article presents an analysis of the methods of chromatic dispersion compensation in the existing, already built fiber optic telecommunications lines, based on ITU G.652 A and B fibers with the constantly growing demand for bit rates in DWDM systems. Due to the enormous investment costs, it is impossible to replace the cables used with NZDSF, hence the chapter analyzes methods of improving the bandwidth without replacing all cables. Typical models of the optimization of chromatic dispersion in the existing lines are presented.

DETERMINATION OF THE OPTICAL TRANSMITTER MODULATION TRANSMISSION FUNCTION IN THE PRESENCE OF LASERS EMITTER

The most acceptable form of transmission of information over the fiber-optic line is its encoding in the form of rectangular pulses. In most cases, a semiconductor laser diode is used as a radiation source, and a single-mode fiber is used as a light guide. The main cause of energy losses in this node is the mismatch of the apertures of the laser diode and the fiber used to propagate the signal. In fiber-optic information systems, where the signal is modulated by the supply voltage, it is important not only to reduce energy losses, but also to transmit the signal to the fiber with minimal distortion. The most effective means of estimating the effect of the optical system of input of radiation into the optical fiber on the degree of distortion of the transformed signal is the use of Fourier transform of the signal with subsequent analysis of its frequency characteristics. Considering the node of the optical transmitter as one of the links of fiber-optic information systems, we conclude that it is necessary to study its frequency characteristics, namely its modulation transmission function. The modulation transfer function of this node depends on the design parameters of the input system. Errors in basing the radiating plane of the laser diode relative to the cardinal points of the optical system for inputting radiation into the optical fiber also have a significant effect on the modulation transmission function. Such errors include defocusing and angular and transverse decentering. Calculations of aberrations with subsequent determination of the scattering function and the use of fast Fourier transform for the calculation of FPM, as well as the calculation of FPM were performed using the program ZEMAX. The research allowed to obtain results characterizing the frequency properties of a typical optical system of laser diode radiation input into a single-mode optical fiber. It is established that the most stringent requirements (at the level of several microns) should be set before the possible defocusing of the radiating plane. Possible transverse decentering is limited to ten fractions of a millimeter, and ultimately its value is determined by the allowable vignetting of the radiation flux.

INVESTIGATION OF ADDITIONAL LOSSES OF FIBER-OPTIC CONDUCTORS OF TYPE G-652 THAT OCCUR DURING BENDING

One of the problems of modern information transmission systems is the introduction of new methods of protecting information transmitted over fiber-optic transmission lines. Currently, new methods of unauthorized access are emerging, which are being improved and developed every year. Within the framework of this work, studies of additional losses during bending of the optical fiber were carried out in order to create an automatic control system for additional losses that occur during mechanical action leading to its bending. For this purpose, practical experiments were conducted to measure losses in optical fiber with multiple bends and a computer program was created based on the data obtained. With the help of this program, it is possible to estimate additional losses in the optical fiber when the wavelength changes from 1310 to 1625 nm and the bending angle indicators from 45 to 135 degrees. The program also allows you to automatically approximate the values of additional losses occurring in the optical fiber with different variations of different bending angles and their number. The study of additional losses will allow in the future to develop an automatic control system based on changes in the indicators of additional losses and, when they change, issue a warning signal about possible unauthorized connection to a fiber-optic cable.

Komodo National Park fiber optic network design and analysis by considering earthquake epicenter

Labuan Bajo and Komodo National Park (KNP) are the government's agendas in the tourism sector by making the area a premium tourist destination. On that basis, the tourism potential of the region requires infrastructure development to support this plan. One of the critical infrastructures is telecommunications, where the region does not have a direct fiber-optic line. In this paper, the authors propose two scenarios design of fiber-optic networks that also consider the potential for an upward fault earthquake in the northern waters of Labuan Bajo and KNP. The design is analyzed using calculation results of the power link budget, rise time, bit error rate (BER), and Signal to Noise Ratio. The BER value obtained is 5.63 x 10-13, which is still below the parameter threshold of 10-12 with a design that avoids the epicenter of the disaster and a longer route. The SNR value on the longest route (route 7) is 34.69 dB. The SNR value has met the SNR standard, which is 21.5 dB.