Fiber Optics Structural Mechanics: Attributes and Review

Of all the lasers in use today, it is only the semiconductor laser where the quantum noise, inevitable in all lasers, is of major practical concern. This is due to two reasons. The first one is that since semiconductor lasers have a very small physical volume, the cavity quality factor is very small, which results, according the the Schalow-Townes formula, in a large spectral width of the laser output. The second reason is that due to the widespread application of semiconductor lasers in real-life optical fiber comunications systems, the noise aspects are of real concern. The basic physical mechanism of this noise is the addition of spontaneous emission power to the laser field. This effect is compounded and amplified by coupling between intensity and phase fluctuations, which are characteristic of semiconductor lasers. In the talk we will review those physical effects and show some possible ways of reducing the laser linewidth. These ways include the use of large external cavity and/or coupling of frequency dependent loss mechanism into the laser oscillators. The effect of spontaneous emission is also a limiting factor in optical fiber amplifier systems, which are assuming major practical importance. In this case the major noise mechanism is beating between the signal propagating in the fiber and the background amplified spontaneous emission power. The basic limitation on signal to noise ratio in a practical system because of this mechanism will be reviewed. Experiments performed in various laboratories will be discussed and compared to the theory. A limiting noise behavior of the optical amplifier fiber system is shown to consist of a transmission system with uniformly distributed gain along the whole length of the fiber. The penalty factors for using other schemes of optical fiber amplification compared to the ideal system will be discussed. The last mechanism to be discussed will be that of double Rayleigh scattering in fibers. This converts phase noise to intensity noise. The resulting limiting RIN will be discussed and compared with new experiments.

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The aim of this study is to verify the possibility of detecting oil in the bottom sediment using a fibre optic system. The presence of oil is assessed on excitation-emission spectra obtained from spectral fluorescence signals of the sediment sample. A factory spectrofluorometer coupled with an experimental fibre optic measurement system was used. During the determination of spectra, the fibre optic system is set at a 45° angle to the sediment surface and placed above its surface. The light exciting the fluorescence and the light emitted by the sediment are transmitted in a combined bundle of fibre optic threads. The analysis of excitation-emission spectra of sediments contaminated with oil shows variability of the shapes of fluorescence spectra depending on the type and degree of oil contamination, which indicates the feasibility of the sensor design for detecting oil in the sediment in situ.

Волоконно-оптичні системи є одним з найбільш перспективних напрямків при розробці фізичної основи інформаційного простору. При реалізації оптоволоконних ліній зв'язку часто виникає необхідність узгодження оптоелектронних компонентів з різними поперечними перетинами випромінюючих і приймаючих областей і різними числовими апертурами. Варіантом такого завдання може бути з'єднання одномодового і багатомодового волокон або випромінювачів і фотоприймачів з волокнами різних типів. Одним з методів такого узгодження є створення каскадних волокон, в яких лінзове волокно і кілька ділянок градієнтних волокон інтегровано в одномодове волокно. Предметом дослідження є технології елементів волоконно-оптичних систем передачі. Метою даної роботи є створення компонентів волоконно-оптичних ліній зв’язку, що дозволяють підвищувати ефективність вводу випромінювання від джерела в оптичних світловод, зокрема одномодовий. Для досягнення поставленої мети необхідно вирішення наступних завдань: розглянути фактори, що впливають на втрати енергії при генерації і вводу випромінювання джерела в оптичне волокно, а також розробити і впровадити систему узгоджуючих елементів і дати послідовність дій для ефективного вводу випромінювання джерела в одномодове волокно. Висновки. Запропонована технічна і технологічна реалізація процесу робить можливим вводити більшу потужність в оптоелектронні лінії передачі інформації, що підвищує ефективність вводу випромінювання до 20 дБ. Визначення точності розташування сполучної площини в пристроях узгодження та взаємного розміщення випромінювачів та оптичного волокна дає можливість знизити втрати в з'єднанні до 0,1 дБ, передавати інформацію з більшою надійністю на більші відстані без регенерації і зберегти працездатність волоконно-оптичної системи в умовах впливу механічних, кліматичних і радіаційних факторів

The optical fiber has been extensively used as a sensor in some special fields. Because the optical fiber exists crackles itself and also produce the micro-crack as well as local damage, the fatigue behavior of the optical fiber become the main problem we care about. This paper presents the experimental study on the fatigue performance of bare fiber under static, dynamic and cyclic load. The corresponding fatigue life index (Stress corrosion index) n can be obtained, which are 17.14, 11.83 and 5.88, respectively. The experiment data reveal that fatigue life index is related to loading mode and is treated as the indicator of crack propagation resistance of materials. Because dynamic and cyclic loads can induce additional damage, the fatigue life declines dramatically under the same stress levels.

High-resolution acoustic imaging technology has been developed and deployed to map the downhole location and orientation of fiber optic lines in unconventional oil and gas and carbon capture wells. Fiber optic installations are long term monitoring solutions providing continuous measurement of temperature, sound, or strain. These fiber lines provide significant insight into the operation and optimization of downhole assets but require a large capital investment, typically upwards of a million dollars. By accurately mapping fiber optic lines, operators can prevent damaging or perforating through these costly systems during completion and production operations. High-resolution acoustic imaging technology allows operators to directly locate and map in-situ fiber optic systems at logging speeds up to ten times faster, with high accuracy, and more efficiently than legacy technologies by overcoming the requirement to install additional costly detection components. The unique sensor probe employs a circumferential array design, comprised of up to 512 individual elements which are electronically controlled from advanced imaging software. The integration of machine vision algorithms has led to a 100% success rate at detecting, orientating, and mapping of fiber optic lines to prevent damaging these costly and critical monitoring installations. Through a series of validation tests and field applications, this paper details how the solid-state imaging probe was used to identify the submillimetric indentations made at each fiber clamps installation. These contact points indicate the depth and phase orientation of each clamp in a well, enabling the generation of a high-resolution fiber optics system map. While legacy ultrasonic tools rely on a direct reflection principle, this novel, intra-steel imaging technology measures diffuse acoustic reflections at any point on, or inside of, the casing steel. Diffuse reflections are highly sensitive to indentations and markings on the casing surfaces; this removes the legacy-technology requirements for excessively slow logging speeds and the installation of costly steel detection bars. Following successful validation testing, this technology was field deployed and successfully located, oriented, and mapped all the fiber optic clamps ahead of perforating the casing of a carbon capture well. The platform imaged and mapped over 2,060 clamp contact points with a sub-radian azimuthal or phase resolution. In addition to this, high- resolution acoustics have shown fiber optic systems wrap around the casing circumference multiple times, highlighting the inability for fiber optic systems to be accurately installed and oriented. Using this dataset, the operator effectively executed subsequent perforation activities without damaging the fiber optic lines used to monitor the well and reservoir.

Fiber optic technology is making significant advances for use in a number of air and space platforms. Many of these applications involve integration into systems which make extensive use of optical fiber for high bandwidth signal transmission. The large signal transmission bandwidth of optical fiber has a large and positive impact on the overall weight of the cable harness. Several current air and space platforms that use fiber optic systems include commercial and military aircraft, unmanned aircraft, the International Space Station and several NASA and international space exploration systems. Substantial sources of variability may be introduced in the fiber optic connectors and termini that are designed into each piece of equipment unless the design specifications adequately identify operating and storage environments, use widely recognized standards for fiber optic cable assembly manufacturing and testing. At each development and manufacturing stage, from design through manufacturing, each type of fiber optic connector and termini may require unique fixtures for processing and inspection. Involving personnel from design through installation, together with suppliers, may help avoid significant costs for equipment and minimize or eliminate costly defects. Fiber optic technologies do not require significant power and complex electronics while allowing signal processing to be located close to the networked applications. There are many benefits of fiber optic systems for air and space applications, including minimal electromagnetic interference and environmental effects, lightweight and smaller diameter cables, greater bandwidth and the ability to be easily upgraded. This paper presents an overview of defining fiber optic system and component performance by identifying operating and storage environmental requirements, using appropriate standards to be used in fiber optic cable assembly manufacturing and inspection, interacting with component manufacturers for interoperable hardware, developing inspection methods and fixtures compliant with the selected standards and developing a quality plan that assures satisfaction of every design requirement.

Structural monitoring of built assets, performed to ensure safety, usability, and to better understand the assets' structural behaviour, is becoming common practice. One method to monitor structural behaviour is to use fibre optic systems to measure temperature and strain in structural elements. Fibre optic systems are relatively inexpensive, easy to install, versatile, and widely applicable. However, all the data acquired by monitoring systems are meaningless if they lack context within the built asset, and they are of little use if they cannot be appropriately exchanged and visualised. This paper presents an extension to the IFC data model standard for structural monitoring systems. The extension allows (1) to model structural monitoring systems, (2) to store and retrieve acquired data, and (3) to visualise the data directly on the BIM model. The James Dyson Building at the University of Cambridge is used as a case study, in which selected reinforced concrete columns, beams, and slabs have been instrumented with two types of fibre optic sensors. The case study demonstrates that the extension is able to fully describe the fibre optic monitoring system and that it can aid in its design, deployment, and further operation.

Understanding Telephone Electronics

The high-quality video signal has a wide spectrum typically. Therefore, in order to transmit such a signal over long distances through an optical cable, low-loss, low-dispersion optical fiber is required. In fiber-optic video systems, as well as in optical communication systems, standard single mode optical fibers (SSMF, standard G 652) are usually used. One of the advantages of these fibers is the ability to use CWDM in a wide spectrum (from 1270 to 1610 nm). At the same time, non-zero dispersion fiber (NZDSF, standard G 655) is more optimal near the wavelength of 1550 nm. However, as studies have shown, these optical fibers have an increased sensitivity to bending. This fact can be used to traffic interception. In WDM-system, for example, CWDM, due to nonlinear effects in fiber the part of the optical power from the working channel can enter the adjacent channels. Computer simulation of the four-wave multiplexing (FWM) effect in CWDM-system has been carried out. It is shown that fiber-optics systems with SSMF have more protection from traffic interception than systems with NZDSF. To transmit a high-confidential video signal, special techniques, such as frequency modulation, can be used, or additional noise signals can be added.KeywordsVideo systemsSecurity systemsFiber-optic cables

In the optical fiber communication system of high-speed and large capacity, the dispersion is one of the main technical indicators. The dispersion causes the light pulse broadening, so it leads to the distortion of signal transmission and BER (bit error rate). The main research is the single-mode optical fiber dispersion compensation. The design and performance of system structure on the dispersion compensation fiber communication system is accomplished by using of the optic system optical fiber communication system simulation. Through the analysis of system structure and the research of the performance of the key components of the system, the output signal waveform is simulated and the influence of the output signal waveform by the system structure and key components performance of the receiving end is compared. The design can reduce the system dispersion.

The effect of the nonlinear stress-strain relationship on the mechanical behavior of optical glass fibers

The operators of telecommunications have targeted their efforts towards realizing applications using broad band fiber optics systems in the access network. Thus, a new concept related to the implementation of fiber optic transmission systems, named FITL (Fiber In The Loop) has appeared. The fiber optic transmission systems have been extensively used for realizing the transport and intercommunication of the public telecommunication network, as well as for assuring the access to the telecommunication systems of the great corporations. Still, the segment of the residential users and small corporations did not benefit on large scale of this technology implementation. For the purpose of defining fiber optic applications, more types of architectures were conceived, like: bus, ring, star, tree. In the case of tree-like networks passive splitters (that's where the name of PON comes from -Passive Optical Network-), which reduce significantly the costs of the fiber optic access, by separating the costs of the optical electronic components. That's why the passive fiber optics architectures (PON represent a viable solution for realizing the access at the user's loop. The main types of fiber optics architectures included in this work are: FTTC (Fiber To The Curb); FTTB (Fiber To The Building); FTTH (Fiber To The Home).

Fiber optic systems are important telecommunication infrastructure for world-wide broadband networks. Wide bandwidth signal transmission with low delay is a key requirement in present day applications. Optical fibers provide enormous and unsurpassedtransmission bandwidth with negligible latency, and are now the transmission medium of choice for long distance and high data ratetransmission in telecommunication networks. This paper gives an overview of fiber optic communication systems including their keytechnologies, and also discusses their technological trend towards the next generation.

The upside down taper lens (UDTL) optical fiber ends are formed by a heating method. This new type of microlens can be used to make optical fiber connector between two fibers. In this paper, using plastic optical fiber, a single installation which are needed in the making UDTL fiber ends is described. The making method of this type plastic optical fiber end is introduced. Theoretically, using 1D heat conductor model, we analyze the forming tendency during the heating of the end of a plastic fiber. Experiments of the coupling between two plastic optical fibers with UDTL ends are given. The testing results of the connector shows that this novel optical fiber device can improve the coupling efficiency and provided a potentially inexpensive, simple and direct coupling method for fiber optic communication and fiber sensor systems.