Fibre Optic Method for Detecting Oil Fluorescence in Marine Sediments.

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.

A fibre optic multi-component seismic acquisition system for permanent installation on the sea floor has been developed and tested. Permanent seafloor seismic installations are an alternative to other marine seismic acquisition methods for time-lapse (or 4D) seismic reservoir monitoring. 4D seismic can assist reservoir engineers to monitor fluid injection and drainage of the reservoir, and help determine detailed reservoir fluid-flow models. The new fibre optic system uses a Dense Wavelength Division Multiplexing telemetry scheme to optically power the seismic sensors. This methodology allows for channel counts in excess of 2000 per cable. Furthermore, the fibre optic system has a very broad processing bandwidth that yields exceptional dynamic range (> 140dB), which together with low channel crosstalk and distortion, will produce high quality seismic images. The multi-component sensors at each receiver station are optical transducers made using Michelson interferometers. Avoiding in-sea electronics creates a safe and robust system, and utilisation of standard telecommunication components ensures an economically viable reservoir monitoring tool. Field trials conducted in hydrocarbon provinces demonstrate the reliability and excellent response of the fibre optic system to the seismic source. The seismic data acquired by the new fibre optic acquisition system show good correlation with data acquired in parallel using a conventional electrical seafloor acquisition system.

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

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

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 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

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.

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).

The electronic Permanent Downhole Gauges (PDHG) has traditionally been used in the Karachaganak field to monitor downhole pressures and temperatures, for reservoir management. The overall performance and quality of the data from some of the Permanent Downhole Gauges (PDHG) installed in the Karachaganak field was not satisfactory. Hence, fibre optics has been investigated as an alternative technology due to the reliability, calibration and cost concerns related directly to the Permanent Downhole Gauges (PDHG). This paper will discuss the implementation and installation of the first fibre optic pressure and temperature monitoring system installed in the Karachaganak field. A dual fibre optic pressure and temperature system (rated to 200°C and 20Kpsi) was installed to a depth of approximately 5000m with a maximum inclination of about 35°. The metallurgy for the fibre optics system was Inconel 718 due to the presence of H2S. The surface equipment comprised of a Zone 2 rated Wellhead Data Acquisition Unit which has direct connection to the operation base providing ‘real time’ pressure and temperature updates (up to one second update rate). The paper will highlight some of the design and implementation considerations that were addressed to combat issues which had been experienced with more conventional monitoring systems such as reliability, accuracy and data communication issues. It will also describe the process that was undertaken to meet the stringent Kazakhstan Metrology requirements that are required to be obtained prior to the deployment of a subsurface measurement system. This process involved meeting the requirements for GOST-K for Safety and Quality and the Metrological Certificate which ensures that all measuring instruments are of stated accuracy and resolution and are acceptable to an accredited Institute of Metrology. It will discuss the detailed Factory Acceptance Tests (FAT) and System Integration Tests (SIT), as part of the critical planning process prior to the field installation. The paper will also cover the challenges during installation and subsequent use. The deployment data interface requirements and associated benefits during well stimulation, well testing and subsequent production will be described in full.

This paper presents the use of a novel fiber optic accelerometer system to monitor civil engineering structures in real time. This sensor system integrates the Moire fringe phenomenon with fiber optics to achieve accurate and reliable measurements. A low-cost signal processing unit implements unique algorithms to further enhance the resolution and increase the dynamic bandwidth of the sensors. There are two major benefits in using this fiber optic accelerometer system for monitoring civil engineering structures. One is its immunity to electromagnetic (EM) interference making it suitable for difficult applications in such environments involving strong EM fields, electrical spark-induced explosion risks, and cabling problems, prohibiting the use of conventional electromagnetic accelerometers. The other benefit is its ability to measure both low- and high-amplitude vibrations with a constantly high resolution without pre-setting a gain level, as usually required in a conventional accelerometer. This benefit makes the sensor system particularly useful for real-time measurement of both ambient vibration (that is often used for structural health monitoring) and strong motion. This paper presents the prototype hardware and software development, characterization tests, and applications to real-time damage assessment, demonstrating the uniquely high performance of the Moire fringe fiber optic sensor system.

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.

In this paper we investigate the nonlinear and polarization effects in optical transmission systems and its influence on transmitted pulses. The main attention is focused on fundamental description of refractive index in nonlinear birefringent environment. In general, optical fiber is nonlinear transmission medium. The mutual interaction between transmission medium and optical intensity induces changes in the refractive index resulting to nonlinear effects that can be polarization-dependent in presence of birefringence. The global effect has a significant impact on pulse propagation. The aim of this paper is to present a numerical model, which will be suitable for estimation of DGD (Differential Group Delay) parameter in nonlinear birefringence medium. The DGD is crucial for evaluation of the impact of PMD (Polarization Mode Dispersion) in high-bit-rates fiber-optic system. Our approach opens the novel opportunity for DGD estimation based on numerical model of optical pulse propagation in nonlinear birefringence medium. Numerical model is based on solving NLSE (Nonlinear Schrodinger Equation) through the SSFM (Split-Step Fourier Method). The model is compatible for various input parameters, different kinds of optical fibers and also for different types of modulation formats. The obtained results show the DGD for different system parameters (such as input power and wavelength) and for different fiber polarization characteristics (birefringence and mode coupling). The total pulse broadening is also calculated and illustrates how all degradation effects influence the performance of fiber-optic transmission system.

Assembling different materials into one optical fiber to realize multifunctional all-fiber devices is always a challenging task, mainly because the process is not compatible with current microfabrication technology. Although various devices have been proposed to achieve “all-fiber” optoelectronic functions, most of these devices cannot connect seamlessly with the mainstream optical fiber system (silica): this is a serious impairment to their further implementation in practical applications. Here, we present an integration approach that directly combines low-dimensional optoelectronic materials (CsPbBr3 nanocrystals and graphene) onto the facet of a standard silica fiber to construct a high-performance photodetector, which can detect light with a power as low as 10−11 W with photoresponsivity as high as 2×104 A/W. Moreover, it has an extraordinary light–matter interaction path beneficial to enhancing light absorption and realizing self-passivation and protection. Because of its compatibility with current established optical fiber systems, this technique could provide a highly versatile, reproducible, and low-cost method to integrate novel zero-, one-, and two-dimensional materials and deliver more sophisticated functionalities.

Currently the high cost of energy based on consumption pattern has necessitated the need for diverse and more efficient means of conveying information. One of the newest and most efficient means of information transmission is the optical fiber system especially in telecommunication industries. Here, asymmetric waveguide are highly utilized because it has proved better than planar dielectric waveguide. Waveguiding structures are needed at optical frequencies because of intrinsic atmospheric absorption and the effect of atmospheric disturbances on the propagation of visible and near infrared radiation. This paper x-rays the importance and the advantages of asymmetric planar dielectric waveguide as well as the features that make it possible for its use in such case. It also digs deep into the effect of cladding on optical fibers by using a theoretical approach to identify clearly that asymmetric planar dielectric waveguides are almost lossless means of telecommunication. Also a theoretical consideration was used to derive a condition for which mode field and cut off for both TE and TM modes are possible for such guide.