Design Of Optical Fiber Research Articles

Design of the coaxial optical fiber for pulse repetition rate multiplication by Talbot effect

Abstract In this paper, we propose the use of a coaxial fiber as a suitable first order dispersive medium to achieve pulse repetition rate multiplication by use of the temporal Talbot effect. A design optimization of the coaxial fiber is discussed to achieve first order dispersion over a desired bandwidth. Pulse repetition rate multiplication is demonstrated by simulating the propagation of a Gaussian pulse train through the coaxial fiber using analytical expressions. The results are compared with those obtained in an ideal first order dispersive medium and by use of the conventional single mode fiber.

Design of Silica Multimode Optical Fibers with Extremely Enlarged Core Diameter for Laser-Based Multi-Gigabit Short-Range Optical Networks

This work presents an alternative fast and simple method for the design of a refractive index profile of silica multimode optical fibers (MMFs) with extremely enlarged core diameters of up to 100 µm for laser-based multi-gigabit short-range optical networks. We demonstrate some results of 100 µm core MMF graded index profile optimization performed by a proposed solution, which provides a selected mode staff differential mode delay (DMD) reduction over the “O”-band under particular launching conditions. Earlier on, a developed alternative model for a piecewise regular multimode fiber optic link operating in a few-mode regime for the computation of laser-excited optical pulse dynamics during its propagation over an irregular silica graded-index MMF with an extremely large core diameter, is utilized to estimate the potentiality of fiber optic links with the described MMFs. Here, we also present the comparison results of the simulation of 10GBase-LX optical signal transmission over 100 µm core MMFs with conventional and optimized graded-index refractive index profiles.

Improved Monitoring System for Heavy-Oil Steam-Assisted-Gravity-Drainage Wells

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 187441, “Improved Monitoring System for Heavy-Oil Steam-Assisted-Gravity-Drainage Wells,” by Christopher Baldwin, Weatherford, prepared for the 2017 SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, 8–11 October. The paper has not been peer reviewed. The complete paper provides an overview of the development of fiber-optic sensing for steam-assisted-gravity-drainage (SAGD) applications, including a review of more than 10 years of work in development and field applications in western Canada. Information provided in this paper is applicable beyond SAGD applications. The fiber-optic monitoring systems might also be used for intelligent, subsea, and unconventional wells. Introduction One area that has benefited from the unique advantages of fiber-optic sensing is thermal monitoring of SAGD wells. One particular fiber-optic technology that has proved successful in these thermal-monitoring applications is wavelength-domain multiplexing of Bragg-grating-based fiber-optic sensors. Commonly referred to as array temperature sensing (ATS), the Bragg-grating arrays can be manufactured splice-free for long-term reliability. The number of thermal sensing points can range from a few to well over 100 for a single cable. Each Bragg-grating sensing point provides a real-time, accurate measurement of temperature at that location along the wellbore. ATS systems have been used successfully to monitor the steam-injection and production processes in SAGD wells. ATS systems are capable of performing more-accurate temperature measurements and are able to resolve much smaller temperature features compared with distributed temperature sensing (DTS). Bragg-grating optical sensors not only provide temperature measurements but also can be packaged in a transducer to provide pressure and temperature (PT) also can be packaged in a transducer to provide pressure and temperature (PT) readings. The optical PT gauge is compatible with the surface instrumentation that records the ATS responses, allowing for the PT gauge to be integrated at the end of the ATS optical fiber for single-wellhead penetration, providing multiplexed DTS and PT measurements. Environmental Effects on Downhole Fiber-Optic Sensors The requirements for a successful monitoring system in SAGD applications are dictated by the harsh environments experienced downhole. In the past, the presence of hydrogen in these applications has caused issues with various fiber-optic sensing technologies. Improvements in optical-fiber design and downhole cable construction have helped to mitigate some of these issues, but any downhole monitoring system must be able to cope with the presence of hydrogen in relatively high-temperature environments.

光纤法珀压力传感系统设计与风洞初步实验

光纤法珀压力传感系统设计与风洞初步实验

Low Cost Plastic Optical Fiber Pressure Sensor Embedded in Mattress for Vital Signal Monitoring.

The aim of this paper is to report the design of a low-cost plastic optical fiber (POF) pressure sensor, embedded in a mattress. We report the design of a multipoint sensor, a cheap alternative to the most common fiber sensors. The sensor is implemented using Arduino board, standard LEDs for optical communication in POF (λ = 645 nm) and a silicon light sensor. The Super ESKA® plastic fibers were used to implement the fiber intensity sensor, arranged in a 4 × 4 matrix. During the breathing cycles, the force transmitted from the lungs to the thorax is in the order of tens of Newtons, and the respiration rate is of one breath every 2–5 s (0.2–0.5 Hz). The sensor has a resolution of force applied on a single point of 2.2–4.5%/N on the normalized voltage output, and a bandwidth of 10 Hz, it is then suitable to monitor the respiration movements. Another issue to be addressed is the presence of hysteresis over load cycles. The sensor was loaded cyclically to estimate the drift of the system, and the hysteresis was found to be negligible.

Broadband supercontinuum generation spanning 1.5–13 μm in Ge11.5As24Se64.5 based chalcogenide glass step index optical fiber

We have reported a design of a step index optical fiber in Ge11.5As24Se64.5 chalcogenide glass. The proposed design of optical fiber is analyzed using full vectorial finite element method. The structure offers a high nonlinear coefficient of 1431 W−1 km−1. Due to this high nonlinearity of the optical fiber a supercontinuum spectrum ranging from 1.5–13 μm is generated in only 10 mm long fiber by applying 50 fs laser secant pulses of 4000 W peak power at the pump wavelength of 3.1 μm. The use of femtosecond pulse laser results in the supercontinuum with high shot-to-shot coherence. Broadband mid-infrared supercontinuum generation has many applications such as in medical diagnosis, food quality control, gas sensing, telecommunication, and optical metrology etc.

Supercontinuum generation in chalcogenide layered spiral microstructured optical fiber

The layered spiral microstructured optical fiber (LS-MOF) design allows higher nonlinearities than the most common microstructured optical fibers. Here, we have chosen a highly nonlinear glass for its composition, the arsenic trisulfide, and we have determined its dispersion and nonlinear characteristics. After adjusting the fiber’s parameters, we obtained a record value for the nonlinear parameter of 50.7[Formula: see text]W[Formula: see text]m[Formula: see text], at 1.550[Formula: see text][Formula: see text]m. We have simulated light propagation under these optimized circumstances, achieving a broad supercontinuum, extending from 500[Formula: see text]nm to 3900[Formula: see text]nm, in a very short distance: 0.3[Formula: see text]mm.

Design of fused optical fiber bundle for ground based lidar receiver to profile the lower atmosphere

In this paper, we propose an optical fiber design for a wide field of view (WFOV) lidar receiver. The proposed system intends to collect aerosol backscatter and aims to profile the lower atmosphere from 8m onwards. We determined overlap function of lidar for various aperture stop diameters. As per our analysis, a fiber diameter of 21mm is required at the focus point of telescope to obtain the full overlap at 8m altitude. Since, it is impractical to realize such a large core diameter fiber of 21mm, we propose a field lens to converge the blur disk to 3mm spot size. To collect the focused beam, we propose to use a fused fiber bundle of 3.5mm diameter. The fused fiber offers extraordinary capturing efficiency and projects an effective mode capturing area of 5×10−8mm2. We present the fused fiber design details and compare its performance with hexagonal array fiber bundle.

Analytical Modeling Tool for Design of Hydrocarbon Sensitive Optical Fibers.

Pipelines are the main transportation means for oil and gas products across large distances. Due to the severe conditions they operate in, they are regularly inspected using conventional Pipeline Inspection Gages (PIGs) for corrosion damage. The motivation for researching a real-time distributed monitoring solution arose to mitigate costs and provide a proactive indication of potential failures. Fiber optic sensors with polymer claddings provide a means of detecting contact with hydrocarbons. By coating the fibers with a layer of metal similar in composition to that of the parent pipeline, corrosion of this coating may be detected when the polymer cladding underneath is exposed to the surrounding hydrocarbons contained within the pipeline. A Refractive Index (RI) change occurs in the polymer cladding causing a loss in intensity of a traveling light pulse due to a reduction in the fiber’s modal capacity. Intensity losses may be detected using Optical Time Domain Reflectometry (OTDR) while pinpointing the spatial location of the contact via time delay calculations of the back-scattered pulses. This work presents a theoretical model for the above sensing solution to provide a design tool for the fiber optic cable in the context of hydrocarbon sensing following corrosion of an external metal coating. Results are verified against the experimental data published in the literature.

Study of Optical Fiber Design Parameters in Fiber Optics Communications

Fiber optics is an important part in the telecommunication infrastructure. Large bandwidth and low attenuation are features for the fiber optics to provide gigabit transmission. Nowadays, fiber optics are used widely in long distance communication and networking to provide the required information traffic for multimedia applications. In this paper, the optical fiber structure and the operation mechanism for multimode and single modes are analyzed. The design parameters such as core radius, numerical aperture, attenuation, dispersion and information capacity for step index and graded index fibers are studied, calculated and compared for different light sources.

Innovative understanding of the duality confusion, the photovoltaic and magnetocaloric effects

Abstract Innovation in engineering requires clear understanding of physics of the concerned phenomena in any engineering application. This article gives clear scientific answers of two disturbing questions concerning fundamental phenomena in any electromagnetic system: “Is the light a flow of waves or particles?” and “Is the electric current a flow of particles or waves?” Such answers solve a puzzle in physics literature called the duality confusion and lead to innovative understandings of two interesting phenomena; the photovoltaic and magnetocaloric effects. Having such innovative understanding, it was possible to introduce in this paper verified concepts to robust designs of multijunction solar cells, optical fibers and magnetocaloric refrigerators. It was also possible to introduce a universal system of units that deletes redundancies in the SI system of units. At the end; it was shown that the results of Faraday’s experiment, known as Faraday’s effect, represent a proof of the introduced innovative understanding.

Static fatigue lifetime of optical fibers assessed using Boltzmann–Arrhenius–Zhurkov (BAZ) model

The recently suggested probabilistic design-for-reliability (PDfR) concept and particularly its physically meaningful and flexible Boltzmann–Arrhenius–Zhurkov (BAZ) model, can be effectively employed as an attractive replacement of the widely used today purely empirical and physically unsubstantiated power law relationship for assessing the static fatigue (delayed fracture) lifetime of optical silica fibers. In this analysis the BAZ model is employed to estimate the static fatigue lifetime of an optical silica fiber under the combined action of tensile loading and an elevated temperature. The PDfR concept has its experimental basis in the highly-focused and highly-cost-effective failure-oriented accelerated testing (FOAT). Accordingly, it is shown how the PDfR concept, BAZ model and FOAT data can be effectively used, when there is a need to assess the long-term tensile strength (static fatigue life) of a coated optical fiber subjected to the combined action of tensile loading and elevated temperature. Although the role of elevated humidity might be insignificant owing to the elevated temperature conditions, this role can be accounted for, if there is a need for that, as well, by using multi-parametric BAZ model. Since the principle of superposition does not work in reliability engineering, all the three stressors, namely, the elevated temperature, tensile stress and relative humidity, should be applied concurrently to the specimen under test, and their coupling, if any, should and could be considered by the FOAT based on the BAZ model. The numerical example is carried out, however, for the case when only the elevated temperature and tensile stress are applied. The results of the analysis can be employed in the design and testing of optical silica fibers.

Glass and Process Development for the Next Generation of Optical Fibers: A Review

Applications involving optical fibers have grown considerably in recent years with intense levels of research having been focused on the development of not only new generations of optical fiber materials and designs, but also on new processes for their preparation. In this paper, we review the latest developments in advanced materials for optical fibers ranging from silica, to semi-conductors, to particle-containing glasses, to chalcogenides and also in process-related innovations.

A Direct Formula for Ultra-Large Effective Area Fibers Design With Top-Hat Intensity Profile

In this paper, we present a new refractive index profile, in simple easy to use equation form, which allows the design of large mode area (LMA) single mode (SM) optical fibers with the special property of supporting “perfect top-hat” mode profiles. The few parameters of this formula define the refractive index profile of such fibers. We show the effect the parameters of the refractive index profile have on the desired mode field. By applying this direct formula, we avoid the use of complex inverse refractive index reconstruction methods, or time-consuming iterative design processes. We demonstrate this formula with a number of example designs of LMA SM optical fibers with perfect flat-top electric field profile and an effective mode area (Aeff) size that in some cases exceeds the 4800 μm 2 . We expect such LMA SM top-hat fiber design to be useful for the mitigation of non-linear effects and catastrophic optical damage, as well as for achieving uniform intensity deposition on the target (material, biological tissue, and so on) in high-power applications. The results presented here are testing the validity of the refractive index profiles for non-ideal designs so as we can determine the tolerance to manufacturing such fibers.

Design of All-Normal Dispersion Microstructured Optical Fiber on Silica Platform for Generation of Pulse-Preserving Supercontinuum Under Excitation at 1550 nm

We investigated numerically the possibility of all normal dispersion fiber design for near-infrared supercontinuum generation based on a standard air-silica microstructure. The design procedure includes finding of target dispersion profile and subsequent finding of appropriate geometrical fiber design by inverse dispersion engineering. It was shown that the tailoring of dispersion profile could increase the spectral width of generated supercontinuum while maintaining perfect spectral flatness. Conditions necessary for wide and flat supercontinuum generation as well as restrictions imposed by chosen materials were discussed. As a result of design and optimization procedure, an air-silica design was found providing normal dispersion up to $\text{3}\;\mu {\text{m}}$ . Simulation results with 10 nJ, 100 fs pulses demonstrate supercontinuum generation up to 1.3 octave; whereas pumping with 30 nJ, 100 fs pulses could provide 1.8 octavse supercontinuum.

Design of silica optical fibers with enlarged core diameter for a few-mode fiber optic links of onboard and industrial multi-Gigabit networks

This work presents alternative fast and simple method for design refractive index profile of silica multimode optical fibers (MMFs) providing effective mode bandwidth improvement under laser-based multi-Gigabit data transmission and few-mode regime operation in comparison with commercially available MMFs. Optimized profile equalizes delays of selected particular order guided modes being the main mode components of multi-Gigabit network transceiver laser excited optical signal transferred over proposed MMF in a few-mode regime. We present some results of refractive index profiles synthesis for MMFs with core diameters 50 and 100 μm under various combinations of the reference mode delay and the first iteration profile grade parameter as well as corresponding to these samples curves of differential mode delay spectral characteristics computed over “O”-band

Simulation of a long-haul fiber optic link with a two-mode optical fiber

Modern telecommunication networks approach the capacity crunch, which is associated with the so-called nonlinear Shannon limit. So, the passage to fiber optic links with few-mode optical fibers is considered as an alternative solution of the described problem concerned with high nonlinearity of conventional commercial single-mode optical fibers. Presently, various designs of few-mode optical fibers have been known, with the recently published works presenting experimental results demonstrating their potentialities for long-haul fiber optic links. A lot of models of long-haul fiber optic links with few-mode optical fibers have been developed based on which features of a few-mode optical fiber transport network were numerically simulated. This work presents the results of simulation of a 6000-km long-haul fiber optic link with a two-mode optical fiber and 100-km-per-span Erbium doped fiber optic amplifiers system under 100 Gbps DP-DQPSK data transmission. We studied the use of particular linearly polarized modes and optical vortices for signal transmission. The computation results were compared with the simulation of the same fiber optic link with a single-mode optical fiber under the identical conditions.

A preliminary verification of the floating reference measurement method for non-invasive blood glucose sensing

In the non-invasive sensing of blood glucose by near-infrared diffuse reflectance spectroscopy, the spectrum is highly susceptible to the unstable and complicated background variations from the human body and the environment. In in vitro analyses, background variations are usually corrected by the spectrum of a standard reference sample that has similar optical properties to the analyte of interest. However, it is hard to find a standard sample for the in vivo measurement. Therefore, the floating reference measurement method is proposed to enable relative measurements in vivo, where the spectra under some special source-detector distance, defined as the floating reference position, are insensitive to the changes in glucose concentration due to the absorption effect and scattering effect. Because the diffuse reflectance signals at the floating reference positions only reflect the information on background variations during the measurement, they can be used as the internal reference. In this paper, the theoretical basis of the floating reference positions in a semi-infinite turbid medium was discussed based on the steady-state diffusion equation and its analytical solutions in a semi-infinite turbid medium (under the extrapolated boundary conditions). Then, Monte-Carlo (MC) simulations and in vitro experiments based on a custom-built continuous-moving spatially resolving double-fiber NIR measurement system, configured with two types of light source, a super luminescent diode (SLD) and a super-continuum laser, were carried out to verify the existence of the floating reference position in 5%, 10% and 20% Intralipid solutions. The results showed that the simulation values of the floating reference positions are close to the theoretical results, with a maximum deviation of approximately 0.3mm in 1100–1320nm. Great differences can be observed in 1340–1400nm because the optical properties of Intralipid in this region don not satisfy the conditions of the steady-state diffusion equation. For the in vitro experiments, floating reference positions exist in 1220nm and 1320nm under two types of light source, and the results are quite close. However, the reference positions obtained from experiments are further from the light source compared with those obtained in the MC simulation. For the turbid media and the wavelengths investigated, the difference is up to 1mm. This study is important for the design of optical fibers to be applied in the floating reference measurement.

Single-mode operation in few-mode optical fibre based on resonant coupling

The design of a low-bending loss few-mode optical fibre is proposed. Low-bending loss for the fundamental mode is achieved by increasing the index contrast between the core and the cladding, and a microstructured mode filtering region is applied to filter out the higher-order modes in the fibre. Numerical results show that the fundamental mode loss is lower than 0.03 dB/turn and the high-order mode is higher than 4.4 dB/turn at the bending radius of 5 mm and 1300–1600 nm wavelength range.

Scalable waveguide design for three-level operation in Neodymium doped fiber laser.

We have constructed a double clad neodymium doped fiber laser operating on the three-level 4F3/2→4I9/2 transition. The laser has produced 11.5 W at 925 nm with 55% slope efficiency when pumped at 808 nm, comparable to the best previous results for a double-clad fiber configuration on this transition. Higher power pumping with both 808 nm and 880 nm sources resulted in an output of 27 W, albeit at lower slope efficiency. In both cases, output power was limited by available pump, indicating the potential for further power scaling. To suppress the stronger four-level 4F3/2→4I11/2 transition we developed a waveguide that provides spectral filtering distributed along the length of the fiber, based on an all-solid micro-structured optical fiber design, with resonant inclusions creating a leakage path to the cladding. The waveguide supports large mode areas and provides strong suppression at selectable wavelength bands, thus easing the restrictions on core and cladding sizes that limited power scaling of previous approaches.