Dissertations / Theses on the topic 'Fiber optical'
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1
Richmond, Eric William. "Birefringent single-arm fiber optic enthalpimeter for catalytic reaction monitoring." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-07282008-135248/.
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Kuhlmey, Boris T. "Theoretical and numerical investigation of the physics of microstructured optical fibres." Connect to full text, 2004. http://setis.library.usyd.edu.au/adt/public_html/adt-NU/public/adt-NU20040715.171105.
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Thesis (Ph. D.)--School of Physics, Faculty of Science, University of Sydney, 2004. (In conjunction with: Université de Droit, d'Économie et des Sciences d'Aix-Marseille (Aix Marseille III)).Bibliography: leaves 196-204.
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Srinivas, K. T. "Axial strain effects on optical fiber mode patterns." Thesis, This resource online, 1987. http://scholar.lib.vt.edu/theses/available/etd-04122010-083554/.
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Polley, Arup. "High performance multimode fiber systems a comprehensive approach /." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/31699.
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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.Committee Chair: Ralph, Stephen; Committee Member: Barry, John; Committee Member: Chang, G. K.; Committee Member: Cressler, John D.; Committee Member: Trebino. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Hao, Miin-Jong. "Performance evaluation of practival FSK, CPFSK, and ASK detection schemes for coherent optical fiber communication systems." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/15686.
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Paye, Corey. "An Analysis of W-fibers and W-type Fiber Polarizers." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/32474.
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Optical fibers provide the means for transmitting large amounts of data from one
place to another and are used in high precision sensors. It is important to have a good
understanding of the fundamental properties of these devices to continue to improve their
applications.
A specially type of optical fiber known as a W-fiber has some desirable properties
and unique characteristics not found in matched-cladding fibers. A properly designed W-
fiber supports a fundamental mode with a finite cutoff wavelength. At discrete
wavelengths longer than cutoff, the fundamental mode experiences large amounts of loss.
The mechanism for loss can be described in terms of interaction between the fiberâ ¢s
supermodes and the lossy interface at the fiberâ ¢s surface. Experiments and computer
simulations support this model of W-fibers.
The property of a finite cutoff wavelength can be used to develop various fiber
devices. Under consideration here is the fiber polarizer. The fiber polarizer produces an
output that is linearly polarized along one of the fiberâ ¢s principal axes. Some of the
polarizer properties can be understood from the study of W-fibers.Master of Science
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Lyyttkäinen, Katja Johanna. "Control of complex structural geometry in optical fibre drawing /." Connect to full text, 2004. http://setis.library.usyd.edu.au/adt/public_html/adt-NU/public/adt-NU20041011.120247.
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Lyytikäinen, Katja Johanna. "Control of complex structural geometry in optical fibre drawing." Connect to full text, 2004. http://hdl.handle.net/2123/597.
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Thesis (Ph. D.)--University of Sydney, 2004.Title from title screen (viewed 14 May 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Physics, Faculty of Science. Includes bibliographical references. Also available in print form.
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Kominsky, Daniel. "Development of Random Hole Optical Fiber and Crucible Technique Optical Fibers." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/28949.
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This dissertation reports the development of two new categories of optical fibers. These are the Random Hole Optical Fiber (RHOF) and the Crucible Technique Hybrid Fiber (CTF). The RHOF is a new class of microstructure fiber which possesses air holes which vary in diameter and location along the length of the fiber. Unlike all prior microstructure fibers, these RHOF do not have continuous air holes which extend throughout the fiber. The CTF is a method for incorporating glasses with vastly differing thermal properties into a single optical fiber. Each of these two classes of fiber brings a new set of optical characteristics into being. The RHOF exhibit many of the same guidance properties as the previously researched microstructure fibers, such as reduced mode counts in a large area core. CTF fibers show great promise for integrating core materials with extremely high levels of nonlinearity or gain. The initial goal of this work was to combine the two techniques to form a fiber with exceedingly high efficiency of nonlinear interactions.
Numerous methods have been endeavored in the attempt to achieve the fabrication of the RHOF. Some of the methods include the use of sol-gel glass, microbubbles, various silica powders, and silica powders with the incorporation of gas producing agents. Through careful balancing of the competing forces of surface tension and internal pressure it has been possible to produce an optical fiber which guides light successfully.
The optical loss of these fibers depends strongly on the geometrical arrangement of the air holes. Fibers with a higher number of smaller holes possess a markedly lower attenuation. RHOF also possess, to at least some degree the reduced mode number which has been extensively reported in the past for ordered hole fibers. Remarkably, the RHOF are also inherently pressure sensitive. When force is applied to an RHOF either isotropically, or on an axis perpendicular to the length of the fiber, a wavelength dependent loss is observed. This loss does not come with a corresponding response to temperature, rendering the RHOF highly anomalous in the area of fiber optic sensing techniques. Furthermore an ordered hole fiber was also tested to determine that this was not merely a hitherto undisclosed property of all microstructure fibers.
Crucible technique fibers have also been fabricated by constructing an extremely thick walled silica tube, which is sealed at the bottom. A piece of the glass that is desired for the core (such as Lead Indium Phosphate) is inserted into the hole which is in the center of the tube. The preform is then drawn on an fiber draw tower, resulting in a fiber with a core consisting of a material which has a coefficient of thermal expansion (CTE) or a melting temperature (Tm) which is not commonly compatible with those of silica.Ph. D.
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Robinson, Risa J. "Polarization modulation and splicing techniques for stressed birefringent fiber /." Online version of thesis, 1995. http://hdl.handle.net/1850/12228.
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Washburn, Brian Richard. "Dispersion and nonlinearities associated with supercontinuum generation in microstructure fibers." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/30964.
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Lee, Shiao-Chiu. "Axial offset effects upon optical fiber sensor and splice performance." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/91128.
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A kind of intensity modulated fiber sensor utilizing axial offset parameter is proposed. The theoretical analysis and experimental characteristics of this sensor are described.
All the theoretical results derived in this thesis are based on assuming a uniform power distribution in the fibers. An expression of coupling efficiency of central dipped parabolic graded index fibers due to axial offset is derived. The results show less sensitivity to axial offset for the central dipped fibers than for the parabolic profile fibers without a dip. Expressions of coupling efficiency of graded index fibers due to axial offset for several different values of a are also derived. The results show that sensitivity increases as the value of a decreases. A general expression of coupling efficiency which is valid for small values of axial offset is derived. This expression exhibits a linear relationship between coupling efficiency and small axial offset.
Coupling efficiencies versus fiber end separation and axial offset of step index fibers have been measured. The measurements show that coupling efficiency is much more sensitive to axial offset than end separation. A simple construction of the axial offset fiber sensor is described. An approximate linear relationship between the output power and the mechanical loading has been obtained for this sensor. Several ways of increasing the sensitivity of this sensor are discussed.M.S.
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Males, Mladen. "Suppression of transient gain excursions in an erbium-doped fibre amplifier /." Connect to this title, 2006. http://theses.library.uwa.edu.au/adt-WU2007.0157.
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Haskell, Adam Benjamin. "A Durability and Utility Analysis of EFPI Fiber Optic Strain Sensors Embedded in Composite Materials for Structural Health Monitoring." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/HaskellAB2006.pdf.
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Feth, Shari. "Sapphire optical fiber sensors." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-12232009-020350/.
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Derrington, Dolores Cormack. "Overview of fiber optics technology: industrial and military." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/43896.
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Fiber optics technology is being used in many applications, both in
the military world and in the industrial world. A broad overview of
this technology is provided, including a discussion of the fundamentals
of fiber operation and component characteristics.
Applications of fiber optics in both military and industrial
communities is addressed, identifying specific examples in both cases.
In addition, market projections and technology trends are discussed for
both the military and industrial communities.Master of Science
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Smith, Kevin H. "In-fiber Optical Devices Based on D-fiber." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/291.
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This dissertation presents the fabrication and analysis of in-fiber devices based on elliptical core D-shaped optical fiber. Devices created inside optical fibers are attractive for a variety of reasons including low loss, high efficiency, self-alignment, light weight, multiplexibility, and resistance to electromagnetic interference. This work details how D-fiber can be used as a platform for a variety of devices and describes the creation and performance of two of these devices: an in-fiber polymer waveguide and a surface relief fiber Bragg grating. In D-fiber the core is very close to the flat side of the ‘D’ shape. This proximity allows access to the fields in the fiber core by removal of the cladding above the core. The D-fiber we use also has an elliptical core, allowing for the creation of polarimetric devices. This work describes two different etch processes using hydrofluoric acid (HF) to remove the fiber cladding and core. For the creation of devices in the fiber core, the core is partially removed and replaced with another material possessing the required optical properties. For devices which interact with the evanescent field, cladding removal is terminated before acid breaches the core. Etching fibers prepares them for use in the creation of in-fiber devices. Materials are placed into the groove left when the core of a fiber is partially removed to form a hybrid waveguide in which light is guided by both the leftover core and the inserted material. These in-fiber polymer waveguides have insertion loss less than 2 dB and can potentially be the basis for a number of electro-optic devices or sensors. A polarimetric temperature sensor demonstrates the feasibility of the core replacement method. This work also describes the creation of a surface relief fiber Bragg gratings (SR-FBGs) in the cladding above the core of the fiber. Because it is etched into the surface topography of the fiber, a SR-FBG can operate at much higher temperatures than a standard FBG, up to at least 1100 degrees Celsius. The performance of a SR-FBG is demonstrated in temperature sensing at high temperatures, and as a strain sensor.
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Jackson, James Trent. "Reduction of EDFA optical power transients using power shaping." Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/jackson/JacksonJ0808.pdf.
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Many erbium doped fiber amplifier (EDFA) based multi-wavelength optical networks employ techniques such as burst-switching or packet switching where the time interval between traffic blocks can be long enough to induce EDFA optical power transients. The optical power transients are created by abrupt changes in the average input power to the EDFAs and can adversely affect the performance of the network. To mitigate the effects of EDFA optical power transients on optical networks, a method called power shaping where heads and tails are joined to the beginning and end of a traffic block is investigated. A head (tail) gradually increases (decreases) the channel power by employing a bit sequence in which the probability of a \"1\" (\"0\") increases from 0 to 0.5. Theoretical and experimental results both show that EDFA optical power transients can be significantly reduced with adequate shaping periods. Experiments also show the bit error rate of the system is reduced for increased shaping periods. Power shaping is an economical means of suppressing EDFA optical power transients compared to other physical layer approaches that require the addition of specialized components and can be applied to EDFAs as well as other solid-state and Raman optical amplifiers.
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Hattori, Haroldo Takashi. "Low Nonlinearity Optical Fibers for Broadband and Long-Distance Communications." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/29816.
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A class of low nonlinearity dispersion-shifted and dispersion-flattened fibers for
broadband and long haul applications is presented. The refractive index profiles of these
fibers assume a depressed-core multi-clad geometry in order to achieve effective-areas
much larger than those in conventional optical fibers.
A systematic approach for designing large effective-area dispersion-shifted fibers, using a
reference W-index profile to initiate the design, is presented. Transmission properties,
including effective-area, mode-field-diameter, dispersion, dispersion slope, cutoff
wavelength, and bending, microbending and splice losses are evaluated for several design
examples. To ascertain that the proposed fibers can be practically fabricated, the effects
of varying fiber dimensions and indices on effective-area, mode-field-diameter and
dispersion are assessed.
It is shown that there is a trade-off between effective-area and mode-field-diameter and,
generally, larger effective-areas are associated with larger mode-field-diameters. In other
words, less signal distortion due to fiber nonlinearity (larger effective-area) is associated
with higher power loss due to bending of fiber (larger mode-field-diameter). Thus, a large
effective-area and low bending loss are conflicting requirements. A parameter Q is
defined as a performance indicator, considering effective-area and mode-field-diameter.
Dispersion-shifted single-mode fiber designs with effective-areas of 78 mm
2 to 210 mm2 and the corresponding mode-field-diameter of 8.94 mm to 14.94 mm,
dispersion less than 0.07 ps/nm.km, and dispersion slope of about 0.05 ps/ nm2.km are
presented. Numerical simulations for propagation of pulses in few designed fibers are
performed.Designs of large effective-area dispersion-flattened fibers are also presented,
for the first time we believe. These fibers provide large effective-area and low dispersion
over an extended range of wavelengths. For our design, over the wavelength range of 1.48 mm <
l < 1.58 mm, the effective-area is 75 mm2 to 100 mm2, while the dispersion remains
below 0.7 ps/nm.km.Ph. D.
20
Boiyo, Duncan Kiboi, and Romeo Gamatham. "Optimization of flexible spectrum in optical transport networks." Thesis, Nelson Mandela Metropolitan University, 2017. http://hdl.handle.net/10948/14609.
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The ever-increasing demand for broadband services by end-user devices utilising 3G/4G/LTE and the projected 5G in the last mile will require sustaining broadband supply from fibre-linked terminals. The eventual outcome of the high demand for broadband is strained optical and electronic devices. The backbone optical fibre transport systems and techniques such as dense wavelength division multiplexing (DWDM), higher modulation formats, coherent detection and signal amplification have increased both fibre capacity and spectrum efficiency. A major challenge to fibre capacity and spectrum efficiency is fibre-faults and optical impairments, network management, routing and wavelength assignment (RWA). In this study, DWDM and flexible spectrum techniques such as wavelength assignment and adjustment, wavelength conversion and switching, optical add and drop multiplexing (OADM) and bitrate variable transmission have been experimentally optimized in a laboratory testbed for short- and long-haul optical fibre networks. This work starts by experimentally optimising different transmitters, fibre-types and receivers suitable for implementing cost effective and energy efficient flexible spectrum networks. Vertical cavity surface-emitting lasers (VCSELs) and distributed feedback (DFB) lasers have been studied to provide up to 10 Gb/s per channel in 1310 nm and 1550 nm transmission windows. VCSELs provide wavelength assignment and adjustment. This work utilises the non-return-to-zero (NRZ) on-off keying (OOK) modulation technique and direct detection due to their cost and simplicity. By using positive intrinsic negative (PIN) photo-receivers with error-free BER sensitivity of -18±1 dBm at the acceptable 10-9-bit error rate (BER) threshold level, unamplified transmission distances between 6 km and 76 km have been demonstrated using G.652 and G.655 single mode fibres (SMFs). For the first time, an all optical VCSEL to VCSEL wavelength conversion, switching, transmission at the 1550 nm window and BER evaluation of a NRZ data signal is experimentally demonstrated. With VCSEL wavelength conversion and switching, wavelength adjustments to a spectrum width of 4.8 nm (600 GHz) can be achieved to provide alternative routes to signals when fibre-cuts and wavelength collision occurs therefore enhancing signal continuity. This work also demonstrates a technique of removing and adding a wavelength in a bundle of DWDM and flexible channels using an OADM. This has been implemented using a VCSEL and a fibre Bragg grating (FBG) providing a wavelength isolation ratio of 31.4 dB and ~0.3 𝑑𝐵 add/drop penalty of 8.5 Gb/s signal. As a result, an OADM improves spectrum efficiency by offering wavelength re-use. Optical impairments such as crosstalk, chromatic dispersion (CD) and effects of polarization mode dispersion (PMD) have been experimentally investigated and mitigated. This work showed that crosstalk penalty increased with fibre-length, bitrate, interfering signal power and reduced channel spacing and as a result, a crosstalk-penalty trade-off is required. Effects of CD on a transmitted 10 Gb/s signal were also investigated and its mitigation techniques used to increase the fibre-reach. This work uses the negative dispersion fibres to mitigate the accumulated dispersion over the distance of transmission. A 5 dB sensitivity improvement is reported for an unamplified 76 km using DFB transmitters and combination of NZDSF true-wave reduced slope (TW-RS) and submarine reduced slope (TW-SRS) with + and – dispersion coefficients respectively. We have also demonstrated up to 52 km 10 Gb/s per channel VCSEL-based transmission and reduced net dispersion. Experimental demonstration of forward Raman amplification has achieved a 4.7 dB on-off gain distributed over a 4.8 nm spectral width and a 1.7 dB improvement of receiver sensitivity in Raman-aided 10 Gb/s per wavelength VCSEL transmission. Finally, 4.25-10 Gb/s PON-based point to point (P2P) and point to multipoint (P2MP) broadcast transmission have been experimentally demonstrated. A 10 Gb/s with a 1:8 passive splitter incurred a 3.7 dB penalty for a 24.7 km fibre-link. In summary, this work has demonstrated cost effective and energy efficient potential flexible spectrum techniques for high speed signal transmission. With the optimized network parameters, flexible spectrum is therefore relevant in short-reach, metro-access and long-haul applications for national broadband networks and the Square Kilometre Array (SKA) fibre-based signal and data transmission.
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Tian, Zhaobing. "Novel optical fiber devices for emerging optical applications." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114472.
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With dramatically increasing internet bandwidth, electrons as information carriers are being continually replaced with photons. This exchange has been fully completed in the long-haul high-speed backbone network, now occurs in short-reach data centers and radio frequency communications, and eventually will reach the chip level. Various emerging optical technologies have been developed during this time; with performance and cost being the two major factors to be considered for these technologies. In this work, we propose and design several novel optical fiber devices to enhance the performance or lower the associated cost of emerging technologies in the areas of microcavities and dual-mode fibers. Self-rolled-up semiconductor microtubes have been very promising in integrated optical circuits due to their unique fabrication method and their smooth surfaces. In spite of extensive study on various materials and applications, the properties of these microtubes at telecom wavelengths have not been explored. We propose and demonstrate a fiber-based solution to obtain precise single device transfer, the highest Q-factor (1.5×105) measurement, selective polarization excitation, optical-optical modulation, and the thermal dynamic effect of these microtubes. The microtubes exhibit ideal optical performance at telecom wavelengths and are a good microcavity candidate for integration with silicon photonics.Compared to semiconductor microcavities, optical fiber microcavities have the advantages of a single device fabrication process, ultra smooth surface, and easy characterization with fiber optics. The microcavities have been reported in the shapes of spheres, bottles, and bubbles. Here we propose and demonstrate a novel optical fiber microdisk with a small free spectral range and a small mode cross section. The Q-factor of the microdisk is 7.8×106 and it is demonstrated as a narrow reflection mirror in a fiber ring laser. This microdisk would be of great interest for optical nonlinear applications. We propose three optical fiber devices for dual-mode fiber emerging technologies. First, we design an in-line Mach-Zehnder interferometer by offset splicing a length of dual-mode fiber with two regular single-mode fibers. This interferometer has been successfully applied for picoseconds flat-top pulse generation. Secondly, we propose and demonstrate a mode multiplexer consisting of a LP11 mode spatial rotator and a LP01/LP11 mode coupler. This mode multiplexer can be used in both short-reach data centers and long-haul mode division multiplexing. Thirdly, we propose a fiber coupler enabling conversion of a phase modulation to a mode modulation, which could lead to low cost ultra-wide band signal generation, novel advanced modulation formats, and optical switching.Avec les bandes passantes Internet qui augmentent considérablement, les électrons sont continuellement remplacées par des photons comme porteurs d'information. Cet échange, qui a été entièrement effectué dans le réseau fédérateur long-courrier à grande vitesse, se produit maintenant dans les centres de données de courte portée ainsi que pour les communications par fréquences radio et finiront par atteindre le niveau de la puce. Diverses nouvelles technologies optiques ont été développées durant cette période et la performance et le coût sont les deux principaux facteurs à prendre en considération pour ces technologies. Dans cette thèse, nous proposons et concevons plusieurs nouveaux dispositifs à fibres optiques pour améliorer la performance et réduire le coût des technologies émergentes dans les domaines des micro-cavités et des fibres bimodales.Les microtubes semi-conducteurs enroulés sur eux-même ont été très prometteurs dans les circuits optiques intégrés en raison de leur procédé de fabrication unique et de leurs surfaces lisses. En dépit d'une étude approfondie sur les différents matériaux et applications, les propriétés de ces microtubes n'ont pas été explorées pour les longueurs d'onde des télécommunications. Nous proposons et démontrons une solution avec fibres optiques pour obtenir le transfert précis d'un seul dispositif, la plus haut mesure de facteur Q (1.5 × 105), l'excitation d'une polarisation sélective, la modulation optique et l'effet thermique dynamique de ces microtubes. Les microtubes présentent des performances optiques idéales aux longueurs d'onde des télécommunications et sont de bons candidats pour l'intégration avec la photonique sur silicium.Par rapport aux microcavités semi-conductrices, les microcavités à fibres optiques ont l'avantage de posséder un procédé de fabrication pour un seul dispositif, d'avoir une surface ultra-lisse et d'être faciles à caractériser avec une fibre optique. Les microcavités ont été signalées sous les formes de sphères, de bouteilles et de bulles. Ici, nous proposons et démontrons une nouvelle fibre optique en forme de microdisque avec un petit intervalle spectral libre et un profil d'intensité étroit. Le facteur Q du microdisque est 7.8 × 106 et il est indiqué comme un miroir de réflexion étroit dans un laser à fibre en anneau. Ce microdisque serait d'un grand intérêt pour les applications optiques non linéaires.Nous proposons trois dispositifs à fibres optiques pour les technologies de fibres bimodales émergentes. Tout d'abord, nous concevons un filtre Mach-Zehnder par l'épissage d'une longueur de fibre bimodale entre deux fibres monomodes régulières. Cet interféromètre a été utilisé avec succès pour la génération d'impulsions picosecondes à sommet plat. Deuxièmement, nous proposons et démontrons un multiplexeur composé d'un rotateur spatial de mode LP11 et d'un coupleur de mode LP01/LP11. Ce multiplexeur de modes peut être utilisé à la fois dans les centres de données de courte portée et le multiplexage par réseau fédérateur long-courrier. Troisièmement, nous proposons un coupleur de fibres permettant une conversion de la modulation de phase à une modulation de mode, ce qui pourrait conduire à la génération de signaux à bandes ultra-large et à faibles coûts, à de nouveaux formats de modulation avancés ainsi qu'à la commutation optique.
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Wavering, Thomas A. "Optical Path Length Multiplexing of Optical Fiber Sensors." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36037.
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Optical fiber sensor multiplexing reduces cost per sensor by designing a system that minimizes the expensive system components (sources, spectrometers, etc.) needed for a set number of sensors. The market for multiplexed optical sensors is growing as fiberoptic sensors are finding application in automated factories, mines, offshore platforms, air, sea, land, and space vehicles, energy distribution systems, medical patient surveillance systems, etc. Optical path length multiplexing (OPLM) is a modification to traditional white-light interferometry techniques to multiplex extrinsic Fabry-Perot interferometers and optical path length two-mode sensors. Additionally, OPLM techniques can be used to design an optical fiber sensor to detect pressure/force/acceleration and temperature simultaneously at a single point. While power losses and operating range restrictions limit the broadscale applicability of OPLM, it provides a way to easily double or quadruple the number of sensors by modifying the demodulation algorithm. The exciting aspect of OPLM is that no additional hardware is needed to multiplex a few sensors. In this way OPLM works with conventional technology and algorithms to drastically increase their efficiency. [1]Master of Science
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Hori, Takashi, Norihiko Nishizawa, Hiroyuki Nagai, Makoto Yoshida, and Toshio Goto. "Electronically controlled high-speed wavelength-tunable femtosecond soliton pulse generation using acoustooptic modulator." IEEE, 2001. http://hdl.handle.net/2237/6768.
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Nishizawa, Norihiko, Youta Ito, and Toshio Goto. "0.78-0.90-μm wavelength-tunable femtosecond soliton pulse generation using photonic crystal fiber." IEEE, 2002. http://hdl.handle.net/2237/6769.
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Liang, Yu, and 梁羽. "Versatile photonic processor based on fiber optical parametric amplifiers." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43085362.
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Liang, Yu. "Versatile photonic processor based on fiber optical parametric amplifiers." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43085362.
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Ren, Yundong. "Specially Shaped Optical Fiber Probes: Understanding and Their Applications in Integrated Photonics, Sensing, and Microfluidics." Digital WPI, 2019. https://digitalcommons.wpi.edu/etd-dissertations/569.
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Thanks to their capability of transmitting light with low loss, optical fibers have found a wide range of applications in illumination, imaging, and telecommunication. However, since the light guided in a regular optical fiber is well confined in the core and effectively isolated from the environment, the fiber does not allow the interactions between the light and matters around it, which are critical for many sensing and actuation applications. Specially shaped optical fibers endow the guided light in optical fibers with the capability of interacting with the environment by modifying part of the fiber into a special shape, while still preserving the regular fiber’s benefit of low-loss light delivering. However, the existing specially shaped fibers have the following limitations: 1) limited light coupling efficiency between the regular optical fiber and the specially shaped optical fiber, 2) lack special shape designs that can facilitate the light-matter interactions, 3) inadequate material selections for different applications, 4) the existing fabrication setups for the specially shaped fibers have poor accessibility, repeatability, and controllability. The overall goal of this dissertation is to further the fundamental understanding of specially shaped fibers and to develop novel specially shaped fibers for different applications. In addition, the final part of this dissertation work proposed a microfluidic platform that can potentially improve the light-matter interactions of the specially shaped fibers in fluidic environments. The contributions of this dissertation work are summarized as follows: 1) An enhanced fiber tapering system for highly repeatable adiabatic tapered fiber fabrications. An enhanced fiber tapering system based on a novel heat source and an innovative monitoring method have been developed. The novel heat source is a low-cost ceramic housed electric furnace (CHEF). The innovative monitoring method is based on the frequency-domain optical transmission signal from the fiber that is being tapered. The enhanced fiber tapering system can allow highly repeatable fabrication of adiabatically tapered fibers. 2) A lossy mode resonance (LMR) sensor enabled by SnO2 coating on a novel specially shaped fiber design has been developed. The developed LMR sensor has a D-shape fiber tip with SnO2 coating. It has the capability of relative humidity and moisture sensing. The fiber-tip form factor can allow the sensor to be used like a probe and be inserted into/removed from a tight space. 3) Specially shaped tapered fibers with novel designs have been developed for integrated photonic and microfluidic applications. Two novel specially tapered fibers, the tapered fiber loop and the tapered fiber helix have been developed. The tapered fiber loop developed in this work has two superiority that differentiated itself from previous works: a) the mechanical stability of the tapered fiber loop in this work is significantly better. b) the tapered fiber loops in this work can achieve a diameter as small as 15 ?m while still have a high intrinsic optical quality factor of 32,500. The tapered fiber helix developed in this work has a 3D structure that allows it to efficiently deliver light to locations out of the plane defined by its two regular fiber arms. Applications of the tapered fiber helices in both integrated photonic device characterizations and microparticle manipulations have been demonstrated. 4) Developed an acrylic-tape hybrid microfluidic platform that can allow function reconfiguration and optical fiber integration. A low-cost, versatile microfluidic platform based on reconfigurable acrylic-tape hybrid microfluidic devices has been developed. To the best of the author’s knowledge, this is the first time that the fabrication method of sealing the acrylic channel with a reconfigurable functional tape has been demonstrated. The tape-sealing method is compatible with specially shaped fiber integrations.
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Okonkwo, Igweani Uchenna Titus. "Optical fiber transmission systems for in-door next generation broadband access network." Thesis, Brunel University, 2014. http://bura.brunel.ac.uk/handle/2438/10539.
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This thesis investigates the generation and radio-over-fibre (RoF) transport of unlicensed 60 GHz millimetre-wave (mm-wave) frequency band. The investigated benefits of transmission schemes applicable for the mm-wave generation include optical carrier suppression (OCS), optical frequency multiplication (OFM) and remote heterodyne detection (RHD). For the in-door cabling of the mm-wave transmission, a low-cost polymer optical fibre (POF) along with bend-insensitive single mode fibre (BI-SMF) has been investigated for short-range networks. Transporting mm-wave generated signals over POF and BI-SMF cables based on OCS scheme showed results with the highest spectral efficiency and least inter-symbol interference over a 2.5 Gbit/s data delivery. Based on this thesis analysis, OCS simulation of POF showed the most reliable power penalty performance and receiver sensitivity at 30-m whilst the BI-SMF fiber produced equal observations at 150-m and more. In observing the free space links of delivering the RoF signal, the attenuation on the received signal power for both POF and BI-SMF was insignificant but expected, as the simulation assumed complete and total collimation of the light beams onto the aperture of the photodetector. OCS scheme for mm-wave generation and transport was explored based on the cost effectiveness of using one external modulator compared to other generation schemes that utilised more than one external modulator. OFM scheme was simulated to transport LTE and Wi-Fi signals along with 60 GHz RF band through both SMF and MMF-POF/BI-SMF cables. OFM transport scheme produced the highest attenuation on LTE, Wi-Fi and mm-wave signals carrying 100 Mbit/s data as simulated POF lengths increased. The best performance POF length was observed at 10-m. The application of offset launch technique at the coupling of SMF and POF showed insignificant improvement on signal bandwidth. The free space OFM transmission also demonstrated negligible change to the received signal power. This reinforces the attributes of deploying OWC system in an in-door environment. In other investigation, the simulated successful delivery of mm-wave signal using RHD scheme modulated and transported 10 Gbit/s data signal over POF and BI-SMF cables. Additional observed unrecorded result also showed BI-SMF cable maintained a 2% reduction of received power for 450-m fiber cable from 150-m. The attributes to RHD includes its low operating power system application and delivery of localised 60 GHz signal for uplink RoF transmission. The conceptualised design of Gigabit data delivery for indoor customer applications either through POF or BI-SMF cable, transporting various wireless channels has been presented in this thesis for the design of a robust next generation Broadband access network to reinforce the fiber-inside-the-home (FiTH) deployment.
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Suzuki, Shigeru. "Optical Fiber Devices: Novel Fiber Lasers and Image Amplifier." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194910.
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Three fiber based optical devices: all phosphate glass fiber laser, single hybrid mode fiber laser, and fiber image amplifier, were investigated in this dissertation. Phosphate fiber Bragg grating (FBG) is desired to improve performance of recently developed high power single frequency lasers that were based on highly rare earth ion doped phosphate fibers because these lasers were fabricated with silica FBGs that have incompatible properties with standard phosphate glasses. Since standard phosphate glasses are not photosensitive, Ge-doped phosphate glasses were fabricated and their UV-photosensitivity was examined. A phosphate fiber that has Ge-doped core showed UV index changes more than ~1.1 × 10⁻³. An all-phosphate fiber laser was also demonstrated with the Ge-doped phosphate FBG. Single hybrid mode fiber laser that involves a large area mode in cavity formation was demonstrated. The fiber laser consists of an Er-doped active fiber and two FBGs. One FBG was a core-cladding mode converter, and the other FBG was a narrowband high reflector that selects the lasing wavelength and mode. This approach for designing a laser cavity provides a much larger mode area than conventional large-mode-area stepindex fibers, and is supposed to suitable for a high power fiber laser. Also this configuration allows us to make novel ring-like cavities and sensor devices that consist of higher mode of optical fibers. Image amplifier based on a highly rare earth ion doped phosphate fiber is a unique approach to overcome weakness of widely used image intensifiers that lose a lot of information in the image, such as spectral distribution, polarization, and phase. Image amplification with a 19-pixel optical image amplifier array based on high gain per unit length Yb³⁺-doped phosphate glass optical fiber was demonstrated. A 10-cm of the 19- pixel fiber image amplifier provides spatially uniform image amplification with gain of 30 dB/pixel or more. This image amplifier responds quickly to changes in the image position – with potential for GHz-level or higher frame rates. This unique approach for image amplification offers low noise, high gain, and wide field of view in a compact fiber-based device.
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Li, Qin, and 李沁. "All-fiber laser sources for fiber optical parametric amplifiers in 1 um." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47175898.
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Fiber optical parametric amplifier (FOPA) is undoubtedly one of the most thriving research topics about optical amplifiers during the past decades. The high optical gain, arbitrary gain regions and wavelength conversion with large frequency shift make FOPA outstanding in diverse application areas like the high-speed all-optical communication, wavelength-tunable laser sources and optical imaging systems. Special fiber gain medium and proper pump source are two essential elements in an FOPA setup. As the research interest on FOPAs has recently gradually extended from the conventional 1.5-_m region to the shorter wavelength band at 1 μm, photonic crystal fibers (PCFs) act as the gain media by virtue of their customized dispersion curve and nonlinearity in this band. And the 1-mum laser sources incorporating ytterbium-doped fiber (YDF) as the gain medium have been investigated as well. We prefer all-fiber laser as the pump source not only because of its high output quality but also its compatibility with other fiber systems like FOPA. However, compared with 1.5-_m range, fiber lasers in 1-_m wavelength window have not been fully developed. Most of the laser sources reported in this wavelength range are not all-fiber base. For those few all-fiber reports, the tuning range of the pulsing wavelength is not wide enough, which might limit the performance of the FOPA. In this thesis, we have investigated tunable fiber lasers aiming at becoming the promising pump sources for 1-μm FOPAs. All-fiber lasers with different techniques and operation schemes based on the YDF have been discussed.
Tunable ytterbium (Yb) fiber lasers with short pulsed output are important for pulsed-pumped FOPAs in 1 _m. Passive and active mode locking techniques are both commonly employed in short pulse generation. Passive mode-locking laser cavity usually works at the fundamental frequency of the cavity (?MHz) and has the potential to generate ultra-short pulse (? fs) due to its fast recovery time. On the other hand, active mode locking is more agile in terms of the repetition rate, which is synchronized with the external electrical signal. It can be as high as tens of GHz, which is useful for high-speed optical communication, and also can be as low as tens of MHz, which can benefit applications that require high peak power. For an all-fiber mode-locked laser based on YDF, the self-starting of the passive mode locking in 1 _m is more difficult than in 1.5 μm due to the large value of the normal material dispersion in optical fibers in this shorter wavelength range. In this thesis, we have focused on the active mode-locking cavity. Two schemes of actively mode-locked fiber lasers have be demonstrated. One is with a high repetition rate of about 10-GHz at around 1030 nm. The 30-nm tuning range is beneficial to the development of the wavelength-division multiplexing (WDM) technology in the newly developed 1-μm communication band. And on the basis of this scheme, another actively mode-locked fiber laser with a wider tuning range (almost 50 nm) have been achieved by optimizing the length of the YDF inside the cavity. Considering the applications like fiber sensing or spectroscopy where high peak power is more essential and also due to the limitation of our 980-nm pump power, the repetition rate has been lowered down to around 300 MHz in the second scheme.
Tunable continuous-wave (CW) fiber lasers in 1 _m have also been discussed. For an all-fiber ring laser cavity, a stable CW output without mode-hopping can be achieved by selecting out single frequency. Various experimental configurations have been proposed for single-longitudinal-mode (SLM) oscillation. We have combined the multiple-ring cavity (MRC) and the saturable absorber in the same fiber laser cavity to facilitate the SLM generation in 1 _m. The tunable CW SLM fiber laser has the potential to build a sweeping source with instantaneous narrow linewidth for optical coherence tomography (OCT) in this range. It can also be utilized as the pump source for CW FOPAs, which is more immune from the walk-off effect between the pulsed pump and the signal, as long as the stimulated Brillouin scattering (SBS) has been suppressed properly.published_or_final_version
Electrical and Electronic Engineering
Master
Master of Philosophy
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Atherton, Adam F. "Integrated optical fiber lattice accumulators." Monterey, California. Naval Postgraduate School, 1997. http://hdl.handle.net/10945/8542.
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Approved for public release; distribution is unlimited.Sigma-delta modulators track a signal by accumulating the error between an input signal and a feedback signal. The accumulated energy is amplitude analyzed by a comparator. The comparator output signal is fed back and subtracted from the input signal. This thesis is primarily concerned with designing accumulators for inclusion in an optical sigma-delta modulator. Fiber lattice structures with optical amplifiers are used to perform the accumulation. Two fiber lattice structures are designed, modeled, tuned, tested, and characterized. The testing results for both models are plotted and tabulated. One result is that accumulation is inversely proportional to coupling ratio. Also, the optical gain necessary to drive either fiber lattice structure to a monotonically increasing response is identical. With less than 10 (113 of optical gain, a wide range of accumulation rates are available. Initial integration of one fiber lattice structure into a first-order sigma-delta modulator is accomplished with results consistent with those from an ideal model. The design for a second-order sigma-delta modulator is developed, tested, and preliminary results shown
32
Barnes, Adam. "Sapphire fiber in optical sensors." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-09052009-041053/.
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Shapira, Ofer Ph D. Massachusetts Institute of Technology. "Optical and optoelectronic fiber devices." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40511.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 111-119).
The ability to integrate materials with disparate electrical, thermal, and optical properties into a single fiber structure enabled the realization of fiber devices with diverse and complex functionalities. Amongst those, demonstrated first in our work, are the surface-emitting fiber laser, the hollow-core fiber amplifier, the thermally self-monitored high-power transmission fiber device, and the photo-detecting fiber-web based imaging system. This work presents the design, analysis, and characterization of those devices. It opens with a study of the transmission properties of the multimode hollow-core, photonic bandgap fiber constructed of a periodic multilayer cladding. A defect is then introduced into one of the cladding layers and the interaction between core and defect modes is investigated. The second chapter addresses the experimental problem encountered in many multimode waveguide applications: how to extract, and to some extent to control, the modal content of the field at the output of a waveguide. We developed a non-interferometric approach to achieve mode decomposition based on a modified phase retrieval algorithm that can yield the complete vectorial eigenmode content of any general waveguiding structure and demonstrated its validity experimentally. In the third chapter an active material is introduced into the hollow-core to form a surface-emitting fiber laser. A unique azimuthally anisotropic optical wave front results from the interplay between the cylindrical resonator, the anisotropic gain medium, and the linearly polarized axial pump. We show that the direction and polarization of the wave front are directly controlled by the pump polarization.
(cont.) In the last two chapters, a new type of fiber is presented, constructed of semiconducting, insulating, and conducting materials, which enables the integration of semiconductor devices into the fiber structure. In the first we demonstrate a fiber comprised of an optical transmission element designed for the transport of high power radiation and multiple thermal-detecting elements encompassing the hollow core for distributed temperature monitoring and real-time failure detection. In the second, we demonstrate optical imaging using large-area, three-dimensional optical-detector arrays, built from one-dimensional photodetecting optoelectronic fibers. Lensless imaging of an object is achieved using a phase retrieval algorithm.
by Ofer Shapira.
Ph.D.
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Saleh, Walid. "In-line optical fiber holography." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/41970.
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Wang, Xingwei. "Optical Fiber Tip Pressure Sensor." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/35490.
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Miniature pressure sensors which can endure harsh environments are a highly sought after goal in industrial, medical and research fields. Microelectromechanical systems (MEMS) are the current methods to fabricate such small sensors. However, they suffer from low sensitivity and poor mechanical properties.
To fulfill the need for robust and reliable miniature pressure sensors that can operate under high temperatures, a novel type of optical fiber tip sensor only 125μm in diameter is presented in this thesis. The essential element is a piece of hollow fiber which connects the fiber end and a diaphragm to form a Fabry-Pérot cavity. The all-fused-silica structure fabricated directly on a fiber tip has little temperature dependence and can function very well with high resolution and accuracy at temperatures up to 600ï °C. In addition to its miniature size, its advantages include superior mechanical properties, biocompatibility, immunity to electromagnetic interference, disposability and cost-effective fabrication.
The principle of operation, design analysis, fabrication implementation and performance evaluation of the sensor are discussed in detail in the following chapters.
Master of Science
36
Shih, Jessica Chu-Huei. "Concentric-core optical fiber sensors." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91069.
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This thesis describes the implementation of a mechanical strain sensor which uses concentric core optical fiber waveguide as the sensing element. When this particular type of fiber is strained, a transfer of optical power occurs between propagating modes in the two concentric cylindrical cores of the fiber. This strain-induced redistribution of optical power may be detected at the output end of the fiber using either two separated optical detectors or a two dimensional detector array. The calibrated strain sensitivity of the sensor is reported and suggestions for continuing research are discussed.M.S.
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Kos, David. "Napájecí zdroj Power-Over-Fiber." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377115.
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This thesis deals with the possibilities of energy transmission by optical fiber for the purpose of powering of electronic systems. It comprises issues of electrical energy conversion to optical energy, coupling the power into the optical fiber, coupling between fiber and opto-electric transducer, conversion of optical energy to electrical energy, and transformation on required voltage levels. The principles of such Power-Over-Fiber are discussed in the first part of the work. Various technologies for the implementation of key system parts and their effectivity are discussed. In the next part, several Power-Over-Fiber commercial devices are compared. Subsequently, systems for Power-Over-Fiber experimental implementations are proposed. They are based on the utilization of semiconductor laser, multimode fiber, photovoltaic cell and related electronic circuits. The final part of the thesis deals with the construction of experimental systems and measurement of parameters of transmitted power and efficiency.
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Males, Mladen. "Suppression of transient gain excursions in an erbium-doped fibre amplifier." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0157.
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This thesis reports original work on suppression of transient gain excursions in an erbium-doped fibre amplifier (EDFA). The work presented in this thesis is a detailed investigation of four closed-loop systems that control the EDFA gain dynamically. The performance of the four closed-loop systems is evaluated by analytical work, supplemented by computer simulations and insystem measurements performed on a hardware EDFA. In addition, a stability analysis of the four closed-loop systems is presented. In the stability analysis presented in this thesis, nonlinear nature of the four closed-loop systems is taken into consideration. In the stability analysis, in addition to proving that the four closed-loop systems considered are stable, it is proven that for any practical values of the EDFA gain at the initial time of observation, the EDFA gain is restored to the desired value in steady state. These outcomes of the stability analysis are supported by simulation results and experimental results. Errors in system modelling, change in the operating point of the nonlinear closed-loop system, and measurement noise are important aspects of practical implementations of systems that control the EDFA gain dynamically. A detailed analysis of the effects these practical aspects have on the performance of the four closed-loop systems considered is presented. The analysis is validated using computer simulations and experimental measurements. In most of the work reported in the literature on controlling the EDFA gain, controllers that include feedforward and/or feedback components are employed. In the traditional approaches to combining the feedforward and the feedback components, large transient excursions of the EDFA gain can still occur due to errors in the control provided by the feedforward component. In this thesis, a novel approach to combining the feedforward and the feedback components of the controller is presented. Based on the analytical work, the computer simulations and the experimental work presented in this thesis, the novel approach provides a significant reduction in the excursions of the EDFA gain in the transient period.
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Utou, Frumence E. "Fiber optic sensors ensuring structural integrity." Thesis, Cape Peninsula University of Technology, 2005. http://hdl.handle.net/20.500.11838/1300.
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Thesis (DTech (Mechnical Engineering))--Cape Peninsula University of Technology, 2005Among the issues that are taken into consideration for many years by Engineers and Technologists is the integrity of the servicing elements in structures and mechanisms. It is a documented phenomenon that after a certain period of time, in service, engineering components tend to change their original state, and begin to develop faults and defects. This includes the original shape distortion due to effects such as bending, twisting, and cracks. The above-sited effects may be caused by the sudden or accumulative effect of overloading, thermal shocks, corrosion etc, which eventually lead to malfunction of these engineering components. The occurrence of the cracks may be as a result of stress variation in excess of different or similar materials; thermal shocks, vibration, etc. A system of structural health monitoring using optical fiber sensors to track down a crack occurrence and its propagation is considered to be a promising method in warning of catastrophic events. Taking advantage of optical fibers' properties and behavior, such as easy interaction with other materials, small size, low weight, corrosion resistance, geometrical flexibility and an inherent immunity to electromagnetic interference, there is potential in adopting the Fiber Optic Sensors (FOS) for structural health monitoring systems. Structural integrity does not confine itself to crack detection only. For example there are many instances where unwanted or excessive displacement may occur. Optical fibers play an important role in proximity sensing as evidenced in the literature [49] to [54] and available commercial systems. However it is felt that FOS displacement sensors may suffer in measurement accuracy due to in situ conditions.
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Churin, Dmitriy. "Development of Ultrafast Fiber Laser Sources." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/579113.
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The development of high average and peak power ultrashort pulsed fiber lasers is important for many critical research, industrial, and defense applications. However, the performance of mode-locked fiber oscillators still lags behind that of solid-state counterparts such as Kerr-lens mode-locked Ti:sapphire lasers. Despite the drawbacks in cost, size and required maintenance, Ti:sapphire remains the workhorse of ultrafast science. One of the remaining challenges for fiber lasers to overcome is their limited set of accessible wavelengths. Unfortunately, readily available ytterbium, erbium and thulium fiber lasers can produce coherent radiation only near 1, 1.55 and 2μm, respectively. There remain a significant number of wavelength regions that fiber lasers cannot address. In this thesis, novel fiber lasers producing ultrashort pulses at wavelengths not currently accessible with established active rare-earth-doped fibers are investigated. Our main approach is to use various nonlinear optical effects to generate new laser wavelengths. First, a watt-level synchronously pumped Raman fiber oscillator generating tens of nanojoules femtosecond pulses is demonstrated. Stimulated Raman scattering in a passive fiber within an oscillator cavity allows formation of Raman pulses that are spectrally redshifted with respect to the pump pulses. World-record output pulse energy and conversion efficiency have been achieved with our femtosecond Raman fiber laser design. We have also demonstrated a high power, widely tunable all-fiber optical parametric oscillator (FOPO) based on four-wave mixing in a passive fiber. The FOPO is synchronously pumped with an Yb³⁺-doped mode-locked fiber laser working at ~1040nm. The FOPO produces ultrashort pulses tunable from 760 to 1560nm. Record pulse energy is generated at the output of the femtosecond FOPO. Depending on the configuration of the FOPO, the duration of produced pulses varies between 170fs and 3ps. This new laser source has similar performance to standard Ti:sa femtosecond lasers so it can potentially replace the latter in many applications. Ultrashort optical pulses in the mid-IR and long-IR range (2-20 μm) have many important applications in gas sensing, counter-measures, etc. The realization of the ultrashort pulses in the mid-IR and long-IR wavelengths requires the use of free-space nonlinear crystals. An efficient mid-IR source based on difference frequency generation (DFG) in an AgGaS₂ crystal using femtosecond erbium/thulium pump fiber laser has been proposed and demonstrated. The photon conversion efficiency of the pump wave (1.55μm) to idler wave (9.2μm) has been measured to be 16%, which is today a record for conversion of near-IR light radiation from fiber lasers to 9μm spectral range. Potentially the photon conversion efficiency can be increased up to 60% by using pump pulses having higher peak power. Finally, generation of supercontinuum (SC) light in the mid-IR spectral range is also demonstrated. It is well known that SC produced in standard optical fibers is limited to ~6μm by material absorption. The liquid core optical fiber platform has been proposed to address this matter. Several highly nonlinear liquids have minimal absorption in the mid-IR wavelength range, which potentially allows us to create broadband SC light in this spectral region. SC generation up to 2.4μm in an integrated hollow core optical fiber filled with CS₂ has been demonstrated. Further development of the liquid core optical fiber platform should allow generation of the SC covering wavelengths beyond 6μm.
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Takayanagi, Jun, Norihiko Nishizawa, Hiroyuki Nagai, Makoto Yoshida, and Toshio Goto. "Generation of high-power femtosecond pulse and octave-spanning ultrabroad supercontinuum using all-fiber system." IEEE, 2005. http://hdl.handle.net/2237/6770.
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King, Branden Joel. "Tapered Optical Fiber Platform for Biosensing Applications." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1398708775.
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Jong, Yeung-dong. "Fiber-optic interferometer for high 1/f noise environments /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Flatten, Amy K. "Interaction of ultrasound with a polarization preserving optic fiber." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/30723.
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45
Fan, Chenjun. "Fiber optic sensor based on dual ring resonator system /." Online version of thesis, 1992. http://hdl.handle.net/1850/11070.
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Wang, Xie, and 王勰. "Multiwavelength optical sources based on fiber optical parametric process." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206438.
Full textAbstract:
With ever-increasing networking bandwidth demand imposed by data explosion in recent years, optical source generation plays a more and more important role in fiber optical communications. Today wavelength-division-multiplexing (WDM) which refers to encoding independent information onto different wavelengths becomes a widely used technique to increase the transmission bandwidth. However, current WDM system usually requires one single laser source for each distinct wavelength channel which is relatively expensive and cumbersome. Moreover, current WDM system is usually confined to conventional band (C-band) due to the lack of proper gain medium outside C-band. Thus simultaneously generating multiple wavelengths beyond C-band is highly desirable and attractive.
Fiber optical parametric amplifier (FOPA) which is based on χ^((3)) nonlinear effect of optical fiber exhibits remarkable properties such as high gain, wide gain bandwidth, and ultra-fast response and could act as a promising candidate for amplifying optical signal beyond C-band.
In this thesis I propose and demonstrate several multiwavelength optical sources by taking advantaging of the parametric process. I first experimentally demonstrate the dual-cavity mode-locked FOPO by utilizing two intracavity branches which share the same highly-nonlinear dispersion-shifted fiber (HNL-DSF) as gain medium. Simultaneous generation of 10-GHz pulse train at four different wavelengths located in short wavelength band (S-band) and long wavelength band (L-band) can be achieved. I then introduce the first dispersion distributed FOPO at 10-GHz. With this more advanced cavity configuration, narrower wavelength spacing and wider tuning range in the S- and L-band can be obtained more efficiently in a single cavity.
In addition to multiwavelegnth 10-GHz FOPO, multiwavelength FOPO at higher repetition rate beyond C-band is also of great interest in fiber optical communication. I then achieve the first widely tunable 40-GHz dual-wavelength pulsed FOPO. Good quality pulses in both S-and L-band with relatively short duration and low timing jitter can be generated simultaneously.
Apart from the parametric process in uniform fiber, I also explore the parametric process in dispersion oscillating fiber (DOF) whose dispersion is periodically modulated along the propagation direction. Based on quasi-phase matched parametric process in DOF, we generate two pairs (quad-wavelength) of modulation instability (MI) side lobes simultaneously. We then numerically and experimentally investigate the spectral correlation between multiple MI by leveraging the dispersive Fourier transformation method.
My research efforts presented in this thesis will show the versatility of parametric process for generating multiwavelength optical waves. These schemes have the potential to become efficient optical sources for optical communication beyond C-band.published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
47
Larson, Adam Michael. "Optical fiber based ultrashort pulse multispectral nonlinear optical microscopy." Thesis, [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2323.
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Wu, Jingwei, Xiushan Zhu, Valery Temyanko, LaComb L. Valery, R. A. Norwood, and N. Peyghambarian. "Power scaling of single-frequency fiber amplifiers at 976 nm." IEEE, 2016. http://hdl.handle.net/10150/622788.
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Cladding pumped single-frequency Yb3+-doped fiber amplifiers at 976 nm were investigated. Over 4 W output power was obtained and further power scaling can be achieved by reducing the cladding diameter of the Yb3+-doped fiber.
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Andrews, Jeffrey Pratt. "Longitudinal misalignment based strain sensor." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/43283.
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A practical fiber optic strain sensor has been developed to measure strains in the range of 0.0 to 2.0 percent strain with a resolution ranging between 10 and 100 microstrain depending on sensor design choices. This intensity based sensor measures strain by monitoring strain induced longitudinal misalignment in a novel fiber interconnection. This interconnection is created by aligning fibers within a segment of hollow core fiber. Related splice loss mechanisms are investigated for their effect on resolution. The effect of gauge length and launch conditions are also investigated.
Master of Science
50
Haakestad, Magnus W. "Optical fibers with periodic structures." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1494.
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This thesis concerns some experimental and theoretical issues in fiber optics. In particular, properties and devices based on photonic crystal fibers (PCFs) are investigated.
The work can be grouped into three parts. In the first part we use sound to control light in PCFs. The lowest order flexural acoustic mode of various PCFs is excited using an acoustic horn. The acoustic wave acts as a traveling long-period grating. This is utilized to couple light from the lowest order to the first higher order optical modes of the PCFs. Factors affecting the acoustooptic coupling bandwidth are also investigated. In particular, the effect of axial variations in acoustooptic phase-mismatch coefficient are studied.
In the second part of the thesis we use an electric field to control transmission properties of PCFs. Tunable photonic bandgap guidance is obtained by filling the holes of an initially index-guiding PCF with a nematic liquid crystal and applying an electric field. The electric field introduces a polarization-dependent change of transmission properties above a certain threshold field. By turning the applied field on/off, an electrically tunable optical switch is demonstrated.
The third part consists of two theoretical works. In the first work, we use relativistic causality, i.e. that signals cannot propagate faster than the vacuum velocity of light, to show that Kramers-Kronig relations exist for waveguides, even when material absorption is negligible in the frequency range of interest. It turns out that evanescent modes enter into the Kramers-Kronig relations as an effective loss term. The Kramers-Kronig relations are particularly simple in weakly guiding waveguides as the evanescent modes of these waveguides can be approximated by the evanescent modes of free space. In the second work we investigate dispersion properties of planar Bragg waveguides with advanced cladding structures. It is pointed out that Bragg waveguides with chirped claddings do not give dispersion characteristics significantly different from Bragg waveguides with periodic claddings.