Dissertations / Theses: 'Microstructured optical fibre'

1

Hillman, Christopher Wyndham John. "Scanning near-field optical microscope characterisation of microstructured optical fibre devices." Thesis, University of Southampton, 2002. https://eprints.soton.ac.uk/15484/.

Full text

Abstract:

This thesis details work relating to the characterisation of microstructured fibres using SPM techniques. More specifically the optical properties of the fibres have been investigated by the use of a scanning near-field optical microscope and atomic force microscopy. The SNOM was constructed and fully characterised as part of this work. The current state of research into microstructured fibre fabrication, theory and applications is currently benefitting from a great deal of interest from academia and commercial investors alike. New fibre structures are being produced at a rate previously impossible. With this increase comes a need to be able to characterise more effectively the fibres that are produced. SNOM provides a number of significant features that address this issue. In this work four recently fabricated microstructured fibres have been investigated at a number of wavelengths. In each case accurate mode pro- files have been measured and compared with resolution that would be extremely difficult to obtain with traditional mode profiling techniques. A theoretical model has also been used to predict the mode profiles. Measurements of the mode profiles after propagation in free space are presented and are compared to a theoretical beam propagation technique. An interferometric technique at 1550nm was used to image electric field amplitude and phase of the fibre modes, including results on the phase evolution of the mode as it propagates in free space.

APA, Harvard, Vancouver, ISO, and other styles

2

Caillaud, Céline. "Élaborations et caractérisations de fibres optiques microstructurées en verres de chalcogénures pour le moyen infrarouge." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S062/document.

Full text

Abstract:

Les verres de chalcogénures combinent plusieurs propriétés : une transparence étendue dans l’infrarouge, un indice de réfraction élevé (n>2) et de fortes propriétés non-linéaires. La réalisation de fibres optiques microstructurées (FOMs) permet d’exacerber les effets non-linéaires et notamment en faisant varier les paramètres optogéométriques des fibres (d et Λ). Ainsi, des fibres à propagation monomode peuvent être obtenues ou encore des fibres dont les applications potentielles concernent l’optique active avec la génération d’effets non-linéaires. La réalisation de telles fibres passent par la synthèse de verres de chalcogénures de haute pureté. Par conséquent, les bandes d’absorption limitant la transparence des fibres doivent être identifiées et limitées au maximum. Pour cela, le suivi et la qualification des éléments utilisés lors de la synthèse des verres doivent être entrepris. Un protocole de synthèse et de purification par traitements thermiques a été mis en place en ce sens. La technique pour élaborer les FOMs en verres de chalcogénures est le moulage. Elle consiste à couler un verre dans un moule entièrement réalisé en silice. Ce dernier présente la géométrie inverse de la fibre désirée. Cette méthode permet d’obtenir des géométries variées et reproductibles en passant par des fibres monomodes et multimodes avec des diamètres de cœur allant de 2 μm jusqu’à plus de 20 μm. La réalisation de sources infrarouges a été développée dans le manuscrit. Cela a été rendu possible dans un premier temps par la génération d’un supercontinuum à l’aide d’une fibre à cœur suspendu puis par la réalisation d’un laser à cascade quantique (QCL) couplé à une fibre monomode. De plus, une fibre à maintien de la polarisation (FMP) dans le moyen infrarouge, présentant une biréfringence de groupe de l’ordre de 10-3 a été élaborée grâce à l’évolution du moule de silice. De plus, un coupleur tout-optique, une fibre toute-solide et un faisceau de fibres infrarouges complètent les réalisations obtenues au cours de cette thèse
Chalcogenide glasses combine several properties : large transparency in the infrared range, a high refractive index (n>2) and strong non-linear properties. The realization of microstructured optical fibers (MOFs) exacerbates non-linear effects more particularly by varying the opto-geometrical parameters of the fibers (d and Λ). Thus, single-mode propagation can be obtained and also generation of non-linear effects. The realization of high purity chalcogenide glasses is needed. In fact, absorption bands limiting the transparency of the fibers must be identified and minimized. For this, monitoring and qualification of components used in the synthesis of glasses should be undertaken. A protocol of synthesis and purification by heat treatment was implemented in this direction. The technique to elaborate MOFs is the casting method. It consists of flowing a glass on a silica mold. The geometry is the negative shape of the desired fiber. This method allows the realization of multimode or single-mode fiber in the 1-10 μm window. The realization of infrared sources was developed in the manuscript. The generation of a supercontinuum with a suspended-core fiber has been presented and also by the realization of a quantum cascade laser (QCL) coupled into a singlemode fiber. In addition, a polarization-maintaining fiber (PMF) having a group birefringence of the order of 10-3 was developed through the evolution of the silica mold. In addition, an optical coupler, an all-solid fiber and an infrared bundle were achieved during this thesis

APA, Harvard, Vancouver, ISO, and other styles

3

Issa, Nader. "Modes and propagation in microstructured optical fibres." University of Sydney. Physics and Optical Fibre Technology Centre, 2005. http://hdl.handle.net/2123/613.

Full text

Abstract:

Microstructured optical fibres (MOFs), also commonly called photonic crystal fibres or holey fibres, describe a type of optical fibre in which continuous channels of (typically) air run their entire length. These `holes' serve to both confine electromagnetic waves within the core of the fibre and to tailor its transmission properties. In order to understand and quantify both of these functions, a new computational algorithm was developed and implemented. It solves for the eigenvalues of Maxwell's wave equations in the two-dimensional waveguide cross-section, with radiating boundary conditions imposed outside the microstructure. This yields the leaky modes supported by the fibre. The boundary conditions are achieved exactly using a novel refinement scheme called the Adjustable Boundary Condition (ABC) method. Two implementations are programmed and their computational efficiencies are compared. Both use an azimuthal Fourier decomposition, but radially, a finite difference scheme is shown to be more efficient than a basis function expansion. The properties of the ABC method are then predicted theoretically using an original approach. It shows that the method is highly efficient, robust, automated and generally applicable to any implementation or to other radiating problems. A theoretical framework for the properties of modes in MOFs is also presented. It includes the use of the Bloch-Floquet theorem to provide a simpler and more efficient way to exploit microstructure symmetry. A new, but brief study of the modal birefringence properties in straight and spun fibres is also included. The theoretical and numerical tools are then applied to the study of polymer MOFs. Three types of fibres are numerically studied, fabricated and characterised. Each is of contemporary interest. Firstly, fabrication of the first MOFs with uniformly oriented elliptical holes is presented. A high degree of hole ellipticity is achieved using a simple technique relying on hole deformation during fibre draw. Both form and stress-optic birefringence are characterized over a broad scaled-wavelength range, which shows excellent agreement with numerical modelling. Secondly, an analysis of leaky modes in real air core MOFs, fabricated specifically for photonic band gap guidance, is then used to identify alternative guiding mechanisms. The supported leaky modes exhibit properties closely matching a simple hollow waveguide, weakly influenced by the surrounding microstructure. The analysis gives a quantitative determination of the wavelength dependent confinement loss of these modes and illustrates a mechanism not photonic band gap in origin by which colouration can be observed in such fibres. Finally, highly multimode MOFs (also called `air-clad' fibres) that have much wider light acceptance angles than conventional fibres are studied. An original and accurate method is presented for determining the numerical aperture of such fibres using leaky modes. The dependence on length, wavelength and various microstructure dimensions are evaluated for the first time for a class of fibres. These results show excellent agreement with published measurements on similar fibres and verify that bridge thicknesses much smaller than the wavelength are required for exceptionally high numerical apertures. The influence of multiple layers of holes on the numerical aperture and capture efficiency are then presented. It shows that a substantial increase in both these parameters can be achieved for some bridge thicknesses. Simple heuristic expressions for these quantities are given, which are based on the physical insight provided by the full numerical models. The work is then supported by the first fabrication attempts of large-core polymer MOFs with thin supporting bridges. These fibres exhibit relatively high numerical apertures and show good agreement with theoretical expectations over a very wide scaled-wavelength range.

APA, Harvard, Vancouver, ISO, and other styles

4

Lyytik�inen, Katja Johanna. "Control of complex structural geometry in optical fibre drawing." University of Sydney. School of Physics and the Optical Fibre Technology Centre, 2004. http://hdl.handle.net/2123/597.

Full text

Abstract:

Drawing of standard telecommunication-type optical fibres has been optimised in terms of optical and physical properties. Specialty fibres, however, typically have more complex dopant profiles. Designs with high dopant concentrations and multidoping are common, making control of the fabrication process particularly important. In photonic crystal fibres (PCF) the inclusion of air-structures imposes a new challenge for the drawing process. The aim of this study is to gain profound insight into the behaviour of complex optical fibre structures during the final fabrication step, fibre drawing. Two types of optical fibre, namely conventional silica fibres and PCFs, were studied. Germanium and fluorine diffusion during drawing was studied experimentally and a numerical analysis was performed of the effects of drawing parameters on diffusion. An experimental study of geometry control of PCFs during drawing was conducted with emphasis given to the control of hole size. The effects of the various drawing parameters and their suitability for controlling the air-structure was studied. The effect of air-structures on heat transfer in PCFs was studied using computational fluid dynamics techniques. Both germanium and fluorine were found to diffuse at high temperature and low draw speed. A diffusion coefficent for germanium was determined and simulations showed that most diffusion occurred in the neck-down region. Draw temperature and preform feed rate had a comparable effect on diffusion. The hole size in PCFs was shown to depend on the draw temperature, preform feed rate and the preform internal pressure. Pressure was shown to be the most promising parameter for on-line control of the hole size. Heat transfer simulations showed that the air-structure had a significant effect on the temperature profile of the structure. It was also shown that the preform heating time was either increased or reduced compared to a solid structure and depended on the air-fraction.

APA, Harvard, Vancouver, ISO, and other styles

5

Lyytikäinen, Katja Johanna. "Control of complex structural geometry in optical fibre drawing." Thesis, The University of Sydney, 2004. http://hdl.handle.net/2123/597.

Full text

Abstract:

Drawing of standard telecommunication-type optical fibres has been optimised in terms of optical and physical properties. Specialty fibres, however, typically have more complex dopant profiles. Designs with high dopant concentrations and multidoping are common, making control of the fabrication process particularly important. In photonic crystal fibres (PCF) the inclusion of air-structures imposes a new challenge for the drawing process. The aim of this study is to gain profound insight into the behaviour of complex optical fibre structures during the final fabrication step, fibre drawing. Two types of optical fibre, namely conventional silica fibres and PCFs, were studied. Germanium and fluorine diffusion during drawing was studied experimentally and a numerical analysis was performed of the effects of drawing parameters on diffusion. An experimental study of geometry control of PCFs during drawing was conducted with emphasis given to the control of hole size. The effects of the various drawing parameters and their suitability for controlling the air-structure was studied. The effect of air-structures on heat transfer in PCFs was studied using computational fluid dynamics techniques. Both germanium and fluorine were found to diffuse at high temperature and low draw speed. A diffusion coefficent for germanium was determined and simulations showed that most diffusion occurred in the neck-down region. Draw temperature and preform feed rate had a comparable effect on diffusion. The hole size in PCFs was shown to depend on the draw temperature, preform feed rate and the preform internal pressure. Pressure was shown to be the most promising parameter for on-line control of the hole size. Heat transfer simulations showed that the air-structure had a significant effect on the temperature profile of the structure. It was also shown that the preform heating time was either increased or reduced compared to a solid structure and depended on the air-fraction.

APA, Harvard, Vancouver, ISO, and other styles

6

Balme, Coraline. "Génération de sources optiques fibrées très hautes cadences et caractérisation de fibres optiques microstructurées en verre de Chalcogénure." Thesis, Dijon, 2011. http://www.theses.fr/2011DIJOS022/document.

Full text

Abstract:

Ce mémoire de thèse s'inscrit dans le contexte du projet FUTUR financé par l'ANR et concernant le développement de Fonctions optiques pour les Transmissions à très haut débit dans le Réseau coeur et porte sur la génération de sources optiques fibrées très hautes cadences et la caractérisation de fibres optiques microstructurées en verre de Chalcogénure. A cet effet, nous étudions les caractéristiques linéaires et non-linéaires au sein de fibres microstructurées en verre de chalcogénures conçue et réaliser via différentes collaborations dans le cadre du projet de l'ANR FUTUR. Pour cela un grand nombre de méthodes de caractérisations ont été mises au point donnant une comparaison entre une fibre SMF standard et ces fibres microstructurées chalcogénures. Par exemple, un montage interférométrique pour la mesure de la dispersion chromatique pour échantillon court, ou encore de nombreux banc expérimentaux permettant la caractérisation des propriétés non-linéaires de ces fibres (diffusion Raman, diffusion Brillouin, Coefficient non linéaire Kerr...). La seconde partie de ce mémoire présente la mise au point de méthode de conversion d'un battement sinusoïdal en un train d'impulsions hautement cadencé. Il est montré dans ce manuscrit que cette technique a été exploitée au plus prêt de ses limites, par l'obtention d'impulsions extrêmement courtes et par des débits très élevés. Les trains d'impulsions à très hautes cadences ont été caractérisés par un dispositif expérimental SHG-FROG. Une démonstration de la multiplication du débit par deux a été démontrée par l'effet Talbot
This memory of thesis s' registered voter in the context of the FUTUR project financed by l'ANR and concerning the development of optical finctions fot the high bit-rate transmissions in the Network heart and carries on very high rates optical fibers sources generation and the optical chalcogenide microstructured fiber charaterization. For this purpose, we study the linear and non-linear characteristics of microstructured chalcogenide fibers conceived and realized in various collaborations within the framework of the ANR FUTUR project. For that a great number of characterizations methods were developed giving a comparison between a standard single mode fiber and there microstructured chalcogenide fibers. For exemple, an interferometric setup for the chromatic dispersion measurement for short sample, or many experimental setup allowing the nonlinear properties characterizations as of these fibers (Raman scattering, nonlinear Kerr Coefficient). The second part of this memory presents the settling of sinusoidal beat conversion into a high bit rate generation method. It is shown in this manuscript that this technique was exploited with readiest of its limits, by obtaining extremely short pulses and by very high bit-rate. The pulses train at very high rates were characterized by an experimental device SHG-FROG. A demonstration of the multiplication of the bit-rate by two at summer shown by Talbot effect

APA, Harvard, Vancouver, ISO, and other styles

7

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

8

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Li, Qingquan. "Microstructured optical fibres in chalcogenide glass." Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602615.

Full text

Abstract:

Chalcogenide glasses offer transmission windows within the far-visible, near- and midinfrared (IR) range. They exhibit potentially excellent linear and large non linear optical properties, photosensitivity and their low phonon energies are conducive to efficient dopant rare earth transitions. These properties enable many potential infrared applications: large-scale optics; fibreoptics; integrated optics; optical imaging; optical data storage and all-optical switching. Two lines of experimental work were followed in this project based on chalcogenide glasses, as below: (1) Antimony was used to replace arsenic, to fOIm the ternary Ge-Sb-Se glass system. Nine compositions of Ge-Sb-Se glasses were synthesised and characterised to reveal their glass forming abilities, thermal properties and optical properties. Glass pairs, with close thermal propeIties and relatively high refractive index contrast, were developed for fabricating core-clad. structure step index fibre and micro structured optical fibres (MOFs). (2) Fabrication of an all-solid chalcogenide glass micro structured fibre (MOF), which was designed as a mimic of the holey suspended structure silica MOF, was canied out. A cane-drawing technique and a real-time contactless diameter monitor of the chalcogenide canes were developed to improve the precision of the fabrication. Stacking equipment was designed to improve the technique of the chalcogenide preform stacking.

APA, Harvard, Vancouver, ISO, and other styles

10

Issa, Nader A. "Modes and propagation in microstructured optical fibres." Connect to full text, 2005. http://hdl.handle.net/2123/613.

Full text

Abstract:

Thesis (Ph. D.)--University of Sydney, 2005.
Title from title screen (viewed 21 May 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Optical Fibre Technology Centre, School of Physics. Includes bibliographical references. Also available in print form.

APA, Harvard, Vancouver, ISO, and other styles

11

Voyce, Christopher Jonathan. "The mathematical modelling of microstructured optical fibres." Thesis, University of Southampton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433931.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Furusawa, Kentaro. "Development of rare-earth doped microstructured optical fibres." Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/15481/.

Full text

Abstract:

This thesis describes the development of novel optical fibres, microstructured optical fibres (MOFs), and demonstrates device applications based on these structures. A particular emphasis is made on incorporating rare-earth ions within these fibres in order to realise novel active devices. Together with the development of the fabrication technique, characterisation and applications of these radically different fibre types are presented. First, the fabrication techniques of MOFs, which heavily rely upon fibre drawing, are studied. A mathematical model developed for the capillary drawing process is experimentally examined. Good agreement is obtained whilst it is also found that the model provides useful physical insights for determining the fibre draw parameters even for MOFs with complex geometries. Details of the fabrication techniques developed to optimise fibre structures are also presented. Transmission properties of highly nonlinear MOFs are then studied experimentally. It is found that the transmission losses are strongly influenced by the core dimensions due to the high Rayleigh scattering coefficient that originates from the holey cladding. A simple model is used to explain the observations. In addition, a continuous effort towards reducing OH-induced losses of this fibres type is outlined. Rare-earth doped highly nonlinear MOFs are fabricated and characterised. Then, three device demonstrations are carried out for the first time. These include a mode-locked ytterbium doped MOF laser, a nonlinear amplifier based on an ytterbium doped MOF, and a continuous wave erbium doped MOF laser with a very low threshold and high efficiency. Using the ytterbium doped MOF, wide tunability of ultrashort pulses from 1µm to 1.58µm is demonstrated using the soliton self frequency shift effect. For the erbium doped MOF, a pump power threshold of 0.5mW and a slope efficiency of 57% are demonstrated. Novel cladding pumped fibres, air clad MOFs, which use a conventional inner cladding and a holey outer cladding, are developed aiming at improved performance of cladding pumped fibre lasers. Wide tunability over 110nm and pure three level operation at 980nm of ytterbium doped cladding pumped fibre lasers are demonstrated. Finally, the fabrication and characterisation of large mode area microstructured fibres (LMA-MOFs) are described, and a comparison with conventional counterparts is made in terms of bend losses and corresponding effective mode areas. The results show that a slight refractive index difference introduced in the core region of this fibre type strongly modifies its waveguide characteristics. By applying this knowledge, a novel ytterbium doped cladding pumped fibre, which uses different sizes of air holes to define the inner and outer cladding, is developed. A continuous wave output power in excess of 1W is obtained. Results concerning various forms of pulsed laser operation using this fibre are presented and future possibilities are discussed.

APA, Harvard, Vancouver, ISO, and other styles

13

Poletti, Francesco. "Direct and inverse design of microstructured optical fibres." Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/47759/.

Full text

Abstract:

Microstructured optical fibres, where an arrangement of air holes running longitudinally along the fibre guides light in either a solid or a hollow core, have created new opportunities in diverse areas of science and technology. Applications range from the generation of supercontinuum light to optical sensing, nonlinear telecom devices and the generation and delivery of extremely high optical powers. Photonic bandgap fibres, allowing light guidance in a hollow core, are also extensively studied. The main issues preventing accurate simulations of the properties of fabricated fibres are identified and addressed. An ideal, accurate representation of a realistic fibre is then proposed and employed to obtain fundamental scaling rules and to study the interactions between air guided and surface guided modes. Anticrossings between these modes in slightly asymmetric structures are identified as the cause for the unusual polarisation effects experimentally observed in these fibres. And finally, guidelines for fabricating fibres with the widest possible operational bandwidth possible are developed and presented.

APA, Harvard, Vancouver, ISO, and other styles

14

Picot-Clémente, Jérémy. "Etude de sources supercontinuum à fibres optiques en verre de tellurite pour la spectroscopie d'absorption moyen infrarouge appliquées à la détection de gaz." Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS040/document.

Full text

Abstract:

Ce manuscrit de thèse présente le développement et l’étude d’une source supercontinuum dans l’infrarouge moyen pour une application de détection de gaz par spectroscopie d’absorption. L’étude des sources supercontinuum est basée sur la propagation non-linéaire d’impulsions ultracourtes dans un verre de tellurite de composition 80TeO2-10ZnO-10Na2O (% molaire) et utilisé sous trois formes différentes, à savoir un échantillon massif sous la forme d’une pastille, puis une fibre microstructurée à cœur suspendu fabriquée à partir de ce même verre, et enfin cette dernière fibre ultérieurement effilée (aussi appelée « taper »). Ces trois options d’utilisation s’adaptent à différents types de sources lasers disponibles commercialement et permettent d’optimiser la génération d’une source de lumière recouvrant une gamme très large de fréquences. Chaque observation expérimentale est accompagnée de simulations numériques correspondantes qui mettent en évidence les différents mécanismes physiques et dynamiques de la génération de supercontinuum. La première étude reporte la mise en œuvre d’une source supercontinuum induite par filamentation dans l’échantillon massif, à l’aide d’un laser femtoseconde de forte énergie (plusieurs micro-Joules), et associée à une caractérisation spectro-angulaire complète. Puis, l’accent a été mis sur la génération de supercontinuum dans les fibres optiques microstructurées à cœur suspendu (avec ou sans taper) à l’aide de sources lasers femtosecondes nano-Joules. Une étude complète de fabrication et d’optimisation des propriétés de ces fibres avec ou sans taper a été menée, notamment pour améliorer les contributions linéaires et non-linéaires du guidage sur la propagation et les conversions de fréquences associées. Une source supercontinuum s’étalant de 0.6 à 3.3 µm (équivalent à 400 THz de largeur spectrale) est obtenue avec une fibre d’une longueur de 10 cm. Enfin, une source s’étalant de 0.9 à 2.6 µm, à l’aide d’un laser à fibre plus compact, a été développée grâce aux fibres microstructurées effilées pour une application de détection de gaz. Le principal objectif étant d’explorer les raies d’absorption au-delà de 2 µm, qui sont reconnues comme étant bien plus intenses et donc plus faciles à détecter. Un dispositif expérimental de spectroscopie d’absorption par source supercontinuum dans une cellule multi-passage compacte a été mis en place avec succès pour la détection de méthane
This work focuses on the development of mid-infrared supercontinuum light sources and their application for gas detection through absorption spectroscopy. The study of supercontinuum sources is based on nonlinear ultrashort pulse propagation in tellurite glass (80TeO2-10ZnO-10Na2O) and used in three different forms, namely a thin bulk sample, a microstructured suspended-core fiber, and a tapered suspended-core fiber. These technical means adapt themselves to distinct laser sources commercially available, thus optimizing the implementation of ultrawide-band infrared light sources. Experimental observations are compared to corresponding numerical simulations, thus pointing out the different underlying physical mechanisms of supercontinuum generation. The first study reports the filamentation-induced supercontinuum source in the tellurite glass bulk sample by means of a high-energy femtosecond laser (several micro-Joules) and associated with a complete spectro-angular mapping of light distribution. Then, the main task is related to supercontinuum generation in microstructured suspended-core fibers (with or without tapering) using nano-Joule femtosecond laser sources. A complete analysis of the fiber design was performed, especially to enhance linear and nonlinear wave propagation for efficient frequency conversion processes. As a result, a supercontinuum source covering the 0.6-3.3 µm region (i.e., 400-THz spectral bandwidth) is obtained in a 10-cm tapered fiber segment. Finally, another supercontinuum source covering the 0.9-2.6 µm region, pumped by a very compact fiber laser, was developed, in particular for its application in a gas detector system. The main goal is to explore absorption lines beyond 2 µm, which are known to be more intense and then easier to detect. A complete experimental setup for supercontinuum absorption spectroscopy based on a compact multi-pass cell was successfully developed for methane detection

APA, Harvard, Vancouver, ISO, and other styles

15

Tchahame, Nougnihi Joel Cabrel. "Diffusion Brillouin dans des fibres optiques étirées et microstructurées." Thesis, Besançon, 2016. http://www.theses.fr/2016BESA2049/document.

Full text

Abstract:

Cette thèse de doctorat porte sur une étude fondamentale de la diffusion Brillouin dans desmicrofibres optiques et des fibres optiques microtructurées à petit cœur. Par le biais d’expérienceset de simulations numériques, nous avons ainsi démontré que le gain Brillouin dans des microfibresoptiques à base de verre chalcogénure peut atteindre une valeur 150 à250 fois supérieure à celled’une fibre optique conventionnelle. Par ailleurs, nous avons également reporté la génération desspectres Brillouin multi-pics dans une fibre optique microstucturée à petit cœur, dont les paramètresopto-géométriques varient le long de la fibre. L’étude de ces spectres particuliers montre que lecomportement multi-résonant provient à la fois de l’excitation d’ondes acoustiques hybrides, etde la g´eom´ etrie de la fibre optique. Un autre travail marquant de cette thèse est la mise enévidence des ondes acoustiques de surface dans une configuration guidée. Pour la première fois`a notre connaissance, nous avons observé et caractérisé la diffusion Brillouin de surface dans desfibres optiques microstructurées à petit cœur, et `a fort taux de remplissage d’air. Nos résultatsmontrent notamment que ce nouveau mode de diffusion est extrêmement sensible à la géométriedes fibres optiques microstructurées. L’ensemble de ces travaux de thèse apportent une meilleurecompréhension de la diffusion Brillouin dans des fibres optiques à section sub-longueur d’onde,ouvrant ainsi la voie vers la réalisation de nouveaux composants fibrés opto-acoustiques, pour lestélécommunications et les capteurs
This PhD thesis focuses on the fundamental aspects of Brillouin scattering in chalcogenidemicrofibers and silica photonic crystal fibers with wavelength-scale solid core. Through experimentalinvestigations and numerical simulations, we have demonstrated that the Brillouin gain inchalcogenide microfiber can reach a value 150 to 250 times higher than in conventional opticalfibers. Moreover, we have reported the generation of multipeaked Brillouin spectra in a long taperedbirefringent photonic crystal fiber. A further investigation of these spectra shows that the multiresonantbehavior arises both from the excitation of hybrid acoustic waves and the fiber tapering.Another significant work of this thesis is the evidence of surface acoustic waves in small-core photoniccrystal fibers with large air filling fraction. Our results show specifically that this new type of scatteringis extremely sensitive to the air-hole microstructure geometry. Finally, these works contribute toa better understanding of Brillouin scattering in ultrathin optical fiber, paving the way towards therealization of new optoacoustic components for telecommunications and sensors

APA, Harvard, Vancouver, ISO, and other styles

16

Kominsky, Daniel. "Development of Random Hole Optical Fiber and Crucible Technique Optical Fibers." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/28949.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

17

Waalib-Singh, Nirmal. "Metastable entangled ordered structures in predeformed and preconditioned polymer optical fibres." Thesis, The University of Sydney, 2008. https://hdl.handle.net/2123/28122.

Full text

Abstract:

The nature of fibre optics transmission has been the subject of various studies since the first optical fibres were discovered and manufactured in the early 1960's. However, to date, few have investigated, let alone correlated results from the mechanical and thermal testing of these fibres with respect to those optical properties that are usually reported.

APA, Harvard, Vancouver, ISO, and other styles

18

Amezcua-Correa, Adrian. "Deposition of electronic and plasmonic materials inside microstructured optical fibres." Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/50201/.

Full text

Abstract:

Optical fibres are the transport medium of today's digital information. Nowadays, modern optical telecommunication systems make use of semiconductor optoelectronic devices to generate, control and detect light. The union of the two technologies, namely fibre photonics and semiconductor electronics is expected to have a major impact on next generation of optoelectronic devices, exploiting both the guiding capabilities of optical fibres and the signal processing properties of semiconductors devices. Only recently, with the advent of microstructured optical fibres and templating material processing methods, it has been possible to create optical fibres with solid-state material inclusions. An experimental investigation on the optical transmission properties of microstructured optical fibres impregnated with silver nanoparticles is also presented. These fibres are shown to be an excellent way of coupling optical guided modes into surface plasmons. As a result, they represent a promising platform technology for fully integrated photonic/plasmonic devices. These fibres have demonstrated the enhancement of Raman signals from molecules adsorbed onto the inner metal surfaces and thus ideally suited for Surface Enhance Raman Scattering molecular detection.

APA, Harvard, Vancouver, ISO, and other styles

19

Kuhlmey, Boris T. "Theoretical and Numerical Investigation of the Physics of Microstructured Optical Fibres." Thesis, The University of Sydney, 2003. http://hdl.handle.net/2123/560.

Full text

Abstract:

We describe the theory and implementation of a multipole method for calculating the modes of microstructured optical fibers (MOFs). We develop tools for exploiting results obtained through the multipole method, including a discrete Bloch transform. Using the multipole method, we study in detail the physical nature of solid core MOF modes, and establish a distinction between localized defect modes and extended modes. Defect modes, including the fundamental mode, can undergo a localization transition we identify with the mode's cutoff. We study numerically and theoretically the cutoff of the fundamental and the second mode extensively, and establish a cutoff diagram enabling us to predict with accuracy MOF properties, even for exotic MOF geometries. We study MOF dispersion and loss properties and develop unconventional MOF designs with low losses and ultra-flattened near-zero dispersion on a wide wavelength range. Using the cutoff-diagram we explain properties of these MOF designs.

APA, Harvard, Vancouver, ISO, and other styles

20

Kuhlmey, Boris T. "Theoretical and Numerical Investigation of the Physics of Microstructured Optical Fibres." University of Sydney and Universite Aix-Marseille III. School of Physics, 2003. http://hdl.handle.net/2123/560.

Full text

Abstract:

We describe the theory and implementation of a multipole method for calculating the modes of microstructured optical fibers (MOFs). We develop tools for exploiting results obtained through the multipole method, including a discrete Bloch transform. Using the multipole method, we study in detail the physical nature of solid core MOF modes, and establish a distinction between localized defect modes and extended modes. Defect modes, including the fundamental mode, can undergo a localization transition we identify with the mode�s cutoff. We study numerically and theoretically the cutoff of the fundamental and the second mode extensively, and establish a cutoff diagram enabling us to predict with accuracy MOF properties, even for exotic MOF geometries. We study MOF dispersion and loss properties and develop unconventional MOF designs with low losses and ultra-flattened near-zero dispersion on a wide wavelength range. Using the cutoff-diagram we explain properties of these MOF designs.

APA, Harvard, Vancouver, ISO, and other styles

21

Hage, Charles-Henri. "Sources optiques fibrées pour applications biomédicales." Phd thesis, Université de Bourgogne, 2013. http://tel.archives-ouvertes.fr/tel-00907642.

Full text

Abstract:

Ce mémoire présente les travaux effectués sur le développement d'une source optique servant à des applications d'imagerie biomédicale en général et de diffusion Raman cohérente en particulier. En effet la diffusion de ces dernières est freinée par le verrou technologique que constitue la nécessité de deux impulsions synchronisées et décalées en longueur d'onde. La praticité et les possibilités de conversions de fréquences offertes par l'optique non-linéaire fibrée sont ainsi utilisées pour adresser ce verrou technologique. Tout d'abord, une source simplement réglable en longueur d'onde est générée par l'effet d'auto-décalage en fréquence optique d'un soliton par effet Raman. Une étude des principaux paramètres de fibre aboutit à des décalages de 320 à plus de 500 nm, permettant une imagerie des résonances d'intérêt (≈ 1000-4000 cm-1). Deux applications de ce décalage sont présentées. Ensuite, l'autre impulsion voit sa largeur spectrale réduite de 70 à 10 cm-1 par compression spectrale, qui consiste en un "regroupement non-linéaire de fréquences sans pertes", afin de bénéficier de la résolution spectrale nécessaire. Enfin, la source développée est validée par l'acquisition de spectres CARS de différents échantillons de référence, pour différentes résonances (850 à 1750 cm-1). Une extension de la source à d'autres types d'imagerie est proposée, ainsi qu'une architecture de source quasiment entièrement fibrée exploitant les principes développés au cours de cette thèse

APA, Harvard, Vancouver, ISO, and other styles

22

Fraser, Michael John. "Optical Fiber Microstructures for Self-Contained Whispering Gallery Mode Excitation." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/73659.

Full text

Abstract:

Optical resonators, which confine light by resonant recirculation, serve as the basis for a wide variety of optical components. Though they appear in many geometric forms, the most effective of optical resonators show axial symmetry in at least one dimension. A popular variation that finds broad application is the dielectric sphere. Acclaimed for their high quality (Q) factor and small modal volume, spheres owe credit of these attractive features to their support of whispering gallery mode (WGM) resonances. The sensitivity of a resonance's frequency and Q to strain, temperature, and other parameters of the surrounding medium can be the basis for ultracompact modulators and sensors. Physically, WGMs are special optical modes which can be understood as light rays that orbit the equator of the sphere guided by total internal reflection. Like a smooth stone can be skipped along the surface of a pond, light can be confined to the inside of a sphere by successive reflections. To best excite WGMs, the source light should initially trace a line tangent to the sphere's circumference. But incorporating a tiny sphere with such nanometric tolerances into a practical sensor structure has its challenges and the prospects for microsphere applications have suffered because of the plight of this problem. The work in this dissertation details the fabrication and function of three new "press fit" spherical resonators. These etched fiber micro-devices were developed to meet the demand for a robust, self-integrated means of coupling light between an optical fiber and WGMs in a microsphere resonator. The etching processes have been tuned to enable secure storage of a microsphere while also providing efficient excitation and interrogation of WGMs. Furthermore, the methods have been designed to be staightforward, quick, and repeatable. Using standard etchants on common polarization-maintaining fiber with readily purchased microspheres, the press fit resonators demonstrated here can be batch-fabricated and assembled. The press fit spherical resonator offers an alignment-free and conveniently pigtailed WGM coupler that has great potential for bio-science sensing applications and studies of resonant bispheres.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

23

Zhang, Yun Hua. "Analysis and design of microstructured fibres for optical and terahertz applications." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539676.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Kuhlmey, Boris. "Theoretical and numerical investigation of the physics of microstructured optical fibres." Aix-Marseille 3, 2003. http://www.theses.fr/2003AIX30024.

Full text

Abstract:

Nous détaillons la théorie et l'implémentation d'une méthode multipolaire pour le calcul de modes de fibres optiques microstructurées (FOM). Nous développons des outils pour l'exploitation de résultats obtenus par la méthode multipolaire, dont une transformée de Bloch discrète. Nous étudions la nature physique de modes de FOMs à cœur plein et distinguons entre modes de défaut localisés et modes étendus. Les modes de défaut subissent une transition de localisation que nous identifions à la coupure du mode. Nous étudions numériquement et théoriquement la coupure du mode fondamental et du second mode, puis établissons un diagramme de régime opératoire. Celui-ci permet de prédire les propriétés de FOMs même aux géométries complexes. En nous aidant du diagramme de régime opératoire, nous étudions la dispersion et les pertes des FOMs et proposons un nouveau type de FOM à faibles pertes et à courbe de dispersion ultra plate, proche de zéro sur une vaste plage de longueur d'ondes
We describe the theory and implementation of a multipole method for calculating the modes of microstructured optical fibers (MOFs). We develop tools for exploiting results obtained through the multipole method, including a discrete Bloch transform. Using the multipole method, we study in detail the physical nature of solid core MOF modes, and establish a distinction between localized defect modes and extended modes. Defect modes, including the fundamental mode, can undergo a localization transition we identify with the mode's cutoff. We study numerically and theoretically the cutoff of the fundamental and the second mode extensively, and establish a cutoff diagram enabling us to predict with accuracy MOF properties, even for exotic MOF geometries. We study MOF dispersion and loss properties and develop unconventional MOF designs with low losses and ultra-flattened near-zero dispersion on a wide wavelength range. Using the cutoff-diagram we explain properties of these MOF designs

APA, Harvard, Vancouver, ISO, and other styles

25

Santos, Alexandre Bozolan dos. "Dispositivos baseados no preenchimento de fibras de cristal fotônico por líquidos e materiais nanoestruturados." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18155/tde-06062012-112247/.

Full text

Abstract:

Esta tese descreve a demonstração experimental de dispositivos baseados em fibras de cristal fotônico (PCFs), que aproveitam a flexibilidade estrutural oferecida pela matriz de capilares que compõe a seção reta da fibra, de forma a preencher estes capilares com líquidos e materiais nanoestruturados. Para o caso de materiais nanoestruturados, uma vez preenchida a fibra, os materiais nela inseridos interagem eficientemente com a luz guiada. Essa arquitetura diferenciada em relação às fibras ópticas convencionais abre novas perspectivas no desenvolvimento de aplicações como óptica não-linear e sensoriamento. PCFs de núcleo líquido, por outro lado, impõe dificuldades para a implementação de dispositivos práticos, devido às altas taxas de evaporação dos líquidos inseridos. Por esta razão, foi desenvolvida uma nova técnica para vedar seletivamente ambas as faces externas do núcleo líquido de uma PCF, utilizando um polímero curável. Estes tampões poliméricos evitam a evaporação, causando um impacto mínimo no guiamento da luz, tornando o dispositivo usável por semanas. Esta nova técnica de vedação foi empregada em um experimento para a geração de supercontínuo em uma PCF com núcleo de água destilada, proporcionando uma estabilidade de pelo menos 1 hora. Combinando líquidos e materiais nanoestruturados, foi também foi desenvolvido um sensor de temperatura baseado no preenchimento do núcleo de uma PCF por uma amostra coloidal de nanopartículas semicondutoras de CdSe/ZnS, dispersas em óleo mineral. O espectro de luminescência destes pontos quânticos coloidais é fortemente dependente da temperatura e os resultados obtidos mostraram que a grande interação entre a luz e o colóide, aliada a geometria da fibra, proporcionando uma sensibilidade ~5,5 vezes maior que a apresentada por uma rede de Bragg escrita em uma fibra óptica padrão, com boa relação sinal-ruído.
This thesis describes the experimental demonstration of devices based on photonic crystal fibers (PCFs). PCFs are optical fibers whose core is surrounded by a regular matrix of holes, which runs longitudinally across its length. This singular configuration allows the insertion of liquids and nanostructured material into the fiber. Nanostructured materials embedded inside the fiber efficiently interact with the guided light, opening up possibilities of novel applications regarding the fields of non-linear optics, as well as optical sensing. On the other hand, liquid-core PCFs suffer from some disadvantages concerning practical device applications, on account of the high evaporation of the inserted liquids. In order to address this issue, we developed a novel technique to selectively seal the external faces of a liquid-core PCF, by using a polymer plug. These polymer plugs avoid evaporation while causing a minimum impact on the light guiding characteristics of the PCF. This novel sealing technique was employed in a supercontinuum generation experiment, by using a PCF whose core was water-filled. A temporal stability of at least one-hour on the resulting spectrum was achieved. Combining the above techniques, we also developed a temperature sensor based on the core-filling of a PCF by a colloidal ensemble of CdSe/ZnS semiconductor nanoparticles dispersed in mineral oil. Those colloidal quantum-dots display a luminescence spectrum which is strongly dependent on temperature and the experimental results indicated that the greater interaction between the guided light and the colloidal sample, provided by the fiber geometry, allowed a sensitivity which is approximately 5.5 times than possible with a conventional Bragg grating, while keeping a satisfactory signal-to-noise ratio.

APA, Harvard, Vancouver, ISO, and other styles

26

Kim, Jeong I. "Analysis and Applications of Microstructure and Holey Optical Fibers." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/29089.

Full text

Abstract:

Microstructure and photonic crystal fibers with periodic as well as random refractive-index distributions are investigated. Two cases corresponding to fibers with one-dimensional (1D) radial index distributions and two-dimensional (2D) transverse index distributions are considered. For 1D geometries with an arbitrary number of cladding layers, exact analytical solutions of guided modes are obtained using a matrix approach. In this part, for random index distributions, the average transmission properties are calculated and the influence of glass/air ratio on these properties is assessed. Important transmission properties of the fundamental mode, including normalized propagation constant, chromatic dispersion, field distributions, and effective area, are evaluated. For 2D geometries, the numerical techniques, FDTD (Finite-Difference Time-Domain) method and FDM (Finite Difference Method), are utilized. First, structures with periodic index distributions are examined. The investigation is then extended to microstructure optical fibers with random index distributions. Design of 2D microstructure fibers with random air-hole distributions is undertaken with the aim of achieving single-mode guiding property and small effective area. The former is a unique feature of the holey fiber with periodic air-hole arrangement and the latter is a suitable property for nonlinear fiber devices. Measurements of holey fibers with random air-hole distributions constitute an important experimental task of this research. Using a section of a holey fiber fabricated in the draw tower facility at Virginia Tech, measurements of transmission spectra and fiber attenuation are performed. Also, test results for far-field pattern measurements are presented. Another objective of this dissertation is to explore new applications for holey fibers with random or periodic hole distributions. In the course of measuring the holey fibers, it was noticed that robust temperature-insensitive pressure sensors can be made with these fibers. This offers an opportunity for new low-cost and reliable pressure fiber-optic sensors. Incorporating gratings into holey fibers in conjunction with the possibility of dynamic tuning offers desirable characteristics with potential applications in communications and sensing. Injecting gases or liquids in holey fibers with gratings changes their transmission characteristics. These changes may be exploited in designing tunable optical filters for communication applications or making gas/liquid sensor devices.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

27

Spadoti, Danilo Henrique. "Proposição e estudo de fibras ópticas microestruturadas tipo D: gerenciamento de dispersão e alta birrefringência." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/18/18155/tde-15122008-105637/.

Full text

Abstract:

Este trabalho de doutoramento propôs investigar novas configurações geométricas para as fibras ópticas microestruturadas a base de sílica. Aproveitando-se da flexibilidade que sua geometria proporciona, diferentes das fibras ópticas convencionais, foram propostas fibras ópticas microestruturadas com perfil tipo D atuando, especificamente, em duas aplicações distintas: fibras compensadoras de dispersão ou fibras altamente birrefringentes. Para o estudo teórico das fibras ópticas microestruturadas foram utilizados dois métodos numéricos: o método da Sobre-Relaxação Sucessiva (SOR) e o método de Arnoldi Implicitamente Reiniciado (IRAM). Foi necessário implementar o método IRAM para determinar os modos de mais alta ordem presentes em guias de onda multimodos, uma vez que o método SOR fornece apenas a solução para o modo fundamental. Neste contexto, as fibras ópticas microestruturadas com perfil D, propostas e investigadas neste trabalho, demonstraram ser extremamente promissoras para atuar na compensação da dispersão cromática ou no aumento do efeito da birrefringência. Foram projetadas fibras capazes de compensar a dispersão em banda larga, cobrindo as bandas de telecomunicações S, C e L, ou, ainda, fibras com um alto coeficiente de dispersão negativo em torno do comprimento de onda de 1550nm. Adicionalmente, verificou-se também que com as novas configurações propostas foi possível projetar fibras com elevado grau de birrefringência, sendo atrativas no projeto de fibras mantedoras do estado de polarização.
This work proposed to investigate new geometric configurations for the silica microstructured optical fibers. Based on their design flexibility, not usually found in conventional silica fibers, D-shape microstructured optical fibers were designed, specifically, for two different applications: dispersion compensation or high birefringence. For the theoretical analysis two numerical methods were used: the finite difference Successive Over Relaxation (SOR) method, and the Implicitly Restarted Arnoldi Method (IRAM). It was necessary to develop the IRAM method to determine the higher order modes inside the multimodo optical waveguide, since the SOR method is able to yield only the fundamental mode. In this framework, the D-shape microstructured optical fibers, which have been proposed and investigated in this work, proved to be extremely efficient for chromatic dispersion compensation and increasing the birefringent effect. Fibers have been designed in order to compensate the wideband dispersion, covering three entire telecommunication bands, namely: S-, C- and L- bands, simultaneously. Additionally, with these new proposed configurations it is possible to design high birefringent fibers, which are very attractive in polarization maintaining applications.

APA, Harvard, Vancouver, ISO, and other styles

28

Santos, Eliane Moura dos. "Processos relacionados a inserção de fluidos para sensoriamento com fibras de cristal fotônico." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278251.

Full text

Abstract:

Orientadores: Luiz Carlos Barbosa, Cristiano Monteiro de Barros Cordeiro
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
Made available in DSpace on 2018-08-11T19:12:29Z (GMT). No. of bitstreams: 1 Santos_ElianeMourados_M.pdf: 4020531 bytes, checksum: 57766702771129e7f4bfe1d0c7852f67 (MD5) Previous issue date: 2007
Resumo: Este trabalho apresenta estudos de como inserir fluidos (líquidos e gases) em fibras ópticas microestruturadas, especialmente fibras de cristal fotônico, também conhecidas como PCF¿s (do inglês Photonic Crystal Fibers). Estas fibras possuem buracos de ar que percorrem todo seu comprimento. Elas podem ser divididas em dois grandes grupos: as de núcleo sólido que guiam luz por reflexão interna total e as de núcleo oco que guiam luz por um mecanismo conhecido como photonic bandgap. Ambos os tipos de fibras permitem várias aplicações em áreas como óptica e fotônica e nos dedicamos aqui à área de sensoriamento a fibra. Nesta área, usamos os microburacos para inserir fluido e dessa maneira manipular as propriedades de guiamento (em fibras de núcleo líquido), deixar a fibra mais sensível a algum parâmetro externo ou para sensoriar o fluido em questão. Nos três casos, precisamos estudar os processos de preenchimentos de fibras microestruturadas. Para este fim, estudamos e desenvolvemos maneiras de inserir fluidos em fibras de núcleos sólidos ou ocos. Usando preenchimento seletivo, produzimos fibras com núcleo líquido, criando uma região de alta interação entre luz e material. Neste trabalho, estudamos diferentes técnicas de preenchimento. A primeira, para fibras de núcleo líquido, é um preenchimento seletivo que pode ser feito usando uma máquina de emendas (splicer) ou um polímero para bloquear os microburacos. O outro consiste em manter as pontas das fibras livres (para medidas ópticas) enquanto o preenchimento é feito. Por fim, usamos o conhecimento desses processos em aplicações como sensoriamento de fluidos ou parâmetros externos e manipulação de propriedades de guiamento da luz
Abstract: This work presents studies of how to insert fluids (liquid and gas) into microstructured optical fibers, especially photonic crystal fibers, also known as PCF¿s. These optical fibers possess air holes that run along its entire length. They can be divided into two major groups: solid core fibers that guide light by total internal reflection and hollow core fibers that guide light by photonic bandgap. Both types of fibers allow several applications in areas such as optics and photonics and we dedicated this work to the fiber-sensing field. In this area we use the micro holes to insert fluids and in this way to manipulate the guidance properties in liquid core fibers, to leave the fiber more sensitive to some external parameter or to sensing the fluid. In these three cases we need to study the filling procedures in microstructured fibers. For this purpose, we studied and developed ways of inserting fluids in hollow and solid core fibers. We produced liquid core fibers, creating a high light-material overlap, using a selective filling technique. In this work we studied different filling techniques. The first one, for liquid core fibers, is a selective filling, which can be done by using a splicer machine or a polymer to block the fiber micro holes. The last one consists of keeping the fiber tips free (for optical measurements) while the filling is done. And finally we used the filling process knowledge in applications like sensing of fluids or external parameters and manipulation of guidance properties
Mestrado
Física Geral
Mestre em Física

APA, Harvard, Vancouver, ISO, and other styles

29

Meneghetti, Marcello. "Microstructured optical fibers based on chalcogenide glasses for mid-IR supercontinuum generation." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S081.

Full text

Abstract:

Ce travail de thèse s'est déroulé dans le cadre d'un projet européen, nommé SUPUVIR, dont l'objectif est d'améliorer les sources de supercontinuum de l'ultraviolet ou moyen infrarouge (MIR). Dans ce contexte, le travail de thèse s'est concentré sur le développement et la réalisation de fibres optiques en verres de chalcogénures transparentes dans le moyen infrarouge. Plus précisément, l'objectif était de réaliser des fibres infrarouges transparentes dans la plage de longueurs d'onde allant de 2 à 12 μm avec un profil de dispersion sur mesure en associant la science du verre et des techniques innovantes de mise en forme des fibres afin de les utiliser pour la réalisation de nouvelles sources dans le moyen infrarouge. Afin de convenir à cette application, la fibre optique doit présenter le meilleur compromis entre les paramètres non linéaires (principalement contrôlés par la taille du coeur et la composition du verre), la position de la longueur d'onde de dispersion nulle (en fonction de longueur d'onde souhaitée de la pompe) et la fenêtre de transmission infrarouge. Au cours de ces travaux, des fibres microstructurées avec des verres de haute pureté ont pu être fabriquées. L'utilisation de ces fibres a permis l'obtention de supercontinua étendus de 2 à 10 µm. L'utilisation de cette source a ensuite permis la détection de signatures infrarouges d'un composé chimique et aussi montré le fonctionnement d'un spectromètre original utilisant un supercontinuum. Enfin, au cours de ces travaux de thèse, la première fibre optique à gradient d'indice en verres de chalcogénures a été fabriquée et ses propriétés de transmission et de dispersion ont été mesurées et étudiées
In the framework of the SUPUVIR project, whose objective is to improve supercontinuum sources from the ultraviolet to the mid infrared, this work is focused on the development and fabrication of mid-IR optical fibers. More specifically the objective set was to realize high quality infrared (in the 2-12 μm wavelength range) fibers based on chalcogenide glasses, with a dispersion profile tailored by combining glass sciences and innovative fiber shaping techniques, to be used for mid- IR supercontinuum generation. In order to be suitable for this application, the fiber design needs to be a best compromise between nonlinear parameters (mainly controlled by the core size and chalcogenide composition), position of the zero dispersion wavelength (depending on desired pump wavelength), power handling properties and breadth of the transmission window. In this thesis, the production and characterization of microstructured fibers is detailed, starting from the choice and purification of the most proper chalcogenide glasses up to the production of a working prototype of commercial mid infrared supercontinuum fiber source, spanning from 2 to 10 μm, and to its application to spectroscopy. In addition, the development of the first chalcogenide graded index (Grin) fiber reported in literature is described, together with its characterization and the application of its production technique to the fabrication of Grin microlenses

APA, Harvard, Vancouver, ISO, and other styles

30

Sudirman, Azizahalhakim. "Increased Functionality of Optical Fibers for Life-Science Applications." Doctoral thesis, KTH, Kvantelektronik och -optik, QEO, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-145319.

Full text

Abstract:

The objective of this thesis work is to increase the functionality of optical fibers for possible applications in life-sciences. Optical fibers are a promising technology for use in biology and medicine. They are low-costwaveguides, flexible and have a small cross-section. They can guide high-power light with low loss in a micrometer core-size. These features make fibers attractive for minimally-invasive,in-vivostudies. The backwards guidance of the optical signal allows for real-time monitoring of the distance to the scattering targets and to study the environment through Raman scattering and fluorescence excitation. The longitudinal holes introduced in the fibers can be used,for instance,for delivery of medicine to a specific regionof a body. They could even be used for the extractionof species considered interesting for further analysis, for example, studyingcells that may be cancer-related. This thesis deals with four main topics. First, a demonstration is presented of the combination of high-power light guidance for ablation, low-power light reflectometry for positioning, and for liquid retrieval in a single fiber. It was found that in order to exploit the microfluidic possibilities available in optical fibers with holes, one needs to be able to combine fluids and light in a fiber without hindering the low-loss light guidance and the fluid flow. Secondly, one should also be able to couple light into the liquids and backout again. This is the subject of another paper in the present thesis. It was also observed that laser excitation through a fiber for the collection of a low-intensity fluorescence signal was often affected by the luminescence noise createdby the primary-coating of the fiber. This problem makes it difficult to measure low light-levels, for example, from single-cells. Athirdpaper in this thesis then describes a novel approach to reduce the luminescence from the polymer coating of the fiber, with the use of a nanometer-thick carbon layer on the cladding surface. Finally, exploiting some of the results described earlier, an optical fiber with longitudinal holes is used for the excitation, identification and for the collection of particles considered being of interest. The excitation light is guided in the fiber, the identification is performed by choosing the fluorescent particles with the appropriate wavelength, and, when a particle of interest is sufficiently near the fiber-tip, the suction system is activated for collection of the particle with good specificity. It is believed that the work described in this thesis could open the doors for applications in life-sciences and the future use of optical fibers for in-vivo studies.

QC 20140516

APA, Harvard, Vancouver, ISO, and other styles

31

Hayes, John. "The fabrication and development of microstructured optical fibres for beam delivery and generation." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/386584/.

Full text

Abstract:

In this thesis I describe my work on the development and fabrication of fibres for beam delivery and generation. In all cases it is assumed the fibres will be suitable for high power applications. I describe the challenges of fabrication and refinements to existing techniques needed to produce and characterise the diverse fibres. Two jacketed air clad (JAC) fibres with square cores are developed. One is a passive delivery fibre that has capacity to capture a larger beam parameter product than other research and commercial fibres and was designed to deliver the output from a 1800 W diode source. The second jacketed air clad fibre has an inner core doped with Yb ions and a shaped pump core defined by a large NA air cladding. This gave reduced fibre length in an amplifier (compared to a conventional rare earth double clad fibre) providing an advantage with respect to the onset of non linear spectral broadening. Two all-solid photonic bandgap fibres (S-PBGF) for beam delivery from a fibre laser with a wavelength of 1070 nm and simultaneous rejection of stimulated Raman scattering (SRS) light at a wavelength of 1126 nm are presented. The fibres gave larger MFD near 1 μm with SRS suppression than other published results at the time of this work. A new type of leakage channel fibre, called the micro-clad leakage channel fibre (micro-clad LCF), is demonstrated for the first time. This fibre type is intended for both beam delivery and in future fibres with an inner core doped with rare earth ions, for beam generation. I present the fabrication and characterisation of an exemplar fibre with mode area of 1440 μm2. A class of simple antiresonant hollow core fibres are investigated. Various single cladding layer fiber structures are examined. I show that the spacing between core and jacket glass and the shape of the support struts can be used to optimize confinement loss. I demonstrate the detrimental effect on confinement loss of thick nodes at the strut intersections and present a fabricated hexagram fibre that mitigates this effect in both straight and bent condition by presenting radially aligned nodes. This fibre has loss comparable to published results for a first generation, multi-cladding ring, Kagome fibre with negative core curvature and has tolerable bend loss for many practical applications.

APA, Harvard, Vancouver, ISO, and other styles

32

Mart, Cody W. "Characterization and Power Scaling of Beam-Combinable Ytterbium-Doped Microstructured Fiber Amplifier." Thesis, The University of Arizona, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10621184.

Full text

Abstract:

In this dissertation, high-power ytterbium-doped fiber amplifiers designed with advanced waveguide concepts are characterized and power scaled. Fiber waveguides utilizing cladding microstructures to achieve wave guidance via the photonic bandgap (PBG) effect and a combination of PBG and modified total internal reflection (MTIR) have been proposed as viable single-mode waveguides. Such novel structures allow larger core diameters (>35 ?m diameters) than conventional step-index fibers while still maintaining near-diffraction limited beam quality. These microstructured fibers are demonstrated as robust single-mode waveguides at low powers and are power scaled to realize the thermal power limits of the structure. Here above a certain power threshold, these coiled few-mode fibers have been shown to be limited by modal instability (MI); where energy is dynamically transferred between the fundamental mode and higher-order modes. Nonlinear effects such as stimulated Brillouin scattering (SBS) are also studied in these fiber waveguides as part of this dissertation. Suppressing SBS is critical towards achieving narrow optical bandwidths (linewidths) necessary for efficient fiber amplifier beam combining. Towards that end, new effects that favorably reduce acoustic wave dispersion to increase the SBS threshold are discovered and reported.

The first advanced waveguide examined is a Yb-doped 50/400 μm diameter core/clad PBGF. The PBGF is power scaled with a single-frequency 1064 nm seed to an MI-limited 410 W with 79% optical-to-optical efficiency and near-diffraction limited beam quality (M-Squared < 1.25) before MI onset. To this author’s knowledge, this represents 2.4x improvement in power output from a PBGF amplifier without consideration for linewidth and a 16x improvement in single-frequency power output from a PBGF amplifier.

During power scaling of the PBGF, a remarkably low Brillouin response was elicited from the fiber even when the ultra large diameter 50 μm core is accounted for in the SBS threshold equation. Subsequent interrogation of the Brillouin response in a pump probe Brillouin gain spectrum diagnostic estimated a Brillouin gain coefficient, gB, of 0.62E^-11 m/W; which is 4x reduced from standard silica-based fiber. A finite element numerical model that solves the inhomogenous Helmholtz equation that governs the acoustic and optical coupling in SBS is utilized to verify experimental results with an estimated gB = 0.68E^-11 m/W. Consequently, a novel SBS-suppression mechanism based on inclusion of sub-optical wavelength acoustic features in the core is proposed.

The second advanced waveguide analyzed is a 35/350 μm diameter core/clad fiber that achieved wave guidance via both PBG and MTIR, and is referred to as a hybrid fiber. The waveguide benefits mutually from the amenable properties of PBG and MTIR wave guidance because robust single-mode propagation with minimal confinement loss is assured due to MTIR effects, and the waveguide spectrally filters unwanted wavelengths via the PBG effect. The waveguide employs annular Yb-doped gain tailoring to reduce thermal effects and mitigate MI. Moreover, it is designed to suppress Raman processes for a 1064 nm signal by attenuating wavelengths > 1110 nm via the PBG effect. When seeded with a 1064 nm signal deterministically broadened to ∼1 GHz, the hybrid fiber was power scaled to a MI-limited 820 W with 78% optical-to-optical efficiency and near diffraction limited beam quality of M_Squared ∼1.2 before MI onset. This represents a 14x improvement in power output from a hybrid fiber, and demonstrates that this type of fiber amplifier is a quality candidate for further power scaling for beam combining.

APA, Harvard, Vancouver, ISO, and other styles

33

Pierrot, Simonette. "Propagation non linéaire et amplification d'impulsions picosecondes dans des fibres microstructurées dopées ytterbium." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4026/document.

Full text

Abstract:

Intensivement étudié depuis son apparition en 1960, le laser est un outil qui a su trouver sa place au-delà du monde académique : ses performances uniques l'ont rendu indispensable dans nombres d'applications de la vie courante. Les particularités les plus attractives du rayonnement laser sont la directivité de son émission, et le caractère quasi-monochromatique de son rayonnement.La première permet de propager un faisceau laser sur des longues distances, et également de concentrer la lumière sur des cibles aux dimensions extrêmement réduites : on parle de cohérence spatiale de l'émission laser. Cette seule propriété trouve de nombreuses applications : les lecteurs de codes-barres, imprimantes laser, pointeurs lasers en sont des exemples très rependus.La seconde permet d'accorder la bande spectrale étroite de l’émission laser aux bandes d'absorption de certains matériaux, ce qui permet de déposer localement de l’énergie de manière contrôlée. Par ailleurs elle confère au rayonnement laser des propriétés de cohérence temporelle uniques, qui peuvent être exploitées notamment en interférométrie, ouvrant la voie à de très nombreuses applications dans le domaine de la mesure, pour la caractérisation de surfaces optiques, dans les capteurs de position à effet Sagnac, en spectrométrie, pour ne pas citer quelques exemples

APA, Harvard, Vancouver, ISO, and other styles

34

Alfeeli, Bassam. "Ionizing Radiation Resistance of Random Hole Optical Fiber for Nuclear Instrumentation and Control Applications." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/32661.

Full text

Abstract:

Random hole optical fibers (RHOF) offer advantages over other types of microstructured optical fibers (MOFs). They are inexpensive and easy-to-make when compared to the high cost of ordered hole MOFs. They also have unique characteristics since they contain open and closed holes. The open holes contain ambient air under normal conditions and the closed holes contain residual gases from the fabrication process at certain pressure. The objective of this research work was to investigate the radiation resistance of Random Hole Optical Fibers (RHOF) for possible use as both sensing element and data transmission medium in nuclear reactor instrumentation and control applications. This work is motivated by the demand for efficient, cost effective, and safe operation of nuclear power plants, which accounts for more than 14% of the worldâ s electricity production. This work has studied the effect of gamma irradiation on RHOF fibers by comparing their performance to that of standard solid telecommunication fibers and commercially available specialty solid fiber designed to be radiations hardened fiber. The fibers were evaluated at different absorbed dose levels: 12 mGy(Si), 350 mGy(Si), and 7200 Gy(Si) by measuring their radiation induced absorption (RIA) on-line. In the low dose test, the maximum RIA measured in untreated RHOF was approximately 8 dB while the RIA in the untreated MMF fibers reached a maximum at about 28 dB. In the high dose test, the maximum RIA measured in untreated RHOF was 36 dB while RIA in the methanol washed RHOF was only 9 dB. RHOF also demonstrated superior radiation damage recovery time over all of the other fibers tested. Based on the experimental evaluations, it was deduced that RHOFs used in this work are resistant to gamma radiation. and recover from radiation damage at a faster rate compared to other fibers tested. The radiation induced absorption (RIA) at the 1550 nm window in the RHOF fibers could be attributed to the OH absorption band tail. However, the existence of other mechanisms responsible for RIA is also postulated. Some of these mechanisms include bulk and surface defects which are related to the fabrication process and the influence of the gases confined within the RHOF microstructure. Gamma radiation resistance of RHOFs can be attributed to the lack of dopants and also possibly the inherent OH and nitrogen content. The behavior of thermally annealed RHOF and their fast recovery is in favor of this hypothesis.
Master of Science

APA, Harvard, Vancouver, ISO, and other styles

35

Sudirman, Azizahalhakim. "Combining Reflectometry, Ablation and Fluid Collection in a Microstructured Fiber." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-20818.

Full text

Abstract:

The purpose of the diploma work is to investigate the possibilities to combine three different areas; reflectometry, microfluidics and laser ablation in a microstructured single-mode fiber, thus obtaining a controlled technique for positioning for ablation and collection of liquids from small inclusions.

Each of the three areas is thoroughly described in different sections of this report. The first part of the experiments in this diploma work consisted of combining reflectometry and microfluidics, the second part combining reflectometry with laser ablation and the final experiment setup consisted of a combination of all three areas. An artificial system for liquid collection was then designed for that purpose.

The results obtained from experiments and measurements clearly demonstrate that combining reflectometry, laser ablation and fluid collection in a single optical fiber is promising. Future work will include improvements of the technique towards a medical application for bone marrow transplantation.

APA, Harvard, Vancouver, ISO, and other styles

36

Strutynski, Clément. "Fibres tellurites pour sources supercontinuum infrarouges : gestion des profils opto-géométriques et des absorptions extrinsèques." Thesis, Dijon, 2016. http://www.theses.fr/2016DIJOS061/document.

Full text

Abstract:

Ces travaux de thèse portent sur la synthèse et purification de matériaux vitreux utilisés pour le développement de fibres optiques à profils opto-géométriques variés, adaptées à la génération de supercontinuum (SC) entre 1 et 5 μm.Concernant la purification, plusieurs pistes ont été suivies, le meilleur résultat étant obtenu pour la purification du système vitreux TeO2-ZnO-Na2O au moyen du fluorure de zinc. Les mesures d'atténuation sur fibre mono-indice révèlent l'élimination presque complète des absorptions liées aux groupements OH entre 3 et 4 μm (taux d'impuretés OH dans la matrice inférieur à 1 ppm massique). Ces verres purifiés sont utilisés pour la fabrication de fibres optiques microstructurées (FOMs). Un élargissement spectral couvrant la fenêtre 0.6 μm - 3.3 μm est obtenu dans une fibre effilée à coeur suspendu. Aussi, une source compacte basée sur la génération de SC dans une FOM en tellurite est développée et appliquée à la détection de gaz (du méthane) entre 2 et 3 μm. Cependant un phénomène de vieillissement, lié à une interaction du coeur de la fibre avec la vapeur d'eau atmosphérique via la microstructure, et entraînant une augmentation des pertes optiques entre 3 et 4 μm, est mis en évidence dans ces fibres à coeur suspendu. Pour pallier ce problème, des fibres tout-solide à saut d’indice sont développées. La méthode de fabrication des préformes en verre, combinant les techniques de built-in casting et de rod-in-tube, est alors adaptée aux techniques de purification. Une fibre à saut d'indice à petit coeur en verres TNaGZ et TZNF purifiés a notamment été étirée et utilisée pour la génération d’élargissements spectraux dans différents régimes de dispersion
This PhD thesis work focuses on the synthesis and purification of vitreous materials used for the development of waveguides with varied profiles, dedicated to supercontinuum (SC) generation between 1 and 5 μm.Concerning the purification of tellurite glasses, several leads were followed, but best results are obtained for the purification of the TeO2-ZnO-Na2O glassy system by the means of zinc fluoride. Attenuation measurements performed on several meter-long single-index fiber samples reveal the nearly complete elimination of water-related absorptions between 3 and 4 μm (OH ions concentration lower than 1 ppm mass.). Such water-purified glasses were firstly dedicated to microstructured optical fibers (MOFs) fabrication for SC generation. Spectral broadening between 0.6 and 3.3 μm is obtained in a suspended-core taper. Moreover, a compact source based on supercontinuum generation in tellurite MOFs is developed for a gas detection application in the 2-3 μm domain. However an aging process, due to water contamination and leading to the apparition of additional optical losses between 3 and 4 μm, has been identified in those suspended-core fibers. In order to avoid such transmission degradation, all-solid step-index fibers are developed. The preforms fabrication method, which combines the built-in casting and the rod-in-tube, is adapted to the purification techniques. An all-solid small-core waveguide made from purified TNaGZ and TZNF glasses is fabricated and moreover used for spectral broadening experiments in different dispersion regimes

APA, Harvard, Vancouver, ISO, and other styles

37

Savelii, Inna. "Fibres optiques à coeur supendu en verre d'oxyde de tellure et génération d'effets non linéaires dans l'infrarouge au-delà de 2 microns." Thesis, Dijon, 2012. http://www.theses.fr/2012DIJOS086/document.

Full text

Abstract:

Les travaux réalisés dans ce manuscrit portent sur la fabrication de fibres optiques microstructurées (FOMs) à cœur suspendu en verre de tellurite pour la génération de supercontinuum au-delà de 2µm. Pour atteindre notre but nous avons tout d'abord réalisées les études des propriétés thermiques et optiques des verres TeO2-ZnO-R2O et TeO2-WO3-R2O (où R= Li, Na et K). La composition du verre 80TeO2-10ZnO-10Na2O (% molaire) a été sélectionnée pour la fabrication des FOMs destinées aux caractérisations du développement des effets non linéaires. La synthèse sous atmosphère sèche et oxydante nous a permis de réduire la concentration des groupements hydroxyles d’un facteur 30 par rapport à la fabrication du verre sous air. L’utilisation d'agents déshydratants (ZnF2 et TeCl4) permet d'abaisser encore la concentration des groupements OH jusqu’à quelques ppm. La composition du verre 80TeO2-5ZnO-5ZnF2-10Na2O donne une fibre transparente jusqu’à 4 µm laissant apparaître l’influence de l’absorption multiphonon. Utilisant les précurseurs commerciaux les plus purs nous avons pu réaliser une fibre de tellurite avec de très faibles pertes à 0,1 dB/m.Nous avons fabriqué des FOMs à cœurs suspendus avec des diamètres de cœurs variant de 2,7 µm à 3,5 µmet permettant de gérer la dispersion chromatique et de ramener la longueur d'onde du zéro dispersion entre 1500 nm et 1660 nm. Pour optimiser la génération du supercontinuum nous avons utilisé des sources laser pulsées pico- et femtosecondes pour pomper les fibres en régime de dispersion anormale. En parallèle aux mesures expérimentales, nous avons effectué des modélisations numériques basées sur la résolution de l'équation de Schrödinger non-linéaire généralisée. Les résultats expérimentaux, en bon accord avec les simulations, nous ont permis d'obtenir un élargissement spectral s’étalant de 850 nm à 2850 nm avec un niveau de puissance de sortie de 112 mW, dont l'extension à plus grandes longueurs d'ondes dans l'infrarouge est encore pour l'instant fortement limitée par l’absorption des groupements hydroxyles. Cependant la déshydratation du matériau, même si elle doit encore être améliorée a permis de montrer que lors de pompage à 2000-2200 nm le supercontinuum peut atteindre 4000-4500 nm, gamme de longueurs d’onde à partir de laquelle l’absorption multiphonon commence à être perceptible
The work reported in this thesis deals with the fabrication of suspended core tellurite microstructured optical fibers (MOFs) for supercontinuum generation beyond 2 µm. In order to reach our aim, we first studied thermal and optical properties of TeO2-ZnO-R2O and TeO2-WO3-R2O (where R = Li, Na and K) glasses. The glass 80TeO2-10ZnO-10Na2O (molar %) has been chosen in order to make MOFs for characterization of the generated non linear optical effects. Synthesis performed under dry and oxidative atmosphere allowed us to reduce the hydroxyl groups concentration by a factor of 30 compared to fabrication in air atmosphere. Use of dehydrating agents (ZnF2 and TeCl4) allowed to reduce again the OH groups concentration down to a few ppm. The glass composition 80TeO2-5ZnO-5ZnF2-10Na2O increases the fiber transparency up to 4 µm letting the influence of multiphonon absorption appear. Using the purest commercial raw powders, we have fabricated one tellurite fiber exhibiting very low losses (0,1 dB/m). We have fabricated suspended core MOFs with a core diameter varying from 2,7 µm up to 3,5 µm allowing to deal with the chromatic dispersion and to shift the zero dispersion wavelength down to the 1500-1660 nm range. In order to optimize the supercontinuum generation, we have used pico- and femtosecondes pulsed laser sources to pump the fibers in anomalous dispersion regime. In parallel to the experimental measurements, we have performed numerical simulations based on the resolution of the generalized nonlinear Schrödinger equation. The experimental results, in good agreement with the simulations, allowed us to point out a spectral broadening expending from 850 nm up to 2850 nm with a total output power of 112 mW, with an extinction near the longest infrared wavelengths which is again strongly limited by the hydroxyl groups absorption. However, the dehydrated material, even though it needs to be improved further, allowed to show that by pumping at 2000-2200 nm, the supercontinuum can reach 4000-4500 nm, the wavelength range from which the multiphonon absorption starts to be perceptible

APA, Harvard, Vancouver, ISO, and other styles

38

Hey, Tow Kenny. "Laser Brillouin à fibre microstructurée en verre de chaleogénure." Phd thesis, Université Rennes 1, 2013. http://tel.archives-ouvertes.fr/tel-00860216.

Full text

Abstract:

Souvent considéré néfaste dans le domaine de la télécommunication car il limite la puissance d'un système de transmission optique, l'effet Brillouin peut être utilisé pour la réalisation de lasers. Un laser à fibre Brillouin peut potentiellement être très cohérent et très peu bruité ; ce qui incite son utilisation dans plusieurs domaines incluant la défense, la métrologie et les télécommunications. L'objectif de cette thèse, qui s'insert dans le cadre du projet ATOS (Antenne acoustique en technologie Tout Optique pour la Surveillance), est d'obtenir un laser Brillouin à la fois compact et avec un seuil laser relativement bas. Pour respecter ces deux conditions, il est nécessaire de disposer d'une ﬁbre avec un très fort coefficient de gain Brillouin gB et ayant une très petite aire effective de manière à concentrer la puissance optique dans le cœur de la fibre. Nous avons ainsi choisi d'utiliser une fibre faite à partir de verres en chalcogénure, qui ont un gB de deux ordres de grandeurs supérieures au gB d'une fibre monomode silice classique avec une microstructure dans le coeur. Ces travaux de recherche contribuent donc, d'une part, à démontrer qu'il est expérimentalement possible de réaliser des lasers Brillouin compacts, bas seuils et exhibant des caractéristiques remarquables en termes de bruit et de cohérence avec des fibres microstructurées en verre de chalcogénure et, d'autre part, à étudier la potentialité de ces cavités lasers dans le cadre du projet ATOS tout en proposant d'autres applications possibles pour la métrologie, l'instrumentation et les télécommunications.

APA, Harvard, Vancouver, ISO, and other styles

39

Jollivet, Clemence. "Specialty Fiber Lasers and Novel Fiber Devices." Doctoral diss., University of Central Florida, 2014. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6295.

Full text

Abstract:

At the Dawn of the 21st century, the field of specialty optical fibers experienced a scientific revolution with the introduction of the stack-and-draw technique, a multi-steps and advanced fiber fabrication method, which enabled the creation of well-controlled micro-structured designs. Since then, an extremely wide variety of finely tuned fiber structures have been demonstrated including novel materials and novel designs. As the complexity of the fiber design increased, highly-controlled fabrication processes became critical. To determine the ability of a novel fiber design to deliver light with properties tailored according to a specific application, several mode analysis techniques were reported, addressing the recurring needs for in-depth fiber characterization. The first part of this dissertation details a novel experiment that was demonstrated to achieve modal decomposition with extended capabilities, reaching beyond the limits set by the existing mode analysis techniques. As a result, individual transverse modes carrying between ~0.01% and ~30% of the total light were resolved with unmatched accuracy. Furthermore, this approach was employed to decompose the light guided in Large-Mode Area (LMA) fiber, Photonic Crystal Fiber (PCF) and Leakage Channel Fiber (LCF). The single-mode performances were evaluated and compared. As a result, the suitability of each specialty fiber design to be implemented for power-scaling applications of fiber laser systems was experimentally determined. The second part of this dissertation is dedicated to novel specialty fiber laser systems. First, challenges related to the monolithic integration of novel and complex specialty fiber designs in all-fiber systems were addressed. The poor design and size compatibility between specialty fibers and conventional fiber-based components limits their monolithic integration due to high coupling loss and unstable performances. Here, novel all-fiber Mode-Field Adapter (MFA) devices made of selected segments of Graded Index Multimode Fiber (GIMF) were implemented to mitigate the coupling losses between a LMA PCF and a conventional Single-Mode Fiber (SMF), presenting an initial 18-fold mode-field area mismatch. It was experimentally demonstrated that the overall transmission in the mode-matched fiber chain was increased by more than 11 dB (the MFA was a 250 ?m piece of 50 ?m core diameter GIMF). This approach was further employed to assemble monolithic fiber laser cavities combining an active LMA PCF and fiber Bragg gratings (FBG) in conventional SMF. It was demonstrated that intra-cavity mode-matching results in an efficient (60%) and narrow-linewidth (200 pm) laser emission at the FBG wavelength. In the last section of this dissertation, monolithic Multi-Core Fiber (MCF) laser cavities were reported for the first time. Compared to existing MCF lasers, renown for high-brightness beam delivery after selection of the in-phase supermode, the present new generation of 7-coupled-cores Yb-doped fiber laser uses the gain from several supermodes simultaneously. In order to uncover mode competition mechanisms during amplification and the complex dynamics of multi-supermode lasing, novel diagnostic approaches were demonstrated. After characterizing the laser behavior, the first observations of self-mode-locking in linear MCF laser cavities were discovered.
Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics and Photonics

APA, Harvard, Vancouver, ISO, and other styles

40

Alhenc-Gelas, Claire. "Etude de la conversion de fréquence par amplification paramètrique dans les fibres optiques transparentes dans l'infrarouge." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00676557.

Full text

Abstract:

De nombreuses applications militaires ou civiles, telles que la spectroscopie dans les bandes de transmission de l'atmosphère (bandes 3-5µm et 8-12µm), nécessitent de disposer de sources émettant dans le moyen infrarouge (IR). Les travaux de cette thèse portent sur la génération de rayonnement dans la bande 3-5µm par amplification paramétrique (mélange à quatre ondes) dans les fibres optiques en verres fluorés et en verres de chalcogénures. La première partie de ce travail a été consacrée à l'étude théorique et à la modélisation des conditions d'accord de phase et du gain paramétrique dans des fibres à saut d'indice monomodes en verres fluorés ZBLAN et verres de chalcogénures As2S3 et As2Se3. La nature des résultats obtenus nous a conduit à étudier théoriquement le potentiel de l'accord de phase multimode dans les fibres en verres de chalcogénures. La deuxième partie de ce travail a porté sur la modélisation de l'amplification paramétrique dans des fibres en verres de chalcogénures microstructurées à géométrie hexagonale. Pour ce faire, un modèle simplifié de la propagation dans les fibres microstructurées hexagonales a été développé : le modèle de l'indice effectif de gaine (EIM). Il a ensuite été comparé à une méthode de résolution aux éléments finis. Grâce à cette comparaison, nous avons pu améliorer la précision du modèle EIM en déterminant la valeur de plusieurs paramètres empiriques. Ce modèle nous a alors permis de prédire l'efficacité du processus d'amplification paramétrique dans les fibres microstructurées. L'ensemble de ces études théoriques a permis d'identifier les fibres les plus adaptées à la conversion de fréquence vers la bande 3-5µm. Enfin, nous avons réalisé un banc de mesure de la dispersion chromatique des fibres, ainsi que le dimensionnement d'un convertisseur de fréquence utilisant les fibres identifiées dans l'étude théorique.

APA, Harvard, Vancouver, ISO, and other styles

41

Stiller, Birgit. "Brillouin scattering in photonic crystal fiber : from fundamentals to fiber optic sensors." Thesis, Besançon, 2011. http://www.theses.fr/2011BESA2019/document.

Full text

Abstract:

Le cadre général dans lequel s’insère ce travail de thèse est celui de l’étude de la diffusion Brillouin dans une nouvelle génération de fibres optiques à cristaux photoniques (PCFs). Ces fibres, qui présentent un arrangement périodique de micro-canaux d’air parallèles le long de la fibre, possèdent en effet des propriétés optiques et acoustiques remarquables et inédites par rapport aux fibres conventionnelles. De façon plus précise, nous montrons dans ce travail, par le biais de simulations numériques et de données expérimentales, que les fibres à cristaux photoniques offrent la possibilité de supprimer ou, à contrario, augmenter les interactions entre les photons et les phonons. Dans une première partie, nous présentons une méthode de cartographie des fluctuations longitudinales de la microstructure des fibres PCFs à l’aide d’un capteur distribué basé sur une méthode innovante d’écho Brillouin. Cette méthode, très sensible et à haute résolution, est directement intéressante pour caractériser et améliorer l’uniformité des PCFs lors de leur fabrication et également pour la détection des différentes contraintes de température et étirement induites le long des fibres. Sur le plan fondamental, notre système de mesure distribuée à haute résolution nous a également permis d’observer, pour la première fois à notre connaissance, le temps de vie des ondes acoustiques dans les fibres à cristaux photoniques et les fibres standard. Par ailleurs, sur le plan technique, nous avons développé une architecture simplifiée de capteur distribué combinant la technique des échos Brillouin et celle de la modulation différentielle par déplacement de phase avec un seul modulateur d’intensité. Nos résultats montrent une résolution centimétrique dans la zone de soudure entre deux fibres optiques à l’aide d’une impulsion de phase de 500 ps. Nous démontrons dans une deuxième partie la suppression directe et passive de la rétrodiffusion Brillouin stimulée dans une fibre optique micro structurée en faisant varier périodiquement le diamètre de la microstructure. Une augmentation de 4 dB du seuil de puissance Brillouin a été obtenue avec une variation de seulement 7% sur une période de 30m. Ce résultat est très intéressant car la diffusion Brillouin est un facteur limitant dans les systèmes de télécommunications par fibre optique et les lasers à fibre. La troisième et dernière partie est consacrée à l’étude numérique et expérimentale de la diffusion Brillouin en avant dans les fibres à cristaux photoniques. En plus de la suppression de la plupart des modes acoustiques transverses, nous montrons que cette diffusion Brillouin est fortement augmentée pour certains modes acoustiques à haute fréquence qui sont piégés au cœur de la microstructure. Nous avons également étudié une fibre à structure multi-échelle qui révèle l’excitation sélective de plusieurs phonons acoustiques à des fréquences allant jusqu’a 2GHz. Ces mesures ont étés confirmées par des simulations numériques basées sur une méthode vectorielle aux éléments finis. L’impact des irrégularités de la microstructure a aussi été mis en évidence.Mots clés : optique non linéaire, diffusion Brillouin, fibres optiques microstructurées, seuil Brillouin, capteurs Brillouin distribués
Brillouin scattering is a fundamental nonlinear opto-acoustic interaction present in optical fibers with important implications in fields ranging from modern telecommunication networks to smart optical fiber sensors. This thesis is aimed at providing a comprehensive theoretical and experimental investigation of both forward and backward Brillouin scattering in next generation photonic crystal fibers in view of potential applications to above mentioned fields. We show in particular that these micro-structured optical fibers have the remarkable ability to either suppress or enhance photon-phonon interactions compared to what is commonly observed in conventional fibers. Firstly, this thesis provides a complete experimental characterization of several photonic crystal fibers using a novel highly-resolved distributed sensing technique based on Brillouin echoes. We perform distributed measurements that show both short-scale and long-scale longitudinal fluctuations of the periodic wavelength-scale air-hole microstructure along the fibers. Our mapping technique is very sensitive to structural irregularities and thus interesting for fiber manufacturers to characterize and improve the fiber uniformity during the drawing process. With this technique, we also report the first experimental observationof the acoustic decay time and the Brillouin linewidth broadening in both standard and photonic crystal fibers. Furthermore, we experimentally demonstrate a simplified architecture of our Brillouin echoes-based distributed optical fiber sensor with centimeter spatial resolution. It is based on differential phase-shift keying technique using a single Mach-Zehnder modulator to generate a pump pulse and a _-phase-shifted pulse with an easy and accurate adjustment of delay. These sensing techniques are also applied to distributed strain measurement. Another aspect of this thesis is the investigation of a novel method for suppressing stimulated Brillouin scattering that is detrimental to optical fiber transmissions and fiber lasers. We experimentally study several fibers and a demonstrate 4 dB increase of the Brillouin threshold in a photonic crystal fiber by varying periodically the core diameter by only7%. The efficiency of this passive technique is verified by use of our distributed sensing technique where the oscillating Brillouin frequency shift is clearly observed.Lastly, we present experimental and numerical results demonstrating the simultaneous vi Abstract frequency-selective excitation of several guided acoustic Brillouin modes in a photonic crystal fiber with a multi-scale structure design. These guided acoustic modes are identified by using a full vector finite-element model to result from elastic radial vibrations confined by the air-silica microstructure. We further show the strong impact of structural irregularities of the fiber on the frequency and modal shape of these acoustic resonances

APA, Harvard, Vancouver, ISO, and other styles

42

Doherty, Brenda [Verfasser], Markus A. [Gutachter] Schmidt, Rachel [Gutachter] Grange, and Isabelle Philippa [Gutachter] Staude. "Plasmonic microstructured optical fibres : an efficient platform towards biosensing / Brenda Doherty ; Gutachter: Markus A. Schmidt, Rachel Grange, Isabelle Philippa Staude." Jena : Friedrich-Schiller-Universität Jena, 2020. http://d-nb.info/121099853X/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Miraglia, Rodrigo Cesar Ribeiro. "Modelagem numérica de uma fibra óptica microestruturada para sensoriamento distribuído de pressão." Universidade Presbiteriana Mackenzie, 2010. http://tede.mackenzie.br/jspui/handle/tede/1394.

Full text

Abstract:

Made available in DSpace on 2016-03-15T19:37:31Z (GMT). No. of bitstreams: 1 Rodrigo Cesar Ribeiro Miraglia.pdf: 2147088 bytes, checksum: 67087392fe4b03bb24d9a164fd92ceed (MD5) Previous issue date: 2010-08-20
Fundo Mackenzie de Pesquisa
Sensors based on optical fibers are being increasingly used in hostile environments for measuring pressure, temperature, stress, chemical and biological parameters, etc. These sensors have the advantage of having reduced size and weight, immunity to electromagnetic interference, of being chemically inert, and also allowing the distributed measurement of the respective parameter along the fiber. Microstructured optical fibers have characteristics that are relevant to sensing applications, such as freedom of design of their internal structure obtained by varying the diameter of the holes and the distances between them, among other parameters, which is not applicable in conventional optical fibers. The present work aims to use a microstructured optical fiber as a distributed sensor for hydrostatic pressure, using the POTDR (Polarization Optical Time-Domain Reflectometry) and the OFDR (Optical Frequency-Domain Reflectometry) measurement techniques. The application of hydrostatic pressure on the fiber changes its birefringence and, consequently, the evolution of the states of polarization, which is the parameter monitored by the techniques. By monitoring the changes of these states, it is possible to infer the changes in applied pressure. The study is undertaken via simulations and analysis, both performed in the software MatLab.
Sensores baseados em fibras ópticas vêm sendo cada vez mais utilizados em ambientes hostis para medição de pressão, temperatura, stress, análise química e biológica, etc. Esses sensores têm a vantagem de possuírem tamanho e peso reduzidos, imunidade à interferência eletromagnética, de serem quimicamente inertes, e também permitirem a medição distribuída do parâmetro a ser analisado ao longo da fibra. As fibras ópticas microestruturadas possuem características relevantes na aplicação de sensoriamento, tal como a liberdade de construção de sua estrutura interna variando o diâmetro dos buracos e a distância entre eles, entre outros parâmetros, que não são aplicáveis em fibras ópticas convencionais. Este trabalho tem como objetivo estudar uma fibra óptica microestruturada como sensor distribuído de pressão hidrostática, utilizando as técnicas de medição POTDR (Polarization Optical Time-Domain Reflectometry) e OFDR (Optical Frequency-Domain Reflectometry). A aplicação de pressão hidrostática sobre a fibra altera sua birrefringência e, consequentemente, a evolução do seu estado de polarização, sendo este último o parâmetro monitorado pelas técnicas. Analisando-se a mudança deste estado, pode-se inferir a mudança de pressão aplicada. O estudo é realizado através de simulações e análises efetuadas no software MatLab.

APA, Harvard, Vancouver, ISO, and other styles

44

Araujo, Alfredo Almeida de. "Análise de amplificação Raman em fibras microestruturadas de baixa perda." Universidade Presbiteriana Mackenzie, 2008. http://tede.mackenzie.br/jspui/handle/tede/1485.

Full text

Abstract:

Made available in DSpace on 2016-03-15T19:38:07Z (GMT). No. of bitstreams: 1 Alfredo Almeida Araujo.pdf: 1307305 bytes, checksum: fd5b49227c52b28ef3a5392983927234 (MD5) Previous issue date: 2008-02-13
This dissertation aims to describe the basic characteristics of microstructured fibers, their concept and performance, and to investigate the application of a low loss microstructured fiber to the development of Raman amplifiers. An analysis of the use of these amplifiers in Telecommunication applications is described. To this end, simulations were carried out with these waveguides with the data of a real fiber described in the literature. Simulations were also carried out to determine the amplifier s net gain and noise figure and to establish the advantages of its use in a complete optical fiber span, including the compensation dispersion in the O band (1260-1360 nm). As a result, it was demonstrated that the microstructured fiber presents, in some aspects, a performance that is higher than that of conventional Raman amplifiers, and complementary to that of a commercial amplifiers, such as those based on Erbium doped fiber.
Esta dissertação tem como objetivo descrever as características básicas das fibras microestruturadas, seu conceito e desempenho, e investigar a aplicação de uma fibra microestruturada de baixa perda para o desenvolvimento de amplificadores Raman. Uma análise do uso destes em aplicações de Telecomunicações é descrita. Para isso, foram realizadas simulações destes guias de onda com dados de uma fibra real descrita na literatura. Também foram realizadas simulações para verificação do ganho líquido e figura de ruído de um amplificador baseado nesta fibra e das vantagens de seu uso em um enlace óptico completo, incluindo compensação de dispersão para sinais da banda O (1260-1360 nm). Como resultado, demonstrou-se um desempenho superior em alguns aspectos aos amplificadores Raman convencionais, e complementar aos amplificadores disponíveis atualmente no mercado, como os baseados em fibra dopada com Érbio.

APA, Harvard, Vancouver, ISO, and other styles

45

Ramos, Gonzales Roddy Elky. "Técnica para controlar o comprimento de onda da dispersão zero de uma fibra microestruturada." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260813.

Full text

Abstract:

Orientador: Hugo Enrique Hernández Figueroa
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
Made available in DSpace on 2018-08-22T14:17:05Z (GMT). No. of bitstreams: 1 RamosGonzales_RoddyElky_D.pdf: 101751842 bytes, checksum: 8dc15b7e91881cfef8e1c24fa619f3ca (MD5) Previous issue date: 2013
Resumo: Propor uma técnica eficiente para controlar o Comprimento de Onda da Dispersão Zero (ZDW - Zero Dispersion Wavelength) de uma Fibra Óptica Microestruturada (MOF - Microstructured Optical Fiber). Esta técnica baseia-se na variação do índice de refração linear e na variação da espessura de um filme fino que cobre as superfícies interiores dos buracos da MOF. Foi utilizado um código potente e preciso baseado na formulação do Método dos Elementos Finitos (FEM - Finite Element Method) totalmente vetorial em conjunto com Camadas Perfeitamente Casadas (PMLs - Perfectly Matched Layers). E demonstrado um deslocamento Maximo do ZDW de 570 nm. Este filme fino pode ser incluído durante ou apos a fabricação da MOF, isso significa que a Dispersão Zero (ZD - Zero Dispersion) da fibra pode ser adaptada conforme a necessidade
Abstract: An efficient technique to control the zero-dispersion wavelength (ZDW) of a microstructured optical fiber (MOF) is proposed and numerically demonstrated in this work. This technique is based on the variation of the linear refractive index and the thickness of a thin film covering the microstructured optical fiber holes' inner surfaces. A powerful and accurate code based on a full-vector finite-element method formulation in conjunction with perfectly matched layers was used. A maximum of 570-nm zero-dispersion wavelength displacement is demonstrated. This thin film can be included after the microstructured optical fiber has been fabricated, and that means the zero dispersion of such fiber can be tailored as needed
Doutorado
Telecomunicações e Telemática
Doutor em Engenharia Elétrica

APA, Harvard, Vancouver, ISO, and other styles

46

Gunawidjaja, Ray. "Organic/inorganic nanostructured materials towards synergistic mechanical and optical properties /." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29733.

Full text

Abstract:

Thesis (Ph.D)--Industrial and Systems Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Tsukruk, Vladimir; Committee Member: Bucknall, David; Committee Member: Kalaitzidou, Kyriaki; Committee Member: Shofner, Meisha; Committee Member: Tannenbaum, Rina. Part of the SMARTech Electronic Thesis and Dissertation Collection.

APA, Harvard, Vancouver, ISO, and other styles

47

Ramos, Igor da Silva. "Análise sistêmica da compensação de dispersão e amplificação Raman em fibras microestruturadas." Universidade Presbiteriana Mackenzie, 2009. http://tede.mackenzie.br/jspui/handle/tede/1501.

Full text

Abstract:

Made available in DSpace on 2016-03-15T19:38:12Z (GMT). No. of bitstreams: 1 Igor da Silva Ramos.pdf: 1622777 bytes, checksum: 186a77eaabf846baf8466f41da580a23 (MD5) Previous issue date: 2009-02-03
Fundo Mackenzie de Pesquisa
This work studies, through systemic modeling a microstructured optical fiber used in a module for dispersion compensation and Raman amplification for optical communication systems. The use of this device compensates the dispersion in a range of frequencies not covered by conventional dispersion compensating fibers and, simultaneously, amplifies the signal in order to reach longer transmission distances. In particular, dispersion compensation and amplification is demonstrated in the O Band (1260 nm up to 1360 nm) for systems operating at 10 and 40 Gbps. For this purpose, the parameters of a real microstructured optical fiber model are used in the VPI TransmissionMaker numerical simulation software through which is possible to evaluate the performance of the device. The performance evaluation is carried out through Bit Error Rate (BER) as a function of link distance and transmission channel wavelength.
Este trabalho estuda através de modelamento sistêmico, uma fibra óptica microestruturada utilizada em um módulo de compensação de dispersão e amplificação Raman de sistemas ópticos. O uso deste dispositivo compensa a dispersão em faixas de freqüência não cobertas por fibras de compensação de dispersão convencionais e simultaneamente amplifica o sinal a fim de permitir maiores distâncias de transmissão. Em particular, compensação de dispersão e amplificação são demonstradas na banda O (1260 nm a 1360 nm) para sistemas operando a taxas de 10 e 40 Gbps. Para isso, são utilizadas as características de um modelo de fibra microestruturada real no software de simulação numérica VPI TransmissionMaker por meio do qual é possível avaliar o desempenho deste dispositivo. A avaliação de desempenho é feita através de curvas de taxa de erro de bits (BER, do inglês Bit Error Rate) em função do comprimento do enlace e comprimento de onda do canal de transmissão.

APA, Harvard, Vancouver, ISO, and other styles

48

Palavicini, Cham Carlos Alberto. "Analyse de composants photoniques par réflectométrie à faible cohérence sensible à la phase." Phd thesis, Télécom ParisTech, 2004. http://pastel.archives-ouvertes.fr/pastel-00000751.

Full text

Abstract:

L'émergence des amplificateurs à fibre et l'inévitable accroissement du débit ont drastiquement augmenté la complexité des systèmes de transmission optiques, imposant une évolution des composants photoniques. Des techniques de caractérisation fiables et précises sont alors indispensables pour mener une analyse appropriée des caractéristiques et des performances desdits composants. La réflectométrie à faible cohérence sensible à la phase est une technique bien adaptée à la détection, localisation et quantification des discontinuités d'indice dans les composants optiques et photoniques. Dans le cadre de cette thèse, elle a été appliquée à l'analyse de différents composants photoniques innovants, tels que les réseaux de Bragg à fibre, les fibres optiques spéciales et les lasers à semi-conducteurs soumis à une injection optique. Les résultats obtenus situent cette technique comme un véritable outil d'investigation qui s'avère très performant pour l'assistance et l'aide à la conception des nouvelles générations de composants photoniques.

APA, Harvard, Vancouver, ISO, and other styles

49

Baillot, Maxime. "Mélange à quatre ondes multiple pour le traitement tout-optique du signal dans les fibres optiques non linéaires." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S068/document.

Full text

Abstract:

Le mélange à quatre ondes est un effet non linéaire sensible à la phase qui suscite de nombreux intérêts dans le domaine de la génération de peignes de fréquences et du traitement tout optique du signal par exemple. Un peigne de fréquences peut en effet s'obtenir par effet de mélange à quatre ondes 1en cascade. Dans ce cas, un nombre N d'ondes interagissent entre elles via l'effet Kerr et la modélisation d'un tel processus doit tenir compte de tous les couplages possibles entre les ondes. Au cours de mes travaux de thèse, je me suis intéressé, dans un premier temps, à la modélisation du mélange à quatre ondes dit multiple pour lequel un nombre quelconque N d'ondes interagissent entre elles. J'ai proposé une formulation générale permettant d'identifier simplement tous les termes de mélange à quatre ondes issus de toutes les combinaisons possibles de couplage entre les ondes et leur désaccord de phase associé. J'ai validé cette approche en proposant une étude théorique et expérimentale d'un processus de mélange à quatre ondes multiple dans une fibre optique non linéaire. Dans une deuxième partie, j'ai proposé, grâce au modèle élaboré précédemment, une étude théorique du phénomène de conversion de fréquence sensible à la phase, permettant la décomposition des composantes en quadrature d'un signal optique. Dans la littérature, cette expérience fut démontrée initialement avec quatre ondes pompes et dans plusieurs types de composants non linéaires. J'ai pu démontrer, au cours de mes travaux, que trois pompes étaient suffisantes pour réaliser l'expérience et j'ai déterminé des relations analytiques simples permettant de choisir les paramètres expérimentaux (notamment l'amplitude et la phase des pompes) rendant possible la décomposition des composantes en quadrature d'un signal. J'ai validé cette étude par la démonstration expérimentale d'un convertisseur de fréquence sensible à la phase avec uniquement trois pompes et j'ai étudié théoriquement les effets de la dispersion chromatique sur les performances du convertisseur de fréquence. Enfin, dans une dernière partie, j'ai caractérisé des fibres optiques microstructurées en verre de chalcogénure fabriquées dans le cadre d'une collaboration avec Perfos, l'Institut des Sciences Chimiques de Rennes et SelenOptics. Dans ce cadre, j'ai mis en place un banc de mesure de la dispersion chromatique et du coefficient non linéaire des fibres optiques basé sur le mélange à quatre ondes
Four-wave mixing is a phase-sensitive nonlinear effect that arouses interest, particularly in the fields of frequency comb generation and all-optical signal processing. As an example, frequency combs can be produced thanks to a cascaded four-wave mixing process. In this case, N waves can interact with each other through the optical Kerr effect, and one has to take into account all the possible interactions to be able to adequately model the process. During my PhD thesis, I was interested in modeling the so-called multiple four-wave mixing process, in which any number N of waves can interact with each other. I proposed a general formulation that allows to easily identify all the four-wave mixing terms originating from all the possible combinations of wave coupling and their associated phase-mismatch terms. I validated this approach through the theoretical and experimental study of a multiple four-wave mixing process in a nonlinear optical fiber. Thanks to the developed model, I then proposed a theoretical study of the phase-sensitive frequency conversion process, which permits to demultiplex the quadrature components of an optical signal. In the literature, this process was first experimentally demonstrated in several nonlinear devices using four pump waves. I demonstrated that only three pump waves were required to successfully perform the experiment, and I determined the simple analytical relations from which the adequate experimental parameters (namely, the amplitudes and phases of the pump waves) could be deduced. I finally validated this study by experimentally demonstrating a phase-sensitive frequency conversion process with only three pump waves, and I theoretically studied the influence of chromatic dispersion on the performance of this frequency converter. Finally, I characterized some chalcogenide microstructured optical fibers that were fabricated in the framework of a collaboration with Perfos, the Institut des Sciences Chimiques de Rennes, and SelenOptics. I set up a test bench based on the four-wave mixing process in order to measure the chromatic dispersion and nonlinear coefficient of some optical fibers

APA, Harvard, Vancouver, ISO, and other styles

50

Henrique, Franciele Renata. "Conexão óptica de microestruturas poliméricas através de nanofibras." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-25042016-093740/.

Full text

Abstract:

O desenvolvimento da fotônica integrada vem recebendo muita atenção nos últimos anos. Sua alta funcionalidade e velocidade de transmissão de sinais possibilitam a aplicação em diversas áreas, que vão desde comunicações até biologia. O uso de polímeros em circuitos fotônicos integrados tem se mostrado interessante, pois compostos orgânicos podem ser facilmente incorporados a matrizes poliméricas. Isso faz com que as propriedades físicas do polímero possam ser modificadas de acordo com os materiais incorporados. Além disso, a técnica da fotopolimerização por absorção de dois fótons torna possível a produção de microestruturas poliméricas tridimensionais com alta resolução. A incorporação dessas microestruturas a circuitos fotônicos pode trazer um novo ramo de funcionalidades devido à facilidade de modificação das propriedades dos polímeros. Além disso, a tridimensionalidade das estruturas permite a realização de conexões ópticas em três dimensões, o que colabora para o aumento da compacticidade dos dispositivos fotônicos. No entanto, para que estas microestruturas possam ser efetivamente incorporadas aos circuitos fotônicos é necessário desenvolver formas de conectá-las a fontes externas de excitação, bem como a instrumentos de análise de sinais. Os tapers de fibras ópticas, também conhecidos como microfibras ou nanofibras, são bons candidatos para realizar essa tarefa devido a suas dimensões reduzidas, as quais são compatíveis com o tamanho das microestruturas. Neste trabalho desenvolvemos métodos para realizar a conexão óptica entre microestruturas poliméricas e tapers de fibras ópticas. As microestruturas foram produzidas através da técnica de fotopolimerização por absorção de dois fótons e corantes orgânicos foram incorporados à matriz polimérica para conferir propriedades fluorescentes às estruturas. Os tapers foram produzidos a partir de fibras ópticas convencionais por uma técnica de aquecimento e estiramento. Para realizar a conexão óptica, dois métodos foram desenvolvidos. No primeiro deles as microestruturas foram excitadas através de uma lente objetiva e sua emisão foi coletada por um taper. No segundo método, tanto a excitação quanto a coleta foram realizadas por tapers de fibras ópticas. Em ambos os casos as fibras foram posicionadas através de micromanipuladores. Os resultados obtidos indicam que os tapers são ferramentas adequadas para realizar tanto a excitação quando a coleta da emissão de microestruturas, pois permitem excitação individual e coleta localizada. Produzimos microestruturas com múltiplas dopagens e pudemos concluir que a excitação localizada de diferentes partes da estrutura, bem como a correta escolha do comprimento de onda de excitação, são mecanismos que levam a alterações no espectro de emissão, o que torna estas estruturas candidatas a fontes de luz sintonizáveis que podem ser incorporadas a dispositivos on-chip. Por fim, desenvolvemos um método de produção de microestruturas conectadas a tapers. Este trabalho abre caminho para a incorporação de microestruturas poliméricas a circuitos fotônicos e demonstra que tapers de fibras ópticas são ferramentas eficientes para a realização de microconexões ópticas.
The development of integrated photonics has received a great deal of attention in the last few years. Its high functionality and signal transmission speed allow applications in several fields, from telecommunications to biology. The use of polymeric platforms in integrated photonic circuits is interesting because organic compounds can be easily incorporated to polymeric matrixes, which makes it easy to change the physical properties of the polymer according to the embed materials. Furthermore, the two-photon polymerization technique allows the production of three-dimensional polymeric microstructures with high resolution. The incorporation of these microstructures to photonic circuits paves the way for a new field of funcionalities due to the ease of modification of the polymers properties. Besides that, the structures three-dimensionality allows the performance of optical connections in three dimensions, which can improve the compacticity of the photonic devices. However, for the effective incorporation of these microstructures to photonic circuits, it is necessary to develop ways to connect them to external excitation sources, as well as analysis instruments. Optical fiber tapers, also known as microfibers or nanofibers, are good candidates for this task due to their reduced dimensions that are compatible with the size of the microstructures. In this work we developed methods for the performance of optical connections of polymeric microstructures through fiber tapers. The microstrutures were produced through the two-photon polymerization technique and organic dyes were incorporated to the polymeric matrix in order to introduce fluorescent properties. The fiber tapers were produced from conventional optical fibers through a heat-and-draw approach. To perform the optical connections, two methods were developed. In the first one, the microestructures were excited through a microscope objective and emission collection was performed by a fiber taper. In the second approach, excitation and collection were performed by fiber tapers. In both methods, the tapers were set up by micromanipulators. The obtained results indicate that tapers are a suitable tool to perform optical excitation and emission collection in microstructures, as they allow individual excitation and localized collection. Multiple doped microstructures were produced and we could imply that the localized excitation of different parts of the structures, as well as the correct choice of the excitation wavelength, are tools that lead to changes in the emission spectrum, which makes these structures candidates to tunable light sources that can be incorporated to on-chip devices. At last, we developed a method for the production of microstructures connected to fiber tapers. This work paves the way for the incorporation of polymeric microstructures to photonics circuits and demonstrates that fiber tapers are efficient tools to perform optical microconnections.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Microstructured optical fibre'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles