This thesis describes developments in the fabrication and applications of photonic microcells (PMCs). A PMC is a length of gas-filled hollow core-photonic crystal fibre (HC-PCF) that is hermetically sealed by splicing both ends to standard single mode fibre. A PMC enables integration of gas-filled HC-PCF into all-fibre systems with low insertion loss. PMCs have applications in coherent optics and metrology, where specific HC-PCF designs are advantageous. Two types of state-of-the-art HC-PCF, double bandgap HCPCF and large-pitch Kagome fibre, are fabricated. The double bandgap HC-PCF extends the usable bandwidth of the fibre by providing low loss guidance across two transmission bands. The large-pitch Kagome HC-PCF has a record low attenuation of 0.3 dB/m at 800 nm, while maintaining broadband guidance, which is partially attributed to the core shape. Three distinct developments in the field of PMCs are described. Firstly, a record length 20 metre acetylene-filled PMC is fabricated which is the key component in the first demonstration of an all-fibre slow and fast light system based on electromagnetically induced transparency. Secondly, a technique based on fibre tapering is presented which enables low loss integration of large core Kagome HC-PCFs into PMC form. Thirdly, micromirrors are developed and integrated with HC-PCF to confine light in the longitudinal dimension, providing a means to fabricate multi-pass PMCs. Two uncoated micromirrors are used to form a low finesse microcavity in Kagome HC-PCF, with record high fringe visibility using reflections from a silica/air junction. In collaboration with Kansas State University, an acetylene optical reference with sub-10 KHz accuracy and the first acetylene laser based on population inversion are demonstrated using Kagome HC-PCF.Finally, this thesis reports on rubidium vapour loading in HC-PCF with the ultimate aim being the production of a rubidium-filled PMC for applications in metrology. Preliminary results highlight the limited loading distance of the current technique and modified loading schemes are outlined accordingly.

Le besoin fondamental de cette étude est de pouvoir prévoir fidèlement le comportement de la structure finale de fil, basée sur le comportement physique et les propriétés mécaniques sous différentes charges appliquées de l'éventail de structures disponibles. Au delà du caractère scientifique de la prévision, on peut utiliser le même fondement informatisé pour simuler virtuellement les tests et expériences de laboratoire (prédiction de nouveau matériau technique) ou pour générer des animations réalistes à caractères artistiques (design de textile habillement). Par conséquent, modéliser et prédire les différents comportements dans la chaîne de création textile par l’outil informatique fournit un gain de temps et de main d'œuvre considérables. La simulation des essais de laboratoire de produits textiles dans le secteur habillement peut par la suite mener à des produits améliorés, conduire à des taux plus élevés de succès de produit ou réduire la quantité de produits invendus, et entraîner au final une hausse du chiffre d'affaire. Par l'infographie, il est possible de mettre en œuvre une chaîne virtuelle de tests comparatifs de produits utilisant une norme spécifique basée sur des critères de qualité de la simulation obtenue. Le côté novateur de notre travail de recherche est la structure variable-même du diamètre des fibres. Voilà comment, le modèle réel du fil est simulé, par la présentation préliminaire d’une structure 2D qui simule la variation des diamètres du fil et après par la présentation 3D de celle-ci, et le moyen dont la variation est construite, par la répétition de la portion simulée. L’utilisation des courbes d’interpolation représentées par les polynômes Bézier dans le cadre de ce travail, correspond à une nouvelle approche, surtout dans le domaine de la variation par section des fils type laine peignée.Dans ce contexte on a obtenu ainsi un modèle valable du fil, modèle qui est souhaitable à être étendu et validé aussi pour d’autres types de fils. L’objectif principal de ce travail est de compléter les recherches réalisées dans le cadre des applications de modélisation et simulation textile. Par l’utilisation des outils 3D, les entreprises peuvent réduire le temps nécessaire à l’amélioration des produits. Les conséquences immédiates sont la réduction des coûts et des heures de travail. L’augmentation de la puissance et de la vitesse des technologies de calcul, mais aussi la réduction de leur prix, font possible la mise en œuvre des outils virtuels pour améliorer le niveau réaliste et technique de la qualité des simulations. / The basic need of this study, would be to predict accurately yarn structure behavior based on the physical behavior and mechanical properties under different loads applied to the range. Beyond the scientific nature of the forecast, we can use the same computer to simulate virtually ground tests and laboratory experiments (prediction of new material technology) or to generate realistic animation art characters (design of textiles and clothing).Therefore, to model and to predict the different behavior in the chain of textile design by the a tool provides a gain of time and considerable manpower. Simulation of laboratory tests for textile products in the clothing industry may eventually lead to improved products, lead to higher rates of successful or reduce the amount of unsold goods, and lead ultimately to an increase in sales. In computer graphics, it is possible to implement a virtual chain of comparative testing using a specific standard based on criteria of quality obtained by simulation. The innovative aspect of our research is the generation of a structure with a variable diameter structure. The real model of the yarn is simulated by presenting a preliminary 2D structure that simulates the change in diameter and after the 3D presentation of it, the repetition of the simulated part is also an important part.The use of interpolation curves represented by Bezier polynomials in the context of this work represents a new approach, especially in the area of natural yarns sectional variation.In this context we obtained a valid model of the yarn in order to extended and validated theother one that are allready developed The main objective of this work is to complement research conducted in the framework of modeling and simulation applications textiles. By using 3D tools, companies can reduce the time required for product improvement. The immediate consequences are the reduction of costs and working hours. The increased power and speed of computing technologies, but also reducing their prices, make possible the implementation of virtual tools to improve the realistic level of quality and technical simulations.

Digital pulse position modulation (PPM) is a transmission format that can be used to exchange excess channel bandwidth for improved receiver sensitivity. This thesis is concerned with the performance of digital PPM for use in optical fibre systems such that increased single-span transmission distances can be achieved. It includes a literature survey and a thorough theoretical investigation into uncoded directly detected and coherently detected digital PPM, along with an evaluation of forward error correction coded PPM. Original contributions are described for digital PPM systems employing PIN-BJT transimpedance and PIN -FET high impedance pre-amplifiers. In the PIN -BJT case, a new analysis is presented that accounts for the band-limiting effect of the preamplifier and the non-white noise power spectral density, resulting from equalisation. For the PIN-FET, a causal noise-whitening filter is considered and the factors that limit the maximum bit-rate determined. By using an upper Chernoff Bound to the average binary error probability, results are calculated for APD-BJT and APD-FET PPM systems. The practical implementation of the optimal PPM filter is considered and two novel techniques are described for automating the realisation process. Coherent PPM is investigated and new work is presented for Reed-Solomon coded homodyne PPM. The influence of the Reed-Solomon code rate on receiver sensitivity is studied and it is shown that a 3/4 code rate leads to optimum sensitivity. Digital PPM employing soliton pulses is examined and it is shown that, under ideal conditions, a higher bit-rate than PCM can be achieved. The influence of timing jitter, associated with soliton pulse energy fluctuations and the Gordon-Haus effect, on the performance of digital PPM is investigated. The simplification of the PPM pre-detection filter is studied and a range of suboptimum filters investigated. The calculations demonstrate that the optimal predetection filter can be replaced by a simple 3rd order filter without incurring a severe sensitivity penalty. The sensitivity results of the various digital PPM systems investigated in this thesis are compared to those of equivalent PCM systems. It is illustrated that digital PPM offers an improvement of between 5-10 dB depending upon which coding format/ detection technique is employed. This represents an increase in transmission distance of 25-50 km and demonstrates that digital PPM is a promising modulation format and has potential for future high performance telecommunication routes.

Delivering high bandwidth to the individual household or small business is currently a major bottleneck in the high speed network, a problem referred to as the last mile issue. Multimode fibre is widely deployed in the last mile for cost reasons. Recently, the tremendous high-speed data transport potential of multimode fibre has been demonstrated by utilizing offset launch techniques and a laser source. However, modal noise, caused by interference among the various propagating modes of a multimode fibre in the presence of mode selective loss, is a significant roblem when a laser source is employed. This thesis investigates several aspects of modal noise for what we believe to be the first time. By utilizing single mode fibre launching, modal noise is measured at different transverse offset launching positions with both continuous wave and pulse waveform input at several different fibre lengths. Modal noise is also measured for both waveforms in conjunction with a multimode optical fibre taper in an “in line” configuration, and timing jitter is investigated for the case of pulse waveform input. Performance improvements are found in some offset positions with the fibre taper in line. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2007-11-15 09:37:44.887

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This study presents the results of an investigation to develop a novel sensor which would give a direct indication of the extent of impact damage in a composite. This was achieved by using glass reinforcing fibres to produce a light-guide, which was embedded within a composite laminate. The laminate was then subjected to impact events or bending stresses of sufficient magnitude to cause damage. The impact energies used in this study varied between 2 and 10 Joules, and the indentation depths varied between 0.125 and 1 mm, allowing damage propagation to be monitored. The fall-off in the transmitted light was used to monitor the level of damage, along with C-scanning and sectioning to provide reference data. The use of reinforcing fibres to produce the sensor meant that the strains required to cause failure in the fibres was realistically close to those of the composite constituents. Changes in the transmission characteristics of the sensor were found to correspond to real failure events occurring during impact.

The mechanical properties of alumina trihydrate (ATH)-filled epoxy resin at loadings of up to 100 parts by weight ATH per hundred of resin (epoxy and hardener) (pphr) have been investigated. A low peak exotherm, increased Young's modulus and increased critical strain energy release rate (G[sub]IC) and critical stress intensity factor (K[sub]IC) can be achieved by incorporating a dispersion of ATH into an epoxy resin. However, the high filler loadings required for effective fire resistance reduce tensile strength and elongation. Tensile modulus increases with filler loading in line with previous studies and theoretical equations. However, the tensile strength is higher and the ultimate elongation lower than current theories predict. The tensile and fracture process in ATH-filled epoxy follows linear elastic fracture mechanics, but can be considered in two parts. The initiation of a crack occurs from a large critical flaw, either as a large particle or agglomerations of particles. A flaw can also be formed on the application of a tensile load, when large stress concentrations cause localised microcracking of the matrix. The propagation of a flaw requires more energy and is dependent on several possible mechanisms. Shear yielding and associated crack blunting are shown to be the most important mechanisms, whilst minor contributions from matrix microcracking and debonding of ATH particles are possible. The absence of crack pinning in this study is believed to be due to the inherently weak nature of ATH particles. The presence of a 10pphr rubber dispersion in ATH-filled epoxy only increases the values of G[sub]IC and K[sub]IC at low filler loadings. Amine-terminated butadiene acrylonitrile rubber (ATBN)-modified epoxy matrix exhibits little adhesion to ATH and therefore the efficiency of stress transfer between particle and matrix is reduced, diminishing shear yielding.

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