Semiconductor ring laser diodes (SLD) have been receiving attention for their potential use as source in photonic integrated circuits. Advantages of a ring laser include ease of integration because of no need for cleaved facets and they can be made very compact by folding their cavity . Ring laser have a unique feature, clockwise and counter- clockwise, in their lasing modes. If unidirectional traveling-wave oscillation can be achieved, spatial hole burning effects seen in Fabry-Perot and distributed feedback lasers can be avoided. In this work, the unidirectional oscillation is accomplished by controlling the taper shape structure. The whole laser cavity is formed using four reflection mirrors (TIR) and an output coupler passive waveguide. According to the Beam propagation Method (BPM) simulation, we find that the clockwise and counterclockwise oscillations have different behavior under various taper shape , indicating bidirectional oscillation can be eliminated. Moreover, bending loss¡Bmode transformation and optical gain are all included in calculation model. The waveguide is fabricated in the following steps: (1) ion implantation to get electrical isolation (2) selectively wet etching to form waveguide ridge (3) evaporation n- and p- electrode (4)spatter with Si3N4(5) planarization (6) evaporation microwave transmission line.

Les matériaux composites jouent un rôle de plus en plus important dans notre société et dans de très nombreux domaines (aéronautique, naval, génie civil…), grâce à leurs avantages en terme de légèreté, d’inaltérabilité et de rigidité. Cependant, ils présentent des faiblesses qui peuvent poser des problèmes au niveau de leur utilisation pour les ouvrages de génie civil. Ces faiblesses concernent notamment leur durabilité. A cause des phénomènes viscoélastiques, les propriétés mécaniques des structures en composites évoluent dans le temps. Le fluage et/ou la relaxation sont des facteurs importants qui peuvent considérablement affecter l’application des composites aux structures. Dans ce travail de doctorat, on effectue une analyse sur le comportement à court et à long terme des composites unidirectionnels renforcés par des fibres de verre/carbone. Afin d’obtenir des résultats quantitatifs sur le comportement mécanique de ces composites, différents types des sollicitations mécaniques seront considérés (ex. compression, cisaillement, tension, flexion). Les analyses sont basées sur deux modèles micromécaniques développés par l'équipe MSA. Le premier modèle est de type shear-lag viscoélastique et le deuxième utilise le logiciel éléments finis Abaqus. Ces deux modèles prennent en compte les différents micro-mécanismes de rupture comme la rupture des fibres, la décohésion des fibres/matrice et le fluage de la résine. Plusieurs analyses numériques sont faites afin de valider les différentes hypothèses de la théorie shear-lag. A partir des analyses menées, des améliorations sont apportées sur le modèle type shear lag. Une étude comparative avec les éléments finis a permis de bien valider les résultats obtenus par la méthode shear-lag. Ayant calibré nos modèles type shear-lag et éléments finis, des simulations types court et long terme sont faites sur des composites unidirectionnels renforcées par des fibres de verre et de carbone. Les analyses sont réalisées sur plusieurs échantillons pour chaque type de fibre (Simulation de Monte-Carlo) / Fiber Reinforced Plastic materials (FRP) are beginning to find more and more applications in the civil engineering domain. Besides the use of FRPs for the reinforcement of existing structures, these materials are utilized quite often today for the construction of bridges and even for new buildings made entirely of FRPs. At the matter of fact, the light weight of composite materials is a considerable advantage compared to conventional materials such as steel or concrete. Another advantage is that they have outstanding fatigue and durability potential and that they are in general very tolerant to environmental effects such as UV radiations, moisture, chemical attack and extreme temperature variations. However, the lack of a comprehensive, validated, and easily accessible database for the durability of fiber-reinforced polymer composites as related to civil infrastructure applications is a critical barrier to their usage as main load bearing systems. The creep behavior of these materials and their failure under sustained loads remains an open research topic. This study gives a detailed analysis on the mechanical behavior of unidirectional fiber reinforced composites (UD FRP) subjected to different loading patterns (tension, compression, shear, and flexure). We develop two micromechanical models that allow us to analyze the instantaneous and the long term response of UD composites subjected to different load patterns. The first model is based on the shear-lag theory and the Beyerlein et al.[1998] developments while the second one is established using the finite element software Abaqus. A Comparative study between the two models allowed to validate the fundamental assumptions of the shear-lag theory (first model) as well as several numerical issues related to time integration and spatial discretization. The Monte Carlo method is used in order to account for the stochastic fiber strength and its impact on the ultimate tensile strength (short term) and creep (long term). A parametric investigation on the fiber type and load level/type on the short/long term behavior of UD composites is also presented