Search

This paper exposes a comparative study that was made between the adaptive particle swarm optimization (APSO) and the hybrid model genetical swarm optimizer approaches (GSO) for the synthesis of 1-D equally spaced annular ring antenna arrays for both TM11 and TM12 modes. The synthesis of 1-D uniform antenna arrays is designed as a mono objective problem. The employed optimization techniques are compared in terms of convergence rate and side lobes level reduction. Several original numerical results are provided to demonstrate the performance of the proposed techniques. The results reveal that the suggested array antenna synthesis approach using genetical swarm optimizer outperforms the adaptive particle swarm optimi zation in terms of side lobes level reduction and convergence rate.

In this paper an 8-channel demultiplexer has been proposed and simulated based on 2D photonic crystals for WDM and DWDM applications. The obtained quality factors are the best according to litterator until now and are between 4430 and 10363.33. The average transmission efficiency and average bandwidth are 94.31% and 0.239 nm respectively. Crosstalk values are low and range from − 18 dB to − 65.5 dB. Ring resonators as the basic structure for the design of the final demultiplexer structure are used to separate the optical waves. The proposed demultiplexer is a square array of dielectric rods of gallium arsenic GaAs with a refractive index of 3.37, operates around 1.55 µm. The designed device has a lattice constant equal to 610 nm and a fill factor equal to 0.2. To simulate our structure, we used COMSOL Multiphysics based on the finite element method. The proposed demultiplexer has a narrow average spacing of 1 nm with a small footprint of 461.76 µm2 that can be exploited in optical integrated circuits.

In this letter, a novel and original configurations of highly efficient 1×3 and 1×6 beam splitters based on a photonic crystal with wide operating frequency band over the wavelength range, respectively (1.519-1.569) μm and (1.544-1.564) μm for terahertz communication applications are proposed. This is the most important results found in terms of transmission ever seen from these two devices in comparison with the literature. It is found that the efficient total transmissions of ~99.9% and 96% for the 1 × 3 and 1 × 6 splitters, respectively, with very low insertion losses at output ports are obtained around the wavelength of 1.55 μm. The simulation results confirm that the current designs can provide an efficient splitting over a broad bandwidth of ~50 nm for 1 × 3 splitter and 20 nm for the 1 × 6 splitter, respectively.

Two dimensional finite differences temporal domain (2D-FDTD) numerical simulations are performed in cartesian coordinate system to determine the dispersion diagrams of transverse electric (TE) of a two-dimension photonic crystal (PC) with triangular lattice. The aim of this work is to design a filter with maximum spectral response close to the frequency 1.55 μm. To achieve this frequency, selective filters PC are formed by combination of three waveguides W1K A wherein the air holes have of different normalized radii respectively r1/a=0.44, r2/a=0.288 and r3/a= 0.3292 (a: is the periodicity of the lattice with value 0.48 μm). Best response is obtained when we insert three small cylindrical cavities (with normalized radius of 0.17) between the two half-planes of photonic crystal strong lateral confinement.

Ce travail se rapporte à l’analyse numérique de l’implémentation des formats de modulation en phase dans les futurs systèmes de transmission sur fibre optique. Deux types de séquences de données ont été générés et étudiés afin de modéliser les transmissions aux formats QPSK. Les outils numériques utilisés sont Matlab/OCEAN basés respectivement sur l’analyse des séquences et la simulation de la propagation guidée d’un signal optique. Les résultats de simulation obtenus concernant l’impact sur la qualité de transmission des effets non-linéaires combinés avec la dispersion chromatique inhérents à la propagation optique sont présentés et discutés

Les cristaux photoniques sont des matériaux nano-structurés dont les tailles caractéristiques submicroniques permettent un contrôle sans précédent du confinement de la lumière et rendent possible la miniaturisation des principales fonctions optiques. Justement, cette thèse constitue un ensemble de travaux qui s’appuie sur la conception et le développement de nouveaux composants à base des cristaux photoniques pour des applications dans les communications et le traitement du signal optique à haute cadence et de leur intégration au sein de circuits photoniques en utilisant une méthode qui repose sur la résolution des équations de Maxwell aux différences finies dans le domaine temporel bidimensionnel FDTD-2D. Cette dernière permettra de percevoir aisément les mécanismes mis en jeu dans ces structures. Des dispositifs à cristaux photoniques tels que les guides mono rangée W1KA, à trois rangées omises W3KA, les doubles virages à 60°, les jonctions en Y 1×2 et 1×4 ainsi que les filtres sont élaborés afin de réaliser des fonctions tout-optique complexes et attrayantes. Plusieurs diagrammes de bandes sont calculés et présentés pour les structures carrées et triangulaires en employant la méthode des ondes planes pour le choix des paramètres d’entrées du cristal photonique (indice de réfraction, taille du motif). L’intégration de ces différents éléments au sein de "circuits optiques" s’avèrent une approche très prometteuse pour le traitement énergétiquement efficace de quantités de plus en plus importantes des données.

The goal of this paper is to design and optimize compact Photonic Crystal structure used for routing light. In particular, we focus on the design of a brick that will form the PhCs network, ie a waveguide W1KA and double bends. Photonic crystals are considered a good way for realizing compact optical waveguides and bend. The PhC consists of a triangular array of holes etched into InP/GaInAsP/InP heterostructure. Propagation characteristics of proposed devices are analyzed utilizing two-dimensional finite difference time domain (FDTD) method. The FDTD method will easily perceive the mechanisms involved in these devices. The PhCs transmission properties are then presented and discussed.

In this paper, we investigate the quality of the transmission of each channel for a Wavelength Division Multiplexed (WDM) system with a 640 GB/s data rate (16 x 40 GB/s) with RZ modulation for different channel spacing.