Download or read book Etude des tats excitoniques dans les nanostructures cylindriques de semi conducteurs written by Serge Le Goff and published by . This book was released on 1992 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les boîtes quantiques de semi-conducteurs sont des hétérostructures qui, pour des dimensions de l'ordre du rayon excitonique, conduisent à une quantification totale de l'énergie de l'exciton. Leur intérêt pratique réside surtout dans leurs propriétés optiques non linéaires et la perspective de réalisation de microlasers. Tandis que la géométrie sphérique décrit assez bien les microcristallites obtenues par voie chimique dans une matrice de verre, la géométrie cylindrique est mieux adaptée aux boites de petites dimensions obtenues par dépôt moléculaire suivi d'une microgravure. Nous présentons les résultats du premier calcul variationnel de l'énergie de l'état fondamental d'un exciton dans un puits quantique cylindrique fini. Nous nous sommes placés dans l'approximation de la fonction enveloppe, qui conduit à une équation de Schrodinger effective à deux particules, où entrent en compétition les potentiels de confinement de l'électron et du trou et le potentiel coulombien décrivant leur interaction. Le confinement a d'abord été modélisé par des puits carrés infinis et ensuite par des puits carrés finis. Le comportement est qualitativement différent pour les très petites dimensions : dans le premier modèle, les effets de confinement l'emportent sur l'interaction coulombienne, tandis qu'en puits fini, le rôle du potentiel de confinement n'est plus prédominant pour des dimensions de boîtes tendant vers zéro, mais pour des dimensions de boîtes de l'ordre du rayon excitonique

Download or read book ICREEC 2019 written by Ahmed Belasri and published by Springer Nature. This book was released on 2020-06-10 with total page 659 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights peer reviewed articles from the 1st International Conference on Renewable Energy and Energy Conversion, ICREEC 2019, held at Oran in Algeria. It presents recent advances, brings together researchers and professionals in the area and presents a platform to exchange ideas and establish opportunities for a sustainable future. Topics covered in this proceedings, but not limited to, are photovoltaic systems, bioenergy, laser and plasma technology, fluid and flow for energy, software for energy and impact of energy on the environment.

Download or read book Organic Solid State Lasers written by Sébastien Forget and published by Springer. This book was released on 2013-07-03 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic lasers are broadly tunable coherent sources, potentially compact, convenient and manufactured at low-costs. Appeared in the mid 60’s as solid-state alternatives for liquid dye lasers, they recently gained a new dimension after the demonstration of organic semiconductor lasers in the 90's. More recently, new perspectives appeared at the nanoscale, with organic polariton and surface plasmon lasers. After a brief reminder to laser physics, a first chapter exposes what makes organic solid-state organic lasers specific. The laser architectures used in organic lasers are then reviewed, with a state-of-the-art review of the performances of devices with regard to output power, threshold, lifetime, beam quality etc. A survey of the recent trends in the field is given, highlighting the latest developments with a special focus on the challenges remaining for achieving direct electrical pumping of organic semiconductor lasers. A last chapter covers the applications of organic solid-state lasers.

Download or read book Laser 50 Years Of Discoveries written by Fabien Bretenaker and published by World Scientific. This book was released on 2014-10-27 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: This unique book provides an overview of the principle and applications of lasers enriched with numerous illustrations.Being over fifty years old, lasers continue to amaze us. Their performance characteristics are constantly reaching new limits, and the scope of their applications continues to expand. Yet, it took years of effort by teams of physicists to transform the fundamental notions of Einstein into the first experimental beam of laser light. And history is still going on as fundamental research is now triggered by its remarkable properties.This book addresses every aspects of laser light, from its fundamental principles to its industrial applications, at a level particularly suited for high school teachers, students, and anybody curious about science and technology.

Download or read book Forest Fire Research written by Universidade de Coimbra and published by . This book was released on 2010 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: