Q-Band Millimeter-Wave Antennas: An Enabling Technology for MultiGigabit Wireless Backhaul

[EN] The bandwidth demands in mobile communication systems are growing exponentially day by day as the number of users has increased drastically over the last five years. This mobile data explosion, together with the fixed service limitations, requires a new approach to support this increase in bandwidth demand. Solutions based on lower-frequency microwave wireless systems may be able to meet the bandwidth demand in a short term. However, with the small-cell mass deployment requiring total capacities of 1 Gb/s/km2, scalable, multigigabit backhaul systems are required. Millimeter-wave technology fits nicely into these new backhaul scenarios as it provides extended bandwidth for high-capacity links and adaptive throughput rate, which allows efficient and flexible deployment. Besides these advantages, millimeter-wave solutions become even more attractive when the cost of backhaul solutions and the cost of spectrum licenses are factored in. Compared to the cost of laying fiber to a cell base station, which is the only other scalable solution, the millimeter-wave solution becomes the most appropriate approach.The research leading to these results received funding from the European Commission's seventh Framework Programme under grant agreement 288267.Vilar Mateo, R.; Czarny, R.; Lee, ML.; Loiseaux, B.; Sypek, M.; Makowski, M.; Martel, C.... (2014). Q-Band Millimeter-Wave Antennas: An Enabling Technology for MultiGigabit Wireless Backhaul. IEEE Microwave Magazine. 15(4):121-130. https://doi.org/10.1109/MMM.2014.2308769S12113015

Matériaux artificiels pour l'optique diffractive

Cette thèse s'intéresse aux optiques diffractives blazées binaires, une famille d'éléments diffractifs composés de structures binaires de dimensions variables mais légèrement inférieures à la longueur d'ondes. Leur principe de fonctionnement est basé sur la synthèse de matériaux artificiel, compsés de traits, de piliers ou d'autres géométries gravèés dans une couche mince diélectrique, dont l'indice effectif dépend du taux de remplissage local de la matière. Ainsi, en variant localement ce taux, il est possible de synthétiser toute fonction de phase. L'objet de cette thèse est d'identifier l'intrêt des matériaux artificiels pour des applications en optique diffractive, domaine en forte croissance avec le progrés des nanotechnologies. Tout d'abord, les résultats expérimentaux dans le visible ont montré que, dans le domaine résonnant, les optiques blazées binaires présentent des performances bien meilleures que les optiques diffractives classiques grâce à un effet de guidage par les structures sub-longueur d'onde constituant les matériaux artificiels...This work concerns blazed binary diffractive optics, a family of diffractive elements composed of binary structures with variable size that is slightly smaller than the wavelength. Their principle of operation is based on artificial materials, composed of ridges, pillars or other simple geometries etched in an dielectric thin film, which effective index depends on the fill factor. Thus, by varying locally the fill factor, one cansynthesize any phase function. The objet of the study is to identify tha advantage of artificial materials for applications in diffractive optic, a domain that is highly increasing with the nano-technology improvements.First, the experimental results obtained in the visible have shown that, in the resonance domain, blazed binary optcs offer higher performances than the standard diffrative optics. It is due to a guiding effect through the sub-wavelength structures that compose the artificial matérials.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Broadband blazing with artificial dielectrics

International audienceThe efficiency of conventional diffractive optical elements with échelette-type profiles drops rapidly as the illumination wavelength departs from the blaze wavelength. We use high dispersion of artificial materials to synthesize diffractive optical elements that are blazed over a broad spectral range ( 1 octave) or for two different wavelengths

Conception conjointe de l’optique et du traitement d’image appliquée à l’athermalisation d’un objectif infrarouge (Orale)

National audienc

New solutions and technologies for uncooled infrared imaging

International audienceThe military uncooled infrared market is driven by the continued cost reduction of the focal plane arrays whilst maintaining high standards of sensitivity and steering towards smaller pixel sizes. As a consequence, new optical solutions are called for. Two approaches can come into play: the bottom up option consists in allocating improvements to each contributor and the top down process rather relies on an overall optimization of the complete image channel. The University of Rennes I with Thales Angénieux alongside has been working over the past decade through French MOD funding's, on low cost alternatives of infrared materials based upon chalcogenide glasses. A special care has been laid on the enhancement of their mechanical properties and their ability to be moulded according to complex shapes. New manufacturing means developments capable of better yields for the raw materials will be addressed, too. Beyond the mere lenses budget cuts, a wave front coding process can ease a global optimization. This technic gives a way of relaxing optical constraints or upgrading thermal device performances through an increase of the focus depths and desensitization against temperature drifts: it combines image processing and the use of smart optical components. Thales achievements in such topics will be enlightened and the trade-off between image quality correction levels and low consumption/ real time processing, as might be required in hand-free night vision devices, will be emphasized. It is worth mentioning that both approaches are deeply leaning on each other. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only