Volume diffraction gratings for optical telecommunications applications: design study for a spectral equalizer

The main characteristics required for a diffraction grating used for demultiplexing functions in spectral equalizing systems are investigated, both theoretically and experimentally. We show that volume-phase holographic (VPH) gratings can be used as dispersive elements instead of classic reflection surface-relief gratings presently employed in most optical telecommunications devices. A design method for this type of diffraction grating and experimental results are presented, confirming that VPH gratings are well suited to such applications

Rapid prototyping of diffractive optical elements in microstructured sol-gel hybrid material

International audienceTELECOM Bretagne and HOLOTETRIX Company fabricate diffractive optical elements in photoresist by direct-write through a reconfigurable mask. The project is to transfer microstructured patterns of photoresist element to sol-gel hybrid material. This material offers better properties than photoresist to make diffractive optics

Microstructuration de matériaux polymères pour la fabrication de composants optiques diffractifs

2 pagesNational audienceL'objectif de l'étude est la fabrication d'éléments optiques diffractifs (EODs), performants et répondant aux besoins actuels des industriels, selon un procédé simple à mettre en oeuvre, reproductible et pour un coût raisonnable. Pour cela, le matériau retenu est un sol-gel hybride de la famille des ORMOCER®s compte tenu de ses performances attrayantes (transparence, stabilités thermique, chimique et mécanique). L'élément final est créé par moulage à partir d'un EOD en photorésine obtenu par photolithographie à écriture directe parallèle à 436 nm. Le procédé mis en place, optimisé et validé repose sur de nombreuses caractérisations structurelles et fonctionnelles. Il conduit aujourd'hui à une nouvelle génération d'EODs présentant des efficacités de diffraction à l'ordre 0 inférieures à 1%

Multiplexer and variable optical attenuator based on PDLC for polymer optical fiber networks

In this work, a combination of a multiplexer and a variable optical attenuator in the same device (VMUX) for use in Polymer Optical Fiber is proposed. Polymer Dispersed Liquid Crystals (PDLC) are polarization independent, have high contrast and gray scale capability. For these reasons, PDLC cells with pixels can be used as switching elements in the device. Characterization of the PDLC has been carried out at two wavelengths. VMUX Complete switching is reached for driving voltages of 20 Vrms, with insertion losses less than 1.6 dB, attenuation larger than 31 dB, rise time less than 2.6 ms and decay time better than 12.4 ms have been obtained.This work was supported in part by CICYT (TIC2003-03783 and TEC2006-13273-C03-03-MIC), in part by UC3M (FAVICOBIS), in part by CAM (FACTOTEM-CM:S-0505/ESP/000417), and in part by COST 299.Publicad

Phototraceur UV à micro-miroirs pour la réalisation de fonctions optiques integrées et diffractives

session Me2 " Instrumentation, Caractérisation et Capteurs " [Me2.3]National audienceLe sujet concerne la réalisation d'un phototraceur utilisant un écran à micro-miroirs (DMD : Digital Micro-mirror Device) fonctionnant dans l'UV entre 300 et 400 nm. Ce phototraceur permet la photo-inscription directe dans des polymères de fonctions optiques intégrées et/ou d'éléments diffractifs

Deep time and first settlement: What, if anything, can linguistics tell us?

ABSTRACT FOR THE BOOK: Nowhere on Earth is there an ecological transformation so swift and so extreme as between the snow-line of the high Andes and the tropical rainforest of Amazonia. The different disciplines that research the human past in South America have long tended to treat these two great subzones of the continent as self-contained enough to be taken independently of each other. Objections have repeatedly been raised, however, to warn against imagining too sharp a divide between the people and societies of the Andes and Amazonia, when there are also clear indications of significant connections and transitions between them. Rethinking the Andes–Amazonia Divide brings together archaeologists, linguists, geneticists, anthropologists, ethnohistorians and historians to explore both correlations and contrasts in how the various disciplines see the relationship between the Andes and Amazonia, from deepest prehistory up to the European colonial period. The volume emerges from an innovative programme of conferences and symposia conceived explicitly to foster awareness, discussion and co-operation across the divides between disciplines. Underway since 2008, this programme has already yielded major publications on the Andean past, including History and Language in the Andes (2011) and Archaeology and Language in the Andes (2012)