Réseaux de diffraction à multicouches diélectriques pour la compression d'impulsions petawatt par mosaïques de réseaux.

Pulse compression diffraction gratings represent currently an important bottleneck for the development of energetic high-intensity Petawatt laser. Indeed, the laser-induced damage threshold of standard gold-coated gratings and the diffraction efficiency are limited. That's why we have developed a new generation of diffraction gratings: ! multilayer dielectric (MLD) gratings. Studies of MLD g! ratings applied to the Pico2000 laser project are the first part of my thesis work. On the other hand, diffraction gratings for pulse compression need to have meter-scale size. As an alternative of large dimension gratings, we have studied the principle of grating tiling by coherent addition. Tiled grating experiments with an interferometric technique are presented and also the demonstration of multi-Terawatt pulse compression by grating tiling. The last topic concerned the temporal control of Pico2000 laser pulse for the petawatt regime: temporal contrast and spectral pulse shaping.Les réseaux de diffraction pour la compression d'impulsions constituent actuellement un verrou technologique pour le développement des chaînes laser de puissance énergétiques dans le régime Petawatt. En effet, la tenue au flux laser et les dimensions des réseaux métalliques actuels sont limitées. C'est pourquoi, une nouvelle génération de réseaux de diffraction à multicouches diélectriques (MLD) a été développée. Ce travail d'étude et de caractérisation des réseaux MLD pour le laser Petawatt Pico2000 du LULI constitue la première partie de ma thèse. D'autre part, les réseaux de diffraction pour la compression d'impulsions Petawatt doivent avoir des dimensions de l'ordre du mètre, ce qui complique les procédés de fabrication et de caractérisation. Comme alternative! aux grands réseaux, le concept de la mise en phase de réseaux de diffraction a été étudié. Les différents résultats obtenus sur la mise en phase en lumière monochromatique par technique interférométrique sont exposés ainsi que la démonstration de la compression d'impulsions multi-terawatt par mosaïques de réseaux. Une étude du contrôle temporel des impulsions du laser Pico2000 a également été réalisée, portant sur la thématique du contraste temporel et sur la mise en forme spectrale des impulsions

Réseaux de diffraction à multicouches diélectriques pour la compression d'impulsions petawatt par mosaïques de réseaux

PALAISEAU-Polytechnique (914772301) / SudocSudocFranceF

Nonlinear temporal pulse cleaning of a 1-μm optical parametric chirped-pulse amplification system

International audienceWe demonstrate the technique of cross-polarized wave (XPW) generation at 1 μm with a 310-fs optical parametric chirped-pulse amplification system at the millijoule level. We show an improvement of the temporal contrast by three orders of magnitude with an energy transmission of 22%. Additionally, we report that XPW generation preserves the beam spatial quality and shortens the pulse duration by a factor of 3^1/2, resulting in a peak power transmission of ∼35%

From mixed flow reactor to column experiments and modeling: Upscaling of calcite dissolution rate

International audienc

Pump-noise transfer in optical parametric chirped-pulse amplification

International audienceWe report on direct observation of temporal contrast degradation of short pulses amplified by optical parametric chirped-pulse amplification. We show that, despite injection seeding, quantum-noise-induced fast modulations 50 ps of the temporal profile of the pump pulse are imprinted on the spectrum of the amplified chirped pulse and give rise to a large picosecond pedestal in the time domain

Developments of high damage threshold meter-scale optical components for multi-PW lasers

International audienc

Nonlinear temporal pulse cleaning for high-energy petawatt-class lasers

International audienceWe present a new nonlinear solid-state technique for temporal femtosecond pulses cleaning. The contrast reaches 10^-10 for millijoule input pulse. Efficiency is demonstrated at 800 nm and 1 μm. The method is reliable enough to solve the contrast issue for Petawatt class lasers

Développement de composants optiques de grande taille pour laser multi-PW

National audienc

High Damage Threshold Meter-scale Optical Components for Multi-PW Lasers

International audienc

OZCAR : The French Network of Critical Zone Observatories

[Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAU [ADD1_IRSTEA]Hydrosystèmes et risques naturels [Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAU [ADD1_IRSTEA]Hydrosystèmes et risques naturelsSpecial Section: Hydrological ObservatoriesInternational audienceThe French critical zone initiative, called OZCAR (Observatoires de la Zone Critique-Application et Recherche or Critical Zone Observatories-Application and Research) is a National Research Infrastructure (RI). OZCAR-RI is a network of instrumented sites, bringing together 21 pre-existing research observatories monitoring different compartments of the zone situated between "the rock and the sky," the Earth's skin or critical zone (CZ), over the long term. These observatories are regionally based and have specific initial scientific questions, monitoring strategies, databases, and modeling activities. The diversity of OZCAR-RI observatories and sites is well representative of the heterogeneity of the CZ and of the scientific communities studying it. Despite this diversity, all OZCAR-RI sites share a main overarching mandate, which is to monitor, understand, and predict ("earthcast") the fluxes of water and matter of the Earth's near surface and how they will change in response to the "new climatic regime." The vision for OZCAR strategic development aims at designing an open infrastructure, building a national CZ community able to share a systemic representation of the CZ , and educating a new generation of scientists more apt to tackle the wicked problem of the Anthropocene. OZCAR articulates around: (i) a set of common scientific questions and cross-cutting scientific activities using the wealth of OZCAR-RI observatories, (ii) an ambitious instrumental development program, and (iii) a better interaction between data and models to integrate the different time and spatial scales. Internationally, OZCAR-RI aims at strengthening the CZ community by providing a model of organization for pre-existing observatories and by offering CZ instrumented sites. OZCAR is one of two French mirrors of the European Strategy Forum on Research Infrastructure (eLTER-ESFRI) project