Ultrafast laser micro-nano structuring of transparent materials with high aspect ratio

Ultrafast lasers are ideal tools to process transparent materials because they spatially confine the deposition of laser energy within the material's bulk via nonlinear photoionization processes. Nonlinear propagation and filamentation were initially regarded as deleterious effects. But in the last decade, they turned out to be benefits to control energy deposition over long distances. These effects create very high aspect ratio structures which have found a number of important applications, particularly for glass separation with non-ablative techniques. This chapter reviews the developments of in-volume ultrafast laser processing of transparent materials. We discuss the basic physics of the processes, characterization means, filamentation of Gaussian and Bessel beams and provide an overview of present applications

Curved meshing for high Reynolds flows solved using high order framework

In this work, we are interested in the mesh generation problem for simulation of compressible fluids using high order schemes. For this kind of simulation, it is well-known [1] that the subparametric discretization used for geometry’s representation (usually piecewise-linear) may lead to errors dominating errors related to the variable field discretization. To solve this problem, we need to generate curved meshes with the same order of the numerical schemes. That means curved elements are essential for approximations of order more than three. As the mesh curvature is a non local property, an element cannot be curved without controlling the neighboring ones. Our strategy to generate curved meshes [2] is the following: we start with an initial straight mesh and we consider it as an elastic solid. We impose a displacement on the mesh boundaries in order to fit them with the curved geometry. Then we solve linear elasticity equations in order to propagate the boundary curvature inside the mesh. The validity of the final curved volumic mesh is obtained thanks to linear elasticity equation and some properties of Bezier curves/surfaces. We applied this algorithm to the generation of several simplicial curved meshes both in 2D and 3D. In particular, we are able to generate curved meshes for several turbulent test cases such a M6 wing (Figure 1) and a RAE airfoil. To illustrate the work, we performed some isogeometric numerical results for compressible fluid dynamics and we compared them with the results provided by the same scheme on a piecewise-linear mesh

Soliton beam propagation; space-time behaviour and spectral features

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Propagation soliton et auto-confinement de faisceaux laser par non linearité optique de kerr

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Enregistrement et selection de mode d'une fibre optique par spectroscopie optique coh�rente

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Laser beam self-splitting into solitons by optical Kerr nonlinearity

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Observation and applications of frequency modulations in single mode fibers

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Experimental observation of beams’ self-deflection appearing with two-dimensional spatial soliton propagation in bulk Kerr material

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Spatial-soliton-induced guided waves in a homogeneous nonlinear Kerr medium

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New method for precise characterisation of multimode optical fibres

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