%0 Journal Article %T Nonlinear beam shaper for femtosecond laser pulses, from Gaussian to flat-top profile %+ Laboratoire d'optique appliquée (LOA) %+ Laboratoire d'optique et biosciences (LOB) %A Mercier, Brigitte %A Rousseau, Jean-Philippe %A Jullien, A. %A Antonucci, Laura %< avec comité de lecture %@ 0030-4018 %J Optics Communications %I Elsevier %V 283 %N 14 %P 2900 %8 2010 %D 2010 %R 10.1016/j.optcom.2010.04.004Journal articles %X We present a straightforward method to transform a spatially Gaussian femtosecond laser beam into a flattop shaped beam. The proposed technique takes advantage of a nonlinear phase induced in positive Kerr medium followed by a simple optical system. The variation of the refractive index with the laser intensity creates a phase plate which induces changes in the beam profile after propagation; flat-top and doughnut profiles are observed. The shaping conditions are computed numerically and confirmed experimentally. The method does not introduce energy losses. The device is very simple, self-regulated, flexible and does not need a manufactured phase plate or precise alignment. This method can be useful for light-matter interaction and laser machining. Cop 2010 Elsevier B.V. All rights reserved. %G English %L hal-00805075 %U https://polytechnique.hal.science/hal-00805075 %~ X %~ ENSTA %~ CNRS %~ X-LOA %~ X-LOB %~ X-DEP %~ X-DEP-BIO %~ X-DEP-PHYS %~ PARISTECH %~ ENSTA_LOA