Arnaud Couairon

Bio: Arnaud Couairon is an academic researcher from École Polytechnique. The author has contributed to research in topics: Filamentation & Femtosecond. The author has an hindex of 56, co-authored 268 publications receiving 11742 citations. Previous affiliations of Arnaud Couairon include French Alternative Energies and Atomic Energy Commission & Centre national de la recherche scientifique.

Generation of intense, carrier-envelope phase-locked few-cycle laser pulses through filamentation

Abstract: Intense, well-controlled light pulses with only a few optical cycles start to play a crucial role in many fields of physics, such as attosecond science. We present an extremely simple and robust technique to generate such carrier-envelope offset (CEO) phase locked few-cycle pulses, relying on self-guiding of intense 43-fs, 0.84 mJ optical pulses during propagation in a transparent noble gas. We have demonstrated 5.7-fs, 0.38 mJ pulses with an excellent spatial beam profile and discuss the potential for much shorter pulses. Numerical simulations confirm that filamentation is the mechanism responsible for pulse shortening. The method is widely applicable and much less sensitive to experimental conditions such as beam alignment, input pulse duration or gas pressure as compared to gas-filled hollow fibers.

Femtosecond laser-induced damage and filamentary propagation in fused silica

Abstract: Bulk damage induced by fs IR laser pulses in silica is investigated both experimentally and numerically. In a strong focusing geometry, a first damage zone is followed by a narrow track with submicron width, indicating a filamentary propagation. The shape and size of the damage tracks are shown to correspond to the zone where the electron density created by optical field ionization and avalanche is close to ${10}^{20}\text{ }\text{ }{\mathrm{c}\mathrm{m}}^{\ensuremath{-}3}$. The relative role of avalanche and photoionization is studied. The plasma density produced in the wake of the pulse is shown to saturate around $2--4\ifmmode\times\else\texttimes\fi{}{10}^{20}\text{ }\text{ }{\mathrm{c}\mathrm{m}}^{\ensuremath{-}3}$.

Conical Forward THz Emission from Femtosecond-Laser-Beam Filamentation in Air

Abstract: We attribute a strong forward directed THz emission from femtosecond laser filaments in air to a transition-Cherenkov emission from the plasma space charge moving behind the ionization front at light velocity. Distant targets can be easily irradiated by this new source of THz radiation.

Filamentation and damage in fused silica induced by tightly focused femtosecond laser pulses

Abstract: We investigate experimentally and numerically the damage tracks induced by tightly focused $(\mathrm{NA}=0.5)$ infrared femtosecond laser pulses in the bulk of a fused silica sample. Two types of irreversible damage are observed. The first damage corresponds to a permanent change of refractive index without structural modifications (type I). It appears for input pulse energies beyond $0.1\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{J}$. It takes the form of a narrow track extending over more than $100\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{m}$ at higher input powers. It is attributed to a change of the polarizability of the medium, following a filamentary propagation which generates an electron-hole plasma through optical field ionization. A second type of damage occurs for input pulse energies beyond $0.3\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{J}$ (type II). It takes the form of a pear-shaped structural damage associated with an electron-ion plasma triggered by avalanche. The temporal evolution of plasma absorption is studied by pump-probe experiments. For type I damage, a fast electron-hole recombination is observed. Type II damage is linked with a longer absorption.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

Abstract: A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Principles Of Optics Electromagnetic Theory Of Propagation Interference And Diffraction Of Light

Abstract: Thank you for reading principles of optics electromagnetic theory of propagation interference and diffraction of light. As you may know, people have search hundreds times for their favorite novels like this principles of optics electromagnetic theory of propagation interference and diffraction of light, but end up in harmful downloads. Rather than enjoying a good book with a cup of coffee in the afternoon, instead they are facing with some infectious bugs inside their computer.

Mechanisms of pulsed laser ablation of biological tissues.

Abstract: Author(s): Vogel, Alfred; Venugopalan, Vasan | Abstract: The mechanisms of pulsed laser ablation of biological tissues were studied. The transiently empty space created between the fiber tip and the tissue surface improved the optical transmission to the target and thus increased the ablation efficiency. It was found that the structure and morphology also affect the energy transport among tissue constituents.

Attosecond Physics

Abstract: Summary form only given. Fundamental processes in atoms, molecules, as well as condensed matter are triggered or mediated by the motion of electrons inside or between atoms. Electronic dynamics on atomic length scales tends to unfold within tens to thousands of attoseconds (1 attosecond [as] = 10-18 s). Recent breakthroughs in laser science are now opening the door to watching and controlling these hitherto inaccessible microscopic dynamics. The key to accessing the attosecond time domain is the control of the electric field of (visible) light, which varies its strength and direction within less than a femtosecond (1 femtosecond = 1000 attoseconds). Atoms exposed to a few oscillations cycles of intense laser light are able to emit a single extreme ultraviolet (XUV) burst lasting less than one femtosecond. Full control of the evolution of the electromagnetic field in laser pulses comprising a few wave cycles have recently allowed the reproducible generation and measurement of isolated sub-femtosecond XUV pulses, demonstrating the control of microscopic processes (electron motion and photon emission) on an attosecond time scale. These tools have enabled us to visualize the oscillating electric field of visible light with an attosecond "oscilloscope", to control single-electron and probe multi-electron dynamics in atoms, molecules and solids. Recent experiments hold promise for the development of an attosecond X-ray source, which may pave the way towards 4D electron imaging with sub-atomic resolution in space and time.