Showing papers by "Gerard Mourou published in 2013"

The future is fibre accelerators

Abstract: Could massive arrays of thousands of fibre lasers be the driving force behind next-generation particle accelerators? The International Coherent Amplification Network project believes so and is currently performing a feasibility study.

Amplification of ultrashort laser pulses by brillouin backscattering in plasmas.

Abstract: Plasma media, by exciting Raman (electron) or Brillouin (ion) waves, have been used to transfer energy from moderately long, high-energy light pulses to short ones. Using multidimensional kinetic simulations, we define here the optimum window in which a Brillouin scheme can be exploited for amplification and compression of short laser pulses over short distances to very high power. We also show that shaping the plasma allows for increasing the efficiency of the process while minimizing other unwanted plasma processes. Moreover, we show that, contrary to what was traditionally thought (i.e., using Brillouin in gases for nanosecond pulse compression), this scheme is able to amplify pulses of extremely short duration.

Probing Nonperturbative QED with Optimally Focused Laser Pulses

Abstract: We study nonperturbative pair production in intense, focused laser fields called e-dipole pulses. We address the conditions required, such as the quality of the vacuum, for reaching high intensities without initiating beam-depleting cascades, the number of pairs which can be created, and experimental detection of the created pairs. We find that e-dipole pulses offer an optimal method of investigating nonperturbative QED.

Spectral characteristics of ultra-short laser pulses in plasma amplifiers

Abstract: Amplification of laser pulses based on the backscattering process in plasmas can be performed using either the response of an electron plasma wave or an ion-acoustic wave. However, if the pulse durations become very short and the natural spread in frequency a substantial amount of the frequency itself, the Raman and Brillouin processes start to mix. Kinetic simulations show the transition from a pure amplification regime, in this case strong-coupling Brillouin, to a regime where a considerable downshift of the frequency of the amplified pulse takes place. It is conjectured that in the case of very short pulses, multi-modes are excited which contribute to the amplification process.

Sub-surface terahertz imaging through uneven surfaces: visualizing Neolithic wall paintings in Çatalhöyük

Abstract: Pulsed terahertz imaging is being developed as a technique to image obscured mural paintings. Due to significant advances in terahertz technology, portable systems are now capable of operating in unregulated environments and this has prompted their use on archaeological excavations. August 2011 saw the first use of pulsed terahertz imaging at the archaeological site of Catalhoyuk, Turkey, where mural paintings dating from the Neolithic period are continuously being uncovered by archaeologists. In these particular paintings the paint is applied onto an uneven surface, and then covered by an equally uneven surface. Traditional terahertz data analysis has proven unsuccessful at sub-surface imaging of these paintings due to the effect of these uneven surfaces. For the first time, an image processing technique is presented, based around Gaussian beam-mode coupling, which enables the visualization of the obscured painting.

Terahertz analysis of stratified wall plaster at buildings of cultural importance across Europe

Abstract: Terahertz (THz) radiation is being developed as a tool for the analysis of cultural heritage, and due to recent advances in technology is now available commercially in systems which can be deployed for field analysis. The radiation is capable of penetrating up to one centimetre of wall plaster and is delivered in ultrafast pulses which are reflected from layers within this region. The technique is non-contact, non-invasive and non-destructive. While sub-surface radar is able to penetrate over a metre of wall plaster, producing details of internal structures, infrared and ultraviolet techniques produce information about the surface layers of wall plaster. THz radiation is able to provide information about the interim region of up to approximately one centimetre into the wall surface. Data from Chartres Cathedral, France, Riga Dome Cathedral, Latvia, and Chartreuse du Val de Benediction, France is presented each with different research questions. The presence of sub-surface paint layers was expected from documentary evidence, dating to the 13th Century, at Chartres Cathedral. In contrast, at the Riga Dome Cathedral surface painting had been obscured as recently as 1941 during the Russian occupation of Latvia using white lead-based paint. In the 13th Century, wall paintings at the Chapel of the Frescos, Chartreuse du Val de Benediction in Villeneuve les Avignon were constructed using sinopia under-painting on plaster covering uneven stonework.. This paper compares and contrasts the ability of THz radiation to provide information about sub-surface features in churches and Cathedrals across Europe by analysing depth based profiles gained from the reflected signal.

Electron acceleration and emission in a field of a plane and converging dipole wave of relativistic amplitudes with the radiation reaction force taken into account

Abstract: A comparative analysis is performed of the electron emission characteristics as the electrons move in laser fields with ultra-relativistic intensity and different configurations corresponding to a plane or tightly focused wave. For a plane travelling wave, analytical expressions are derived for the emission characteristics, and it is shown that the angular distribution of the radiation intensity changes qualitatively even when the wave intensity is much less than that in the case of the radiation-dominated regime. An important conclusion is drawn that the electrons in a travelling wave tend to synchronised motion under the radiation reaction force. The characteristic features of the motion of electrons are found in a converging dipole wave, associated with the curvature of the phase front and nonuniformity of the field distribution. The values of the maximum achievable longitudinal momenta of electrons accelerated to the centre, as well as their distribution function are determined. The existence of quasi-periodic trajectories near the focal region of the dipole wave is shown, and the characteristics of the emission of both accelerated and oscillating electrons are analysed.

HFiTT - Higgs Factory in Tevatron Tunnel

Abstract: This paper proposes a Higgs factory located in the Tevatron tunnel. It is based on a photon collider by using a recirculating e- linac and fiber laser technology.

Angular emission and polarization dependence of harmonics from laser–solid interactions

Abstract: Laser plasma interaction experiments have been performed to characterize high order harmonic emission up to the 18th order using high rep rate mJ level laser pulses at relativistic intensities. The experiments were compared to two- and three-dimensional particle-in-cell simulations. The harmonic divergence was found to be less than 4° (full-width at half-maximum) at highest intensity and increased as the laser was defocused (i.e. as the intensity was reduced). The polarization dependence on the harmonic generation efficiency and divergence was also measured. Circular polarization was found to cause a deflection in the angle of emission of the harmonics—an effect which may be beneficial in the use of such harmonics for efficient isolated attosecond pulse production.

Kinetic simulations of intense light pulses generated by Brillouin backscattering in laser-plasma interaction

Abstract: Due to their extremely high damage threshold, plasmas can sustain much higher light intensities than conventional solid state optical materials. Because of this, lately much attention has been devoted to the possibility of using parametric instabilities in plasmas to generate very intense light pulses in a low-cost way. Although short-pulse amplification based on the Raman approach has been successful and goes back a long time, it is shown that using Brillouin in the so called strong-coupling regime (sc-SBS) has several advantages and is very well suited to amplify and compress laser seed pulses on short distances to very high intensities. We present here recent multi-dimensional kinetic simulations that show the feasibility of achieving amplified light pulses of up to 10 18 W/cm 2 . Contrary to what was traditionally thought, this scheme is able to amplify pulses of extremely short duration. Although seed amplification via sc-SBS has already been shown experimentally, these results suggest further experimental exploration, in order to improve the energy transfer.

ICAN: The Next Laser Powerhouse

Abstract: An international team of researchers is looking toward the next frontier of high-energy laser physics: building efficient, high–average-power lasers. With a revolutionary architecture that combines thousands of coherent fibers, the laser being developed under the ICAN project could transform nuclear medicine, detect nuclear waste and form the basis for the next great particle accelerator.

Image retrieval techniques for THz applications in cultural heritage

Abstract: Techniques to retrieve reliable images from complicated objects are described, overcoming problems introduced by uneven surfaces, giving enhanced depth resolution and improving image contrast The techniques are illustrated with application to THz imaging of concealed wall paintings

Arrangement for generating a proton beam and an installation for transmutation of nuclear wastes

Abstract: The invention relates to an arrangement for producing a proton beam. This arrangement is characterized in that it is constituted by a laser driven accelerator of protons adapted to produce a beam of relativistic protons of 0.5 GeV to 1 GeV with a current in the order of tens of mA, such as a current of 20 mA. The invention can be used for transmutating nuclear waste.

Free-Electron Laser driven by fibre based laser feeding a Laser Plasma Accelerator

Abstract: The invention concerns a Free Electron Laser - FEL - EUV or soft X-ray light source comprising: a fibre-based laser (1), comprising a plurality of amplifying fibres wherein an initial seed laser pulse is distributed and amplified, and means for grouping together the elementary pulses amplified in the said fibre in order to form a single amplified global laser pulse (3); a laser plasma accelerator - LPA - (6) based on Laser Wake-Field Acceleration (LWFA) in the bubble regime wherein the said global laser pulse (3) generates relativistic electron beams (10), a beam focusing system (12) transporting electron beams (10) from the laser plasma accelerator (6), an undulator (13) wherein relativistic electron beams (10) generate an electromagnetic beam, and a beam separator system, wherein the said electron beam and the said electromagnetic beam are separated.

Highly scalable coherent fiber combining using interferometric technique

Abstract: We demonstrate the scalability of fiber phase locking system using interferometric method. The system allows complete phase error map measurement with a /60 rms accuracy in a single acquisition of only 6 pixels per fiber.

Method for the production of ultrashort and ultrahigh peak power laser pulses and system for putting into practice this method

Abstract: The invention concerns a method for producing ultrashort and ultrahigh peak power laser pulses and a system for putting into practice this method. The production of ultrashort and ultrahigh peak power laser pulses is implemented by amplifying and compressing relatively long and low energy laser pulses to such ultra short and ultrahigh peak power pulses, and the use of the plasma compression technique for producing ultrashort and ultrahigh peak power pulses having a duration in the range of 20 femtoseconds (fs) or less and an energy of at least 10 Kilojoule (kJ), wherein a pump pulse (PP) in the order of picoseconds (ps) and a seed pulse (SS) are applied to the plasma cell (PLC), which are synchronized with one another and adapted to the plasma cell.