Attosecond lighthouses from plasma mirrors

Wheeler, Jonathan; Borot, Antonin; Monchocé, S.; Vincenti, Henri; Ricci, A.; Malvache, Arnaud; López-Martens, Rodrigo; Quéré, F.

doi:10.1038/nphoton.2012.284

Cited by 196 publications

(103 citation statements)

References 26 publications

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“…Due to these remarkable properties, plasma mirrors are now largely used in ultrafast optics as a single-shot high-intensity optical device, e.g. to improve temporal contrast of femtosecond pulses [24], for the tight focusing of ultraintense beams [26], or for the generation of high-order harmonics and attosecond pulses [27,28].…”

Section: Plasma Mirrors As Electron Injectorsmentioning

confidence: 99%

Vacuum laser acceleration of relativistic electrons using plasma mirror injectors

et al. 2015

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Accelerating particles to relativistic energies over very short distances using lasers has been a long standing goal in physics. Among the various schemes proposed for electrons, vacuum laser acceleration has attracted considerable interest and has been extensively studied theoretically because of its appealing simplicity: electrons interact with an intense laser field in vacuum and can be continuously accelerated, provided they remain at a given phase of the field until they escape the laser beam. But demonstrating this effect experimentally has proved extremely challenging, as it imposes stringent requirements on the conditions of injection of electrons in the laser field. Here, we solve this long-standing experimental problem for the first time by using a plasma mirror to inject electrons in an ultraintense laser field, and obtain clear evidence of vacuum laser acceleration.With the advent of PetaWatt class lasers, this scheme could provide a competitive source of very high charge (nC) and ultrashort relativistic electron beams.1 arXiv:1511.05936v1 [physics.plasm-ph] 18 Nov 2015Femtosecond lasers currently achieve light intensities at focus that far exceed 10 18 W/cm 2 at near infrared wavelengths [1]. One of the great prospects of these extreme intensities is the laser-driven acceleration of electrons to relativistic energies within very short distances.At present, the most advanced scheme consists of using ultraintense laser pulses to excite large amplitude wakefields in underdense plasmas, providing extremely high accelerating gradients in the order of 100 GV/m [2]. However, over the past decades, the direct acceleration of electrons by light in vacuum has also attracted considerable interest and has been extensively studied theoretically [3][4][5][6][7][8][9][10][11]. These investigations have been driven by the fundamental interest of this most elementary interaction, and by its potential for extreme electron acceleration through electric fields of > 10's TV/m that ultraintense laser pulses provide.The underlying idea is to inject free electrons into an ultraintense laser field so that they always remain within a given half optical cycle of the field, where they constantly gain energy until they leave the focal volume. 1D Analytical calculations [3] show that for relativistic electrons, the maximum energy gain from this process is ∆E ∝ mc 2 γ 0 a 2 0 , where γ 0 is the electron initial Lorentz factor, and a 0 is the normalized laser vector potential, m the electron mass, and c the vacuum light velocity. Reaching high energy gains thus requires high initial energies γ 0 1 and/or ultrahigh laser amplitudes (a 0 1).In contrast with the large body of theoretical work published on this vacuum laser acceleration (VLA) of electrons to relativistic energies, experimental observations have largely remained elusive [12][13][14][15][16][17] -sometimes even controversial [18,19]-and have so far not demonstrated significant energy gains. This is because VLA occurs efficiently only for electrons injected in t...

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Section: Plasma Mirrors As Electron Injectorsmentioning

confidence: 99%

Vacuum laser acceleration of relativistic electrons using plasma mirror injectors

et al. 2015

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“…38.Ph Over the past 30 years, solid-density plasmas driven by intense femtosecond (fs) pulses, so-called plasma mirrors, have been successfully tested as a source of high-order harmonics and attosecond XUV pulses in a number of experiments [1][2][3][4][5][6][7][8][9][10], where the laser intensity typically exceeds a few 10 14 W/cm 2 . Other experiments have shown it is also possible to accelerate energetic electrons from plasma mirrors for intensities above 10 16 W/cm 2 [11][12][13]. Attempting to understand each of these experimental observations invariably points to the key role played by the plasma-vacuum interface during the interaction both on the nanoscale spatially and on the sub-laser-cycle scale temporally [14,15].…”

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Anticorrelated Emission of High Harmonics and Fast Electron Beams From Plasma Mirrors

et al. 2016

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We report for the first time on the anticorrelated emission of high-order harmonics and energetic electron beams from a solid-density plasma with a sharp vacuum interface−plasma mirror−driven by an intense ultrashort laser pulse. We highlight the key role played by the nanoscale structure of the plasma surface during the interaction by measuring the spatial and spectral properties of harmonics and electron beams emitted by a plasma mirror. We show that the nanoscale behavior of the plasma mirror can be controlled by tuning the scale length of the electronic density gradient, which is measured in-situ using spatial-domain interferometry.PACS numbers: 52.38. Kd,52.38.Ph Over the past 30 years, solid-density plasmas driven by intense femtosecond (fs) pulses, so-called plasma mirrors, have been successfully tested as a source of high-order harmonics and attosecond XUV pulses in a number of experiments [1][2][3][4][5][6][7][8][9][10], where the laser intensity typically exceeds a few 10 14 W/cm 2 . Other experiments have shown it is also possible to accelerate energetic electrons from plasma mirrors for intensities above 10 16 W/cm 2 [11-13]. Attempting to understand each of these experimental observations invariably points to the key role played by the plasma-vacuum interface during the interaction both on the nanoscale spatially and on the sub-laser-cycle scale temporally [14,15].It is commonly assumed that the electronic density at the plasma mirror surface decreases exponentially from solid to vacuum over a distance L g , also called density gradient. When the laser pulse reflects on this plasma mirror, for every oscillation of the laser field, some electrons are driven towards vacuum and sent back to the plasma [16,17]. These bunches of so-called Brunel electrons [18] impulsively excite collective high-frequency plasma oscillations in the density gradient that lead to the emission of XUV radiation through linear mode conversion [19]. As illustrated in Fig 1(a), each position x of the plasma behaves as a nanoscale oscillator of frequency ω p (x) = ω 0 n e (x)/n c where ω 0 is the driving laser angular frequency, n e the local electronic density at position x and n c the critical density. This periodic mechanism, called Coherent Wake Emission (CWE), leads to efficient high harmonics generation for very short plasma scale lengths, typically L g ∼ λ/100 [19], even for subrelativistic intensities, a 0 < 1, where a 0 = eA 0 /mc is the normalized vector potential, e and m the electron charge and mass and c the speed of light. However, the efficiency significantly drops for L g >> λ/20

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“…5b) and observed a transition from a modulated harmonic-like spectrum, typically associated to a train of co-propagating attosecond pulses, into a continuous spectrum, characteristic of an isolated attosecond pulse. This is the first demonstration of single attosecond pulse generation from plasma mirrors driven at near-relativistic intensity [15].…”

Section: -P4mentioning

confidence: 82%