Generation of ultra-intense single-cycle laser pulses by using photon deceleration

Abstract

A scheme to generate single-cycle laser pulses is presented based on photon deceleration in underdense plasmas. This robust and tunable process is ideally suited for lasers above critical power because it takes advantage of the relativistic self-focusing of these lasers and the nonlinear features of the plasma wake. The mechanism is demonstrated by particle-in-cell simulations in three and 2 1 ⁄2 dimensions, resulting in pulse shortening up to a factor of 4, thus making it feasible to generate few-femtosecond single-cycle pulses in the optical to IR domain with intensities I > 10 20 W͞cm 2 by using present-day laser technology.T he quest for attosecond laser pulses is at the forefront of research in laser physics (1-3). Pulses in the attosecond range may give rise to the development of attoelectronics, making it possible to study the dynamics and to control electronic processes in biology, chemistry, and solid-state physics, in the same way femtosecond laser technology led to femtochemistry (1). On the other hand, state-of-the art ultra-intense lasers can deliver up to 1 PW, with pulse durations from 500 fs down to 18 fs, at 800 nm to 1 m (4). Two paths toward attosecond pulses can be identified; the first one, associated with solid-state laser oscillator technology (5), has pushed the limit of the shortest laser pulse down to 4.5 fs in the near-IR to visible domain. At these wavelengths, breaking the attosecond threshold implies the generation of subcycle pulses (6, 7). The other path is based on the careful combination of some of the short wavelength harmonics generated in the ionization of a rare gas by intense femtosecond laser pulses (8), leading to 100-as extreme UV pulses (3). The possibility of producing even shorter single-cycle, ultra-intense pulses opens the way to new unexplored physics and the possibility of generating ultra-intense attosecond pulses (3).Current methods for ultra-short pulse generation and compression already push the limits of the linear and nonlinear optics of conventional materials (5). Further developments on ultraintense lasers must then be based on the nonlinear optics of plasmas (the medium capable of handling high-power densities and heat loads) at relativistic intensities (9). An example is, for instance, the plasma equivalent of the optical parametric amplifier (10), recently introduced by Shvets et al. (11).In this article, we propose a method to further shorten the existing shortest pulses to ultra-intense single-cycle pulses. This method is based on the frequency downshift (or photon deceleration) experienced by a laser pulse in a plasma because of the combined self-interaction with the relativistic mass nonlinearity and the laser wake field (12). The photon frequency downshift is accompanied by the conservation of the total wave action, leading to a strong enhancement of the laser field vector potential (13). Relativistic self-focusing also provides an additional amplification of the peak laser field. Using threedimensional (3D) and two-dimensional (2D) particle-in-cel...

One-to-One Full-Scale Simulations of Laser-Wakefield Acceleration Using QuickPIC

“…1-b) leading to an increase of the peak power of the pulse by nearly a factor of 2. In addition to selffocusing, this also resulted from longitudinal self-modulation effects [13]. As the laser is modulated and the transverse and longitudinal ponderomotive forces become stronger, electrons are progressively expelled from the axis, leading to nearly full electron cavitation at s ≈ 2 mm.…”

Spatiotemporal Evolution of Intense Short Gaussian Laser Pulses in Weakly Relativistic Magnetized Plasma

“…It was demonstrated numerically that high power microwave pulses can be compressed inside a magnetized plasma by changing the magnitude or the direction of the magnetic field [32]. Tsung et al proposed a method based on the frequency downshift (or photon deceleration) in underdense plasmas to generate single-cycle ultra-intense laser pulses [33]. In Ref.…”

Pulsed mid-infrared radiation from spectral broadening in laser wakefield simulations

“…At higher powers, the radial expulsion of electrons initially focuses the pulse and can result in a transient self-guiding structure: relativistic self-focusing and guiding [10][11][12][13][14] . Additionally, the local reduction in group velocity accompanying the red-shifting compresses the pulse [15][16][17][18] . Both nonlinear localization effects can enhance the ponderomotive force and consequently the electron density gradient.…”