Laser-wakefield acceleration offers the promise of a compact electron accelerator for generating a multi-GeV electron beam using the huge field gradient induced by an intense laser pulse, compared to conventional rf accelerators. However, the energy and quality of the electron beam from the laser-wakefield accelerator have been limited by the power of the driving laser pulses and interaction properties in the target medium. Recent progress in laser technology has resulted in the realization of a petawatt (PW) femtosecond laser, which offers new capabilities for research on laser-wakefield acceleration. Here, we present a significant increase in laser-driven electron energy to the multi-GeV level by utilizing a 30-fs, 1-PW laser system. In particular, a dual-stage laser-wakefield acceleration scheme (injector and accelerator scheme) was applied to boost electron energies to over 3 GeV with a single PW laser pulse. Three-dimensional particle-in-cell simulations corroborate the multi-GeV electron generation from the dual-stage laser-wakefield accelerator driven by PW laser pulses.

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Nanostructured thin plastic foils have been used to enhance the mechanism of laser-driven proton beam acceleration. In particular, the presence of a monolayer of polystyrene nanospheres on the target front side has drastically enhanced the absorption of the incident 100 TW laser beam, leading to a consequent increase in the maximum proton energy and beam charge. The cutoff energy increased by about 60% for the optimal spheres' diameter of 535 nm in comparison to the planar foil. The total number of protons with energies higher than 1 MeV was increased approximately 5 times. To our knowledge this is the first experimental demonstration of such advanced target geometry. Experimental results are interpreted and discussed by means of 2(1/2)-dimensional particle-in-cell simulations.

High-intensity lasers are critical for the exploration of strong field quantum electrodynamics. We report here a demonstration of laser intensity exceeding 1 0 23 W / c m 2 with the CoReLS petawatt (PW) laser. After wavefront correction and tight focusing with a two-stage adaptive optical system and an f/1.1 ( f = 300 m m ) off-axis parabolic mirror, we obtained near diffraction-limited focusing with a spot size of 1.1 µm (FWHM). From the measurement of 80 consecutive laser shots at 0.1 Hz, we achieved a peak intensity of ( 1.1 ± 0.2 ) × 1 0 23 W / c m 2 , verifying the applicability of the ultrahigh intensity PW laser for ultrahigh intensity laser–matter interactions. From the statistical analysis of the PW laser shots, we identified that the intensity fluctuation originated from air turbulence in the laser beam path and beam pointing. Our achievement could accelerate the study of strong field quantum electrodynamics by enabling exploration of nonlinear Compton scattering and Breit–Wheeler pair production.

We demonstrated the generation of 4.2 PW laser pulses at 0.1 Hz from a chirped-pulse amplification Ti:sapphire laser. The cross-polarized wave generation and the optical parametric chirped-pulse amplification stages were installed for the prevention of the gain narrowing and for the compensation of the spectral narrowing in the amplifiers, obtaining the spectral width of amplified laser pulses of 84 nm (FWHM), and enhancing the temporal contrast. The amplified laser pulses of 112 J after the final booster amplifier were compressed to the pulses with 83 J at 19.4 fs with a shot-to-shot energy stability of 1.5% (RMS). This 4.2 PW laser will be a workhorse for exploring high field science.