In this paper, we report the recent progress on the $1~\text{PW}/0.1~\text{Hz}$ laser beamline of Shanghai Superintense Ultrafast Laser Facility (SULF). The SULF-1 PW laser beamline is based on the double chirped pulse amplification (CPA) scheme, which can generate laser pulses of 50.8 J at 0.1 Hz after the final amplifier; the shot-to-shot energy fluctuation of the amplified pulse is as low as 1.2% (std). After compression, the pulse duration of 29.6 fs is achieved, which can support a maximal peak power of 1 PW. The contrast ratio at $-80~\text{ps}$ before main pulse is measured to be $2.5\times 10^{-11}$ . The focused peak intensity is improved by optimizing the angular dispersion in the grating compressor. The maximal focused peak intensity can reach $2.7\times 10^{19}~\text{W}/\text{cm}^{2}$ even with an $f/26.5$ off-axis parabolic mirror. The horizontal and vertical angular pointing fluctuations in 1 h are measured to be 1.89 and $2.45~\unicode[STIX]{x03BC}\text{rad}$ , respectively. The moderate repetition rate and the good stability are desirable characteristics for laser–matter interactions. The SULF-1 PW laser beamline is now in the phase of commissioning, and preliminary experiments of particle acceleration and secondary radiation under 300–400 TW/0.1 Hz laser condition have been implemented. The progress on the experiments and the daily stable operation of the laser demonstrate the availability of the SULF-1 PW beamline.

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An optical parametric chirped pulse amplifier (OPCPA) based on a large-aperture DKDP crystal and pumped by a 10 kJ level Nd:glass laser can serve as the final amplifier for a 100 PW level laser. A comprehensive numerical investigation on such a high-energy OPCPA is presented in this work. The effects on the efficiency–bandwidth product induced by the deuteration level, absorption loss, temperature variation, and optimization of zero-phase-mismatch wavelength (ZPMW) are analyzed in detail. Based on the analysis above, a three-dimensional numerical simulation taking into account the effects of pumping depletion, diffraction, and walk-off shows that, by optimization of ZPMW, broadband (over 210 nm spectral width in FWHM) and high efficiency ( > 37 % ) amplification can be realized in the DKDP crystal even with a moderate deuteration level of 70%, which can relax the requirement of a high deuteration level in a large-aperture DKDP crystal. The numerical analysis can provide meaningful guidance for the design and construction of 100 PW class laser systems.

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We report the dispersion management based on mismatched-grating compressor for a 100 PW level laser, which utilizes optical parametric chirped pulse amplification and meanwhile features large chirped pulse duration and ultra-broadband spectrum. The numerical calculation indicates that the amplified pulses with 4 ns chirped pulse duration and 210 nm spectral bandwidth can be directly compressed to sub-13 fs, which is close to the Fourier-transform-limit (FTL). More importantly, the tolerances of mismatched-grating compressor to the misalignment of stretcher, the error of desired grating groove density, and the variation of material dispersion are comprehensively analyzed, which is crucial important for its practical application. The results demonstrate that good tolerances and near FTL compressed pulses can be achieved simultaneously, just by keeping a balance between the residual second-, third-and fourth-order dispersion in the laser system. This work can offer a meaningful guideline for the design and construction of 100 PW level lasers.

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An all-optical approach to edge-enhanced proton radiography is realized by using a relativistic vortex laser irradiating on nanometer-thick foil. In the proof-of-principle experiments, the hollow proton beam was successfully produced by the transparent target normal electric field sheath in the break-out after-burner acceleration mechanism, using a superintense Laguerre–Gauss laser with the highest intensity of the laser exceeded 1020 W/cm2. An insect was imaged with the proton beam; the leg structures on the edge were clearly captured. By contrast, the dot proton source produced by a Gaussian laser was almost completely blocked by the insect's body, losing most edge information. Hollow-structured proton beams driven by vortex lasers conquer the dot imaging limit for high-energy proton beams, which may benefit imaging of capsule implosions in inertial confined fusion, instability research on expanding plasma, and precise positioning in medical therapy.

In this paper, we report that the conversion efficiency and spectrum of femtosecond optical parametric amplification (fs-OPA) can be significantly enhanced by employing a compact cascaded femtosecond OPA (CF-OPA) scheme with the self-compensation of the temporal walk-off between two nonlinear gain media. Correspondingly, the gain related temporal contrast can also be improved. The feasibility of the CF-OPA method using three cascaded BBO crystals is numerically and experimentally analyzed. Moreover, by replacing the conventional fs-OPA with the CF-OPA and optimizing the design, the performance of a nonlinear temporal filter combining cross-polarized wave generation and fs-OPA is comprehensively improved. The experimental results demonstrate the superiority of the CF-OPA scheme, which can generate high-performance cleaned pulses at 1 kHz repetition rate with energy of 340μJ, energy fluctuation below 0.9% (RMS), spectral width of 97 nm (FWHM), Fourier-transform-limited pulse width of 12 fs and temporal contrast better than 10−12. To the best of our knowledge, this is the first reported temporal walk-off self-compensated quasi-collinear CF-OPA geometry adopting three cascaded BBO crystals, which can be easily generalized to other wavelengths or nonlinear crystals. The above nonlinear temporal filter with a CF-OPA scheme has the rarest comprehensive parameters, which can provide excellent seed pulses for PW and 10 PW class femtosecond laser systems.