Rapid advancements in high-energy ultrafast lasers and free electron lasers have made it possible to obtain extreme physical conditions in the laboratory, which lays the foundation for investigating the interaction between light and matter and probing ultrafast dynamic processes. High temporal resolution is a prerequisite for realizing the value of these large-scale facilities. Here, we propose a new method that has the potential to enable the various subsystems of large scientific facilities to work together well, and the measurement accuracy and synchronization precision of timing jitter are greatly improved by combining a balanced optical cross-correlator (BOC) with near-field interferometry technology. Initially, we compressed a 0.8 ps laser pulse to 95 fs, which not only improved the measurement accuracy by 3.6 times but also increased the BOC synchronization precision from 8.3 fs root-mean-square (RMS) to 1.12 fs RMS. Subsequently, we successfully compensated the phase drift between the laser pulses to 189 as RMS by using the BOC for pre-correction and near-field interferometry technology for fine compensation. This method realizes the measurement and correction of the timing jitter of ps-level lasers with as-level accuracy, and has the potential to promote ultrafast dynamics detection and pump–probe experiments.

The paper is directed to the study of high-temperature plasma and ablation plasma formation as well as efficiency of the laser energy transfer to solid targets irradiated by laser pulses with intensities of 1–50 PW/cm2 and duration of 200–300 ps, i.e., at conditions corresponding to the characteristics of the laser spike designed to generate the igniting shock wave in the shock ignition concept. The experiments have been performed at Prague Asterix Laser System. The iodine laser delivered 250 ps (full width at half maximum) pulses with the energy in the range of 100–600 J at the first (λ1 = 1.315 µm) and third (λ3 = 0.438 µm) harmonic frequencies. The focal spot radius of the laser beam on the surface of Al or Cu targets made was gradually decreased from 160 to 40 µm. The diagnostic data collected using three-frame interferometry, X-ray spectroscopy, and crater replica technique were interpreted by two-dimensional numerical and analytical modeling which included generation and transport of fast electrons. The coupling parameter Iλ2 was varied in the range of 1 × 1014−8 × 1016 Wμm2/cm2 covering the regimes of weak to intense fast electron generation. The dominant contribution of fast electron energy transfer into the ablation process and shock wave generation was found when using the first harmonic laser radiation, the focal spot radius of 40–100 µm, and the laser energy of 300–600 J.