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Abstract

The thesis is devoted to the analytical and numerical studies of high-order harmonic generation and super-intense single attosecond pulse emission via ultra-relativistic laserplasma interaction. In the ultra-relativistic regime, the laser radiation pressure induces plasma ion motion through the so called hole-boring effect, resulting in frequency widening of the harmonic spectra. This widening, analyzed analytically and validated by particle-in-cell simulations, produces a quasi-continuous frequency spectrum, a prerequisite for generating an intense single attosecond pulse. Based on the results and physical considerations, parameter maps highlighting the optimum regions for generating a single intense attosecond pulse and coherent XUV radiation are presented. Moreover, a robust plasma gating is developed to generate a super-intense phase-stabilized single attosecond pulse. The hole-boring effect limits the most efficient high-frequency emission in one laser cycle making it possible to isolate a single attosecond pulse. The generated pulse is characterized by a stabilized spectral phase ψ(ω) ≈± π/2 and an ultra-broad exponential spectrum up to keV region bounded by ROM scaling and CSE scaling. The unprecedented intensity highlights the potential of the isolated attosecond pulse for performing attosecond-pump attosecond-probe experiments.