Parametric amplification of attosecond pulse trains at 11 nm

Abstract

We report the first experimental demonstration of the parametric amplification of attosecond pulse trains at around 11 nm. The helium amplifier is driven by intense laser pulses and seeded by high-order harmonics pulses generated in a neon gas jet. Our measurements suggest that amplification takes place only if the seed pulse-trains are perfectly synchronized in time with the driving laser field in the amplifier. Varying the delay, we estimate the durations of the individual extreme ultraviolet pulses within the train to be on the order of 0.2 fs. Our results demonstrate that strong-field parametric amplification can be a suitable tool to amplify weak attosecond pulses from non-destructive pump-probe experiments and it is an important step towards designing amplifiers for realization of energetic XUV pulses with sub-femtosecond duration using compact lasers fitting in university laboratories.

Avalanche of stimulated forward scattering in high harmonic generation

“…it was revealed that the amplification of coherent XUV attosecond pulses by strongfield induced stimulated forward scattering can be obtained by synchronizing a weak XUV pulse with a strong IR pulse. This theoretical prediction was soon corroborated by the experiments in Ref [25], which measured XUV attosecond pulse amplification in He gas at around 110 eV photon energies. Beyond independent theoretical [18] and experimental [25] demonstration, in the present work we show large agreement between theoretical and experimental observations concerning amplification by avalanche of a XUV attosecond pulse train in an He gas amplifier at the 110 eV region.…”

“…This theoretical prediction was soon corroborated by the experiments in Ref [25], which measured XUV attosecond pulse amplification in He gas at around 110 eV photon energies. Beyond independent theoretical [18] and experimental [25] demonstration, in the present work we show large agreement between theoretical and experimental observations concerning amplification by avalanche of a XUV attosecond pulse train in an He gas amplifier at the 110 eV region. The simulations show that the ionization potential of the gas [19] and the consequent dispersion caused by the free electrons in the amplifying medium are key factors to produce XUV amplification in a specific spectral region.…”

Intrapulse x-ray parametric amplification in high-order-harmonic generation

“…In particular, 26 we showed that forward scattering can be largely enhanced 27 when an XUV pulse is optimally synchronized with the IR 28 pulse [11]. This theoretical prediction was soon corroborated 29 by experiments [12] and a further detailed comparison between 30 the theory and the experimental measurements showed good 31 qualitative agreement [14]. Strong-field-mediated intrapulse x-32 ray parametric amplification (IXPA) processes were identified 33 in [14] as decisive for the amplification at the single-atom 34 level.…”

Quantum Path Interference and Multiple Electron Scattering in Soft X-Ray High-Order Harmonic Generation

“…If the conditions for X-ray parametric amplification were fulfilled, the harmonics were efficiently generated, and the quantum-path interference of two dominating trajectories provided the uncommon harmonic line structure. These results together with the examination of the temporal dynamics of the generation process [38] help us to better understand high-order harmonic generation and X-ray parametric amplification at high laser intensities, as well as providing guidelines to extend the generated spectrum to higher photon energies at increased efficiency or to realize efficient, ultrahigh repetition rate [39], high harmonic sources.…”