| 1. |
- Carlström, Stefanos, et al.
(författare)
-
Spatially and spectrally resolved quantum path interference with chirped driving pulses
- 2016
-
Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 18:12
-
Tidskriftsartikel (refereegranskat)abstract
- We measure spectrally and spatially resolved high-order harmonics generated in argon using chirped multi-cycle laser pulses. Using a stable, high-repetition rate laser we observe detailed interference structures in the far-field. The structures are of two kinds; off-axis interference from the long trajectory only and on-axis interference including the short and long trajectories. The former is readily visible in the far-field spectrum, modulating both the spectral and spatial profile. To access the latter, we vary the chirp of the fundamental, imparting different phases on the different trajectories, thereby changing their relative phase. Using this method together with an analytical model, we are able to explain the on-axis behaviour and access the dipole phase parameters for the short (${\alpha }_{{\rm{s}}}$) and long (${\alpha }_{{\rm{l}}}$) trajectories. The extracted results compare very well with phase parameters calculated by solving the time-dependent Schrödinger equation. Going beyond the analytical model, we are also able to successfully reproduce the off-axis interference structure.
|
|
| 2. |
- Larsen, Esben Witting, et al.
(författare)
-
Sub-cycle ionization dynamics revealed by trajectory resolved, elliptically-driven high-order harmonic generation
- 2016
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- The sub-cycle dynamics of electrons driven by strong laser fields is central to the emerging field of attosecond science. We demonstrate how the dynamics can be probed through high-order harmonic generation, where different trajectories leading to the same harmonic order are initiated at different times, thereby probing different field strengths. We find large differences between the trajectories with respect to both their sensitivity to driving field ellipticity and resonant enhancement. To accurately describe the ellipticity dependence of the long trajectory harmonics we must include a sub-cycle change of the initial velocity distribution of the electron and its excursion time. The resonant enhancement is observed only for the long trajectory contribution of a particular harmonic when a window resonance in argon, which is off-resonant in the field-free case, is shifted into resonance due to a large dynamic Stark shift.
|
|
