Spatially and spectrally resolved quantum path interference with chirped driving pulses

• Published in: New journal of physics Vol. 18; no. 12; pp. 123032 - 123048
• Main Authors: Carlström, Stefanos, Preclíková, Jana, Lorek, Eleonora, Larsen, Esben Witting, Heyl, Christoph M, Pale ek, David, Zigmantas, Donatas, Schafer, Kenneth J, Gaarde, Mette B, Mauritsson, Johan
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 23.12.2016
• Subjects: 42.65.Ky; 42.65.Re; Argon; Atom and Molecular Physics and Optics; Atom- och molekylfysik och optik (Här ingår: Kemisk fysik, kvantoptik); dipole phase parameters; Dipoles; Far fields; Fysik; high-order harmonic generation; Interference; Mathematical models; Natural Sciences; Naturvetenskap; Parameters; Physical Sciences; Physics; quantum path interference; Schrodinger equation; Spectra; Time dependence
• ISSN: 1367-2630; 1367-2630
• DOI: 10.1088/1367-2630/aa511f

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 ( s ) and long ( 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.