Versatile and robust reconstruction of extreme-ultraviolet pulses down to the attosecond regime

Abstract

A reliable and complete temporal characterization of ultrashort pulses is a crucial requisite for the correct interpretation of time-resolved experiments. This task is particularly challenging in the extreme-ultraviolet (XUV) spectral region, where usually different approaches are employed depending on the exact temporal structure of the pulses. Here we propose and validate against both simulated and experimental data a novel approach for the reconstruction of ultrashort XUV pulses produced by high-order harmonic generation in gases for three different conditions: isolated attosecond pulses, attosecond pulse trains, and few-femtosecond pulses obtained by spectral selection of single harmonics. The core of the method, named simplified trace reconstruction in the perturbative regime (STRIPE), is a novel mathematical description providing a simplified picture of the two-color photoionization process. This new approach is capable of accurately retrieving the temporal characteristics of the XUV pulses with notably reduced computational costs compared to other currently used reconstruction techniques. Direct comparison to standard approaches proves it to be superior in terms of flexibility, reliability, and robustness against noise and acquisition artifacts, making STRIPE a promising tool for pulse characterization.

Absolute delay calibration by analytical fitting of attosecond streaking measurements

“…This expression is in the form of a generic blind FROG spectrogram, which can be reconstructed with multiple iterative algorithms (e.g. PCGPA, LSGPA, ePIE, STRIPE) that have been devised on this analogy [20][21][22][23][24][25]. Over time, these methods became standard tools for characterizing attosecond pulses [10], at least when the XUV bandwidth is not exceedingly broad [26] and when experimental non-idealities can be neglected [27,28].…”

“…This allows assuming a reasonable multi-Gaussian model with a large enough number of free parameters. Alternatively, it is possible to reconstruct the attosecond streaking trace with another method [19][20][21][22][23][24][25] and use the retrieved XUV profile to determine the number of pulses. We regard both approaches to be equally valid.…”