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

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.