Generation and characterisation of few-pulse attosecond pulse trains at 100 kHz repetition rate

Mikhail Osolodkov,Carmen S Menoni,Peter Šušnjar,Tobias Witting,Claus P Schulz,Federico J Furch,Fabio Cavalcante,Marc J J Vrakking,Felix Schell

doi:10.1088/1361-6455/aba77d

Abstract

The development of attosecond pump–probe experiments at high repetition rate requires the development of novel attosecond sources maintaining a sufficient number of photons per pulse. We use 7 fs, 800 nm pulses from a non-collinear optical parametric chirped pulse amplification laser system to generate few-pulse attosecond pulse trains (APTs) with a flux of >106 photons per shot in the extreme ultraviolet at a repetition rate of 100 kHz. The pulse trains have been fully characterised by recording frequency-resolved optical gating for complete reconstruction of attosecond bursts (FROG-CRAB) traces with a velocity map imaging spectrometer. For the pulse retrieval from the FROG-CRAB trace a new ensemble retrieval algorithm has been employed that enables the reconstruction of the shape of the APTs in the presence of carrier envelope phase fluctuations of the few-cycle laser system.

Highlights

High energy near infrared (NIR) pulses with durations on the femtosecond timescale allow the generation of attosecond pulses in the extreme ultraviolet (XUV) through the process of high-order harmonic generation (HHG) [1]
In this letter we report on the generation and characterisation of few-pulse XUV attosecond pulse trains (APTs) in the 15 to 40 eV energy range with a flux of >106 photons per shot at a repetition rate of 100 kHz
In order to extract the temporal profile of the fluctuating APTs and the short NIR pulses, we apply the time-domain ensemble extended ptychographic iterative engine that we have recently introduced and that is presented in our companion paper ‘retrieval of attosecond pulse ensembles from streaking experiments using mixed state time-domain ptychography’, which is part of the present special issue [20]

Summary

Introduction

High energy near infrared (NIR) pulses with durations on the femtosecond timescale allow the generation of attosecond pulses in the extreme ultraviolet (XUV) through the process of high-order harmonic generation (HHG) [1]. Combined with a phase-locked replica of the NIR pulses in a pump–probe configuration, attosecond XUV pulses can be used for attosecond timescale spectroscopy experiments [2]. A more sophisticated approach than the latter is the coincident detection of all charged particles resulting from the interaction utilizing reaction microscopes or COLTRIMS (cold target recoil ion momentum spectroscopy) detectors [3]. Measurements of the correlated three-dimensional momentum distributions of all charged particles resulting from the interaction in coincidence provides access to the photoelectron momentum distributions in the recoil frame in the case of a dissociating molecule. Applied to strong field ionization experiments [4, 5], the combination of attosecond pump–probe spectroscopy with coincidence detection [6] permitted spatio-temporal reconstruction of the photoionization process in a CO molecule [7], and has been used to characterise the influence of coupled electron–nuclear dynamics during the dissociative ionization of H2 molecules [8]

Methods

Results

Conclusion