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- Item27 W 2.1 µm OPCPA system for coherent soft X-ray generation operating at 10 kHz(Washington, DC : Soc., 2020) Feng, Tianli; Heilmann, Anke; Bock, Martin; Ehrentraut, Lutz; Witting, Tobias; Yu, Haohai; Stiel, Holger; Eisebitt, Stefan; Schnürer, MatthiasWe developed a high power optical parametric chirped-pulse amplification (OPCPA) system at 2.1 µm harnessing a 500 W Yb:YAG thin disk laser as the only pump and signal generation source. The OPCPA system operates at 10 kHz with a single pulse energy of up to 2.7 mJ and pulse duration of 30 fs. The maximum average output power of 27 W sets a new record for an OPCPA system in the 2 µm wavelength region. The soft X-ray continuum generated through high harmonic generation with this driver laser can extend to around 0.55 keV, thus covering the entire water window (284 eV - 543 eV). With a repetition rate still enabling pump-probe experiments on solid samples, the system can be used for many applications. © 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
- ItemSpatio-temporal characterisation of a 100 kHz 24 W sub-3-cycle NOPCPA laser system(Bristol : IOP Publ., 2018-02-26) Witting, Tobias; Furch, Federico J.; Vrakking, Marc J.J.In recent years, OPCPA and NOPCPA laser systems have shown the potential to supersede Ti:sapphire plus post-compression based laser systems to drive next generation attosecond light sources via direct amplification of few-cycle pulses to high pulse energies at high repetition rates. In this paper, we present a sub 3-cycle, 100 kHz, 24 W NOPA laser system and characterise its spatio-temporal properties using the SEA-F-SPIDER technique. Our results underline the importance of spatio-temporal diagnostics for these emerging laser systems.
- ItemRetrieval of attosecond pulse ensembles from streaking experiments using mixed state time-domain ptychography(Bristol : IOP Publ., 2020) Witting, Tobias; Furch, Federico J.; Kornilov, Oleg; Osolodkov, Mikhail; Schulz, Claus P.; Vrakking, Marc J.J.The electric field of attosecond laser pulses can be retrieved from laser-dressed photoionisation measurements, where electron wavepackets that result from single-photon ionisation by the attosecond pulse in the presence of a dressing field are produced. In case of fluctuating dressing laser and/or attosecond pulses, e.g. due to pulse-to-pulse fluctuations of the carrier envelope phase of the infrared laser pulse, commonly applied retrieval algorithms result in the erroneous extraction of the pulse fields. We present a mixed state time-domain ptychography algorithm for the retrieval of pulse ensembles from attosecond streaking experiments. © 2020 The Author(s). Published by IOP Publishing Ltd.
- ItemGeneration and characterisation of few-pulse attosecond pulse trains at 100 kHz repetition rate(Bristol : IOP Publ., 2020) Osolodkov, Mikhail; Furch, Federico J.; Schell, Felix; Šušnjar, Peter; Cavalcante, Fabio; Menoni, Carmen S.; Schulz, Claus P.; Witting, Tobias; Vrakking, Marc J.J.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. © 2020 The Author(s). Published by IOP Publishing Ltd.
- ItemIn situ temporal measurement of ultrashort laser pulses at full power during high-intensity laser–matter interactions(Washington, DC : OSA, 2020) Crespo, Helder M.; Witting, Tobias; Canhota, Miguel; Miranda, Miguel; Tisch, John W.GIn laser-matter interaction experiments, it is of paramount importance to characterize the laser pulse on target (in situ) and at full power. This allows pulse optimization and meaningful comparison with theory, and it can shed fundamental new light on pulse distortions occurring in or on the target.Here we introduce and demonstrate a new technique based on dispersion-scan using the concurrent third harmonic emission from the target that permits the full (amplitude and phase), in situ, in-parallel characterization of ultrashort laser pulses in a gas or solid target over a very wide intensity range encompassing the 1013-1015Wcm-2regime of high harmonic generation and other important strong-field phenomena, with possible extension to relativistic intensities presently inaccessible to other diagnostics. © 2020 OSA - The Optical Society. All rights reserved.
- ItemPhase cycling of extreme ultraviolet pulse sequences generated in rare gases([London] : IOP, 2020) Wituschek, Andreas; Kornilov, Oleg; Witting, Tobias; Maikowski, Laura; Stienkemeier, Frank; Vrakking, Marc J.J.; Bruder, LukasThe development of schemes for coherent nonlinear time-domain spectroscopy in the extreme-ultraviolet regime (XUV) has so far been impeded by experimental difficulties that arise at these short wavelengths. In this work we present a novel experimental approach, which facilitates the timing control and phase cycling of XUV pulse sequences produced by harmonic generation in rare gases. The method is demonstrated for the generation and high spectral resolution characterization of narrow-bandwidth harmonics (˜14 eV) in argon and krypton. Our technique simultaneously provides high phase stability and a pathway-selective detection scheme for nonlinear signals - both necessary prerequisites for all types of coherent nonlinear spectroscopy. © 2020 The Author(s). Published by IOP Publishing Ltd on behalf of the Institute of Physics and Deutsche Physikalische Gesellschaft.