Wednesday, October 9

8:00am-8:30am Registration

WE9: High average power ultrafast lasers

Session Chair: A. Fry, Stanford Linear Accelerator Center (United States)

WE9.1: Amplified programmable frequency-tunable fs pulse bursts: from THz synthesis to strong-field molecular applications

A. Pugžlys, Center for Physical Sciences & Technology (Lithuania);  T. Flöry, V. Stummer, E. Kaksis, I. Astrauskas, P. Malevich, TU Wien (Austria); A. Baltuška, TU Wien (Austria) and Center for Physical Sciences & Technology (Lithuania); G. Krizsán, G. Polónyi, J. Fülöp, University of Pécs and ELI-ALPS (Hungary)

We demonstrate fully controllable fs multimillijoule pulse bursts with the energy handling, throughput efficiency and frequency resolution substantially exceeding that achievable in spatial-light-modulator and interferometric techniques. Our phase-controlled pulse-burst amplification is based on differential pathlength stabilization between the master oscillator and the amplifier cavities. This technique boosts the safe level of extractable burst energy and suppresses fluctuations in various burst-mode applications. The demonstrated proof-of-concept experiments include coherent control of nitrogen-ion emission via multiple-pulse excitation and generation of tunable narrowband THz pulses via optical rectification.

High-Power Ultrafast Industrial Thin-Disk Lasers

C. Teisset, C. Grebing, C. Herkommer, S. Klingebiel, P. Kroetz, K. Michel, S. Prinz, C. Wandt, T. Metzger, TRUMPF Scientific Lasers (Germany)

TRUMPF Scientific Lasers manufactures customized ultrafast systems based on TRUMPF industrial thin-disk laser components. These laser sources combine ease of operation with robustness and tailored output specifications. In this contribution, we present different commercial ultrafast solutions based on regenerative amplifiers with up to 200 mJ of pulse energy and more than 1 kW of average power. In parallel, significant progress in thin-disk based multipass arrangements has led to multikilowatt average output powers. This paper will review the latest advancement in the development of a 1-J multipass thin-disk amplifier. In addition, concepts for nonlinear compression to reach pulse durations below 50 fs will be discussed.

Performance scaling of ultrafast two micron fiber CPA systems and high-power nonlinear pulse compression to the sub-2 cycle regime

M. Gebhardt, Friedrich-Schiller-University Jena (Germany) and Helmholtz-Institute Jena (Germany); C. Gaida, Friedrich-Schiller-University Jena (Germany); T. Heuermann, Friedrich-Schiller-University Jena (Germany) and Helmholtz-Institute Jena (Germany); Z. Wang, C. Jauregui, Friedrich-Schiller-University Jena (Germany); J. Antonio-Lopez, A. Schülzgen, R. Amezcua- Correa, CREOL, University of Central Florida (United States); J. Rothhardt, Helmholtz-Institute Jena (Germany) and Friedrich-Schiller- University Jena (Germany); J. Limpert, Friedrich-Schiller-University Jena (Germany) and Helmholtz-Institute Jena (Germany) and Fraunhofer Institute for Applied Optics and Precision Engineering (Germany)

High repetition rate sources of energetic, few-cycle pulses are useful tools for strong-field science and high-harmonic generation (HHG). Concerning HHG, a carrier wavelength beyond the well-explored near infrared spectral region is very attractive for increasing the phase-matched photon-energy cut-off. In particular, driving laser wavelengths spanning 1-2 μm make it possible to access the highly application relevant spectral region between 300 eV and 500 eV. In this contribution, we report on the current status and on the future prospects of ultrafast thulium-doped fiber laser systems operating around 1.9 μm wavelength. Average power scaling to 1 kW and peak power scaling to several GW is presented, together with the demonstration of 100 fs pulses emitted directly from a high energy fiber laser. Using a gas-filled, anti-resonant hollow-core fiber, nonlinear selfcompression of the pulses from a thulium-doped fiber CPA is investigated at 392 kHz repetition rate. We have achieved a record average power of 44 W, 5 GW of peak power and sub-two cycle pulse duration with a spectrum spanning 1.0-2.2 μm. Based on these results, we discuss future performance scaling and applications of the laser source.

Performance test results of ELI-ALPS SYLOS lasers

T. Stanislauskas, I. Balčiunas, Light Conversion Ltd (Lithuania); J. Adamonis, Ekspla (Lithuania); R. Budriūnas, G. Veitas, Light Conversion Ltd (Lithuania); D. Lengvinas, Ekspla (Lithuania); D. Gadonas, Light Conversion Ltd (Lithuania); S. Tóth, J. Csontos, Á. Börzsönyi, L. Tóth, T. Somoskői, K. Osvay, ELI-ALPS Ltd (Hungary)

We report on the recently delivered performance test results of ELI-ALPS Single Cycle Laser (SYLOS) lasers, which will be the drivers of three beamlines for attosecond pulse generation and one for electron acceleration. The current parameters of the main SYLOS laser system reached a peak power of 4.9 TW and 2.17-cycle (6.4 fs) pulses at 1 kHz repetition rate. The reliability was demonstrated with 12 hours long-term measurement periods for three consecutive days without substantial adjustments. Exceptional energy stability of 0.72%, CEP stability of 220 mrad and pointing stability of 0.4 μrad was recorded during these long-term runs. SYLOS will be sharing the load of the four beamlines with a smaller system called SYLOS Experiment Alignment laser, which has similar output parameters to SYLOS laser, except the 10 Hz repetition rate and without CEP-stability. The performance test results of this system is also reported.

10:00am-10:30am Coffee Break

WE10: Scientific Applications

Session Chair: M.-E. Couprie, Synchrotron SOLEIL (France)

Terahertz-induced Nonlinear Phonon Dynamics

M. E. Kozina, SLAC National Accelerator Lab (United States); M. Fechner, Max Planck Institute for the Structure and Dynamics of Matter (Germany); P. Marsik, Department of Physics, University of Fribourg (Switzerland); T. van Driel, J. M. Glownia, SLAC National Accelerator Lab (United States); C. Bernhard, Department of Physics (Switzerland); M. Radovic, Swiss Light Source, Paul Scherrer Institut (Switzerland); D. Zhu, SLAC National Accelerator Lab (United States); S. Bonetti, eDepartment of Molecular Sciences and Nanosystems, Università Ca’ Foscari Venezia (Italy) and Department of Physics, Stockholm University (Sweden); U. Staub, Swiss Light Source, Paul Scherrer Institut (Switzerland); M. Hoffmann, SLAC National Accelerator Lab (United States)

We report measurements of the structural response of a thin film of SrTiO3 (STO) under strong excitation with singlecycle terahertz (THz) fields using ultrafast x-rays. STO has a known soft phonon that is in close resonance with the central frequency of the THz driving field. For weak THz fields, we observe atomic motion which we associate with resonant phonon excitation. As we increase the THz field strength, we detect both a saturation in the soft mode excitation amplitude as well as the appearance of several new frequencies closely matched to known higher-frequency phonons in STO. Combining DFT calculations with measured x-ray diffraction measurements, we are also able to extract the soft mode phonon potential.

Table-top Coherent Diffractive Imaging using a Fiber Laser Driven High-order Harmonic Source

W. Eschen, G. Tadesse, R. Klas, Friedrich-Schiller-Universität, Institute of Applied Physics (Germany) and Helmholtz-Institute Jena (Germany); V. Hilbert, Friedrich-Schiller-Universität, Institute of Applied Physics (Germany) and Helmholtz- Institute (Germany); F. Tuitje, Friedrich-Schiller-Universität, Institute of Optics and Quantum Electronics (Germany); M. Steinert, D. Schelle, A. Nathanael, F. Schrempel, V. Schuster, Friedrich-Schiller-Universität, Institute of Applied Physics (Germany); M. Zürch, Fritz Haber Institute (Germany); T. Pertsch, H. Gross, Friedrich-Schiller-Universität, Institute of Applied Physics (Germany); C. Spielmann, Friedrich-Schiller-Universität, Institute of Optics and Quantum Electronics (Germany); A. Tünnermann, J. Limpert, Friedrich-Schiller-Universität, Institute of Applied Physics (Germany) and Helmholtz-Institute (Germany) and Fraunhofer Institute for Applied Optics and Precision Engineering (Germany); J. Rothhardt, Friedrich-Schiller-Universität, Institute of Applied Physics (Germany) and Helmholtz-Institute Jena (Germany)

Laser development in the recent years has pushed the coherent XUV flux of high-harmonic generation to values that are comparable to synchrotrons. This development enables Coherent Diffractive Imaging experiments on a lab scale that were before only possible at large scale facilities. In this contribution we present our latest results on table-top lensless XUV-Imaging. Achieving record-high resolutions using a high-order harmonic source at 18 nm with two different imaging modalities. Using the Fourier Transform Holography (FTH) method a record resolution of 23 nm was demonstrated. With the more general ptychographic method we were able to resolve features down to a size of 45 nm. Further, we show our recent advances towards imaging at the technological relevant wavelength of 13.5 nm which will in future enable actinic inspection of lithography masks.

Ultrafast single-cycle far-infrared pulses for imaging pump-probe dynamics on the atomic scale

V. Jelic, University of Alberta (Canada) and Michigan State University (USA); Y. Luo, P. H. Nguyen, J. A. M. Calzada, D. Mildenberger, Y.-J. Liu, F. A. Hegmann, University of Alberta (Canada)

Recent progress in THz-pulse-coupled scanning tunneling microscopy (THz-STM) has demonstrated that ultrafast single-cycle far-infrared transients can non-resonantly control electron tunneling at sub-nanometer length scales and sub-picosecond timescales. The THz pulse electric field couples to the atomically sharp tip of the STM, generating a spatially and temporally localized ultrafast tunnel current that can be used to explore the dynamics of atoms and molecules on surfaces. In the work presented here, hundreds of electrons are rectified across the tunnel junction per THz pulse, while imaging a photoexcited GaAs(110) surface with a spatial resolution of 3 Å and a temporal resolution of 500 fs. The STM topography image and ultrafast THz-STM image are acquired simultaneously as the tip is raster scanned across the sample surface.

Laser cooling of atoms with an optical frequency comb

D. Aumiler, N. Šantić, D. Buhin, D. Kovačić, I. Krešić, T. Ban, Institute of Physics (Croatia)

We report on laser cooling of neutral rubidium atoms by using a single mode of a frequency comb. Cooling is achieved on a dipole-allowed transition at 780 nm in a one-dimensional retro-reflected beam geometry. Temperatures are measured using standard time-of-flight imaging. We show the dependence of the temperature on the cooling time, intensity and detuning of the frequency comb. The lowest temperature achieved is approximately equal to the Doppler temperature and is limited by the intensity of the comb mode driving the cooling transition. Additionally, we verify the analogy between frequency comb and continuous-wave laser cooling. Our work is a step towards laser cooling of atoms with strong cycling transitions in the vacuum ultraviolet, such as hydrogen, deuterium and antihydrogen, where generation of continuous-wave laser light is limited by current laser technology. Achieving efficient cooling at these wavelengths would significantly improve the precision of optical frequency standards, enable measurements of fundamental constants with unprecedented accuracy, improve tests of charge, parity, and time reversal symmetry, and open the way to achieving quantum degeneracy width new atomic species.

The BELLA Center: Ultrahigh Intensity Laser Facility for Users to Study High Field Interactions in Laser-Plasma Science

C. Toth, K. Nakamura, A. J. Gonsalves, S. Steinke, J. Bin, H. Tsai, T. M. Ostermayr, C. G. Geddes, S. K. Barber, J. van Tilborg, T. Schenkel, C. B. Schroeder, E. H. Esarey, Lawrence Berkeley National Lab (United States)

The BELLA Center provides several CPA laser beamlines for the development and application of laser-plasma accelerators (LPAs), and enables multi-beam experimental opportunities combining photons and particles for users. Recent results include the production and characterization of electron beams at 0.01-8 GeV, and low-divergence ion beams at a few MeV. Femtosecond, keV-band betatron radiation is also generated from the acceleration process. Development of a source of femtosecond quasi-monoenergetic MeV Thomson photons is underway.

12:45pm-7:00pm Excursion