Petawatt Field Synthesizer Towards Joule-scale few-cycle pulses – progress and challenges of short-pulse pumped OPCPA Zsuzsanna Major Laboratory for Attosecond and High-Field Physics Max-Planck-Institut für Quantenoptik Garching, Germany & Ludwig-Maximilians-Universität München, Garching Workshop on Petawatt-Lasers at Hard X-Ray Light Sources, Dresden-Rossendorf 7th September 2011

Laser-driven compact secondary sources Motivation Laser-driven compact secondary sources Laser-wakefield acceleration of electrons ATLAS laser laser focussing gas-cell target electron acceleration electron spectrometer transmitted laser beam diagnostics

Acceleration results - Stable ~ 230 MeV electron bunches J. Osterhoff et al., PRL 101, 085002 (2008) simple setup improved energy stability and repeatability electrons are accelerated on every single shot electron energies always very similar these electron bunches can be used for further applications for the first time Acceleration results - With discharge Without discharge Energies ~ 300 MeV ~ 150 MeV Energy fluctuations 30 % 2.5 % Energy spread > 5 % Charge in peak < 10 pC 10 ~ 20 pC Charge fluctuations 75 % 16 % Divergence 1.3 mrad RMS 0.9 mrad RMS Pointing stability 8 mrad RMS 1.4 mrad RMS Injection ~ 90 % 100%

Spontaneous undulator radiation M. Fuchs et al., Nature Phys. 5, 826 (2009) 200 MeV, 5 pC undulator: 30 cm, 5 mm period spectrum in 70% of all laser shots hints for normalized emittance of ~ 0.8 mm.mrad

Undulator radiation: outlook Few-cycle driver source: Applications: 5-keV table-top XFEL: scientific case: e.g. single molecule imaging femto-chemistry needs 1-2 PW-class lasers, 20 fs ok 25-keV XFEL needs ~10-20 PW lasers medical imaging ~ 5 fs Near-term applications of spontaneous undulator radiation: x-ray pump-probe experiments 5 keV, 5 fs possible with 0.1 PW lasers short electron bunch duration: fraction of the plasma wavelength no nonlinear laser pulse evolution before electron injection can occur

High-harmonic generation from solid surfaces Aim: attosecond pulse generation with high intensity Are all harmonics in phase: Attosecond pulse train? With few-cycle pulses: single attosecond pulse? G.D. Tsakiris et al., New Journal of Physics (2006)

Phase-stabilized few-cycle driver: single attosecond pulses Few-cycle driver source: 3J, 5 fs sin-pulse cos-pulse G.D. Tsakiris et al., New Journal of Physics (2006)

5 fs 3 J 10 Hz The Petawatt Field Synthesizer (PFS) at MPQ Max-Planck-Institut für Quantenoptik Ludwig-Maximilians Universität München The Petawatt Field Synthesizer (PFS) at MPQ 5 fs 3 J 10 Hz High bandwidth (OPCPA) Large crystals High – rep. pump Diode pumping Thin KDP or DKDP CPA High pump intensity ps pulse duration Yb:YAG CPA pump laser Large aperture DKDP OPCPA bulk/chirped mirror compression

Basic concept and layout

Frontend Ti:Sa oscillator Ti:Sa 10-pass (modified Femtopower CompactPro): up to 2 mJ, 60 nm, 1 kHz prism compressor: ~23 fs 20 μJ in the range of 700 – 1400 nm

Basic concept and layout

CPA pump laser chain 3.5 nm bandwidth by spectral shaping ~ 900 fs FWHM pulse duration after compression 2-stage fiber amplifiers pre-amplify to 1 W @ 70 MHz dazzler allows for phase correction and amplitude shaping regenerative amplifier in saturation @ 180 µJ (±1.8 µJ std.) 8-pass booster amplifier gives 300 mJ (±10 mJ std.) after compression 200 mJ @ 10 Hz, 66% efficiency 80 mJ in frequency-doubled beam S. Klingebiel et al., Opt. Exp. 19, 5357 (2011)

CPA pump laser chain Imaging multipass Next stage under development: H3 Imaging multipass >1 J achieved in simple H3 prototype:

Timing jitter between pump and seed total path difference ~ 400 m - max. jitter: ~ 100 fs = 30mm stabilization to 10-7 needed

Timing jitter between pump and seed superposition of slow (< 1 Hz), large amplitude drift and fast small amplitude fluctuations slow drift can be eliminated by active stabilization origin of the large fluctuations: air turbulences, pointing fluctuations especially in strecher-compressor setup Pump laser OPCPA seed BBO jitter analysis delay stage Active stabilization

Timing jitter between pump and seed pointing fluctuation at compressor (stretcher) input: S. Klingebiel et al., in preparation 16

S. Klingebiel et al., in preparation Timing jitter between pump and seed pointing fluctuation inside compressor (stretcher) due to air turbulence: S. Klingebiel et al., in preparation stretcher and compressor in vacuum 17

Basic concept and layout

Amplification in 2 OPA stages FFT of amplified spectrum: OPA Experiments Amplification in 2 OPA stages 1st stage LBO 4 mm Epump = 7 mJ Øpump = 3 mm (FWHM) Eseed = 20 µJ 2nd stage LBO 2 mm Epump = 50 mJ Øpump = 5 mm (FWHM) FFT of amplified spectrum: 19 Amplification dynamics has to be checked in detail in experiment and compared to design calculations

Comparison with “pseudo”-3D simulation in DKDP OPA experiments Comparison with “pseudo”-3D simulation in DKDP I. Ahmad, C. Skrobol et al., in preparation Saturation measurements Small signal gain measurements Excellent agreement between experiment and calculation, promising for scalability!

I. Ahmad, C. Skrobol et al., in preparation OPA design ”pseudo”-3D model including saturation, dispersion, walk-off, using experimental seed spectrum Total pump energy: 20 J @ 515 nm Comparison between different models 8 stages of DKDP 2.4 J output energy transform limited pulse duration: 5.6fs 2 stages of LBO + 3 stages of DKDP 3.7 J output energy transform limited pulse duration: 5.3fs I. Ahmad, C. Skrobol et al., in preparation

Summary On the route towards Joule-scale few-cycle pulse generation by short-pulse pumped OPCPA we have demonstrated the feasibility of the main building blocks: → generation of synchronized seed pulses → active stabilization of seed and pump pulse to ~ 100 fs → broadband amplification in DKDP and LBO → agreement between experiment and calculation Next stage of pumplaser under development: 4 × 1 J Next steps for OPA: → compression with material and chirped mirrors → verify inherently good contrast → demonstrate scalability

Thank you! PFS-team (MPQ) S. A. Trushin, I. Ahmad, C. Wandt, S. Klingebiel, C. Skrobol, M. Siebold*, J. A. Fülöp**, Zs. Major, F. Krausz, and S. Karsch *HZDR, Germany; ** University of Pécs, Hungary MPQ + LMU V. Pervak, A. Apolonski Universidad de Salamanca, Spain R. Borrego Varillas University of Szeged, Hungary M. Mero ICFO Barcelona, Spain A. Thai, P. K. Bates, J. Biegert Forsvarets Forskningsinstitutt, Kjeller, Norway G. Arisholm Friedrich-Schiller Universität, Jena, Germany J. Hein