1. 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

2. 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

3. Acceleration results -
Stable ~ 230 MeV electron bunches
J. Osterhoff et al., PRL 101, (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%

4. 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

5. 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

6. 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)

7. 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)

8. 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

9. Basic concept and layout

10. 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

11. Basic concept and layout

12. 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 70 MHz
dazzler allows for phase correction and amplitude shaping
regenerative amplifier in 180 µJ (±1.8 µJ std.)
8-pass booster amplifier gives 300 mJ (±10 mJ std.)
after compression Hz, 66% efficiency
80 mJ in frequency-doubled beam
S. Klingebiel et al., Opt. Exp. 19, 5357 (2011)

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

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

15. 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

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

17. 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

18. Basic concept and layout

19. 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

20. 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!

21. 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: 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

22. 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

23. 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