1. Efficient high order harmonic generation using quasi phase matching
Sameh DABOUSSI
Journées scientifiques de L'EDOM 7 et 8 mars 2011

2. Journées scientifiques de L'EDOM 7 et 8 mars 2011
Presentation
Sameh DABOUSSI, PhD Student at :
LPGP : Laboratoire de Physique des Gaz et des Plasmas : Gilles MAYNARD.
ITFIP : Interaction et Transport de Faisceaux Intenses dans les Plasmas : Brigitte CROS.
I started my thesis in January 2010 !
Co-supervisors: Sophie KAZAMIAS and Brigitte CROS .
LASERIX :
A facility of the University Paris Sud 11 attached to the research federation LUMAT (Lumière-Matière).
Director : David ROS
Located In Bat P, ENSTA-Palaiseau.
Team
Staff /Assistant professor : Sophie KAZAMIAS, Olivier GUILBAUD, Kevin CASSOU.
Laser engineer : Moana PITTMAN.
Electronics engineer : Olivier NEVEU.
Aim:
Optimisation of a high order harmonic generation source using quasi-phase matching method.
Journées scientifiques de L'EDOM 7 et 8 mars 2011

3. CPA Ti:Sa Laser System : 800nm 10Hz 3 J
LASERIX, a Facility with a Large combination of XUV sources :
CPA Ti:Sa
Laser System :
800nm 10Hz 3 J
HHG : > 10 nm - 10 Hz
100 mJ – 40 fs – 10 Hz
High repetition rate X-ray laser
HHG beam line
XUV laser Beam line
Journées scientifiques de L'EDOM 7 et 8 mars 2011

4. Journées scientifiques de L'EDOM 7 et 8 mars 2011
HHG beam line at LASERIX:
Gas cell or
capillary
Intense fs laser
 1014 W/cm2
Lens
Iris
High-order harmonics
X-ray filter
Soft X-ray
spectrometer
Journées scientifiques de L'EDOM 7 et 8 mars 2011

5. Journées scientifiques de L'EDOM 7 et 8 mars 2011
Principle of High-Order Harmonic Generation
Microscopic effect : Three-step model of the intense laser pulse interaction with atoms
3. Recombination
Laser
field
Photon XUV
1- Strong electric field distorts Coulomb potential of atom.
2- Acceleration of free electron by the electric field :
gained kinetic energy.
3- Recombination : high energy photon emission.
2. Acceleration
Atomic
potential
electron
1. Tunneling
qEXUV= Ip + Ec
Journées scientifiques de L'EDOM 7 et 8 mars 2011

6. Journées scientifiques de L'EDOM 7 et 8 mars 2011
Phase matching : Constructive addition of X-ray fields
Propagation in gaz medium
XUV emission
Laser field
Constructive interference:
lmed is an odd multiple of lcoh
Destructive interference :
lmed is an even multiple of lcoh
Conversion efficiency: ~ 10-6
Science 280, 1412 (1998)
Journées scientifiques de L'EDOM 7 et 8 mars 2011

7. Journées scientifiques de L'EDOM 7 et 8 mars 2011
Quasi Phase Matching HHG from Gas medium
No absorption limits
High ionisation
Higher HHG orders
Conversion efficiency >10-6 Science 302, 95 (2003)
- Suppress the emissions from the out-of-phase range.
- The HHG can add constructively and their amplitude increase
Journées scientifiques de L'EDOM 7 et 8 mars 2011

8. Journées scientifiques de L'EDOM 7 et 8 mars 2011
Methods to achieve Quasi Phase Matching
QPM via Pressure modulations.
QPM via intensity modulations:
Method 1:
Modulation of the inner diameter of the capillary
Method 2:
Fundamental and higher order mode beating in a gas filled capillary tube (Adopted method) !
Expected Results :
Conversion efficiency >10-6
Brightness ~1021 photons s-1mm-2mrad-2.
150 μm
M.Zepf PRL 99, (2007)
Journées scientifiques de L'EDOM 7 et 8 mars 2011

9. Journées scientifiques de L'EDOM 7 et 8 mars 2011
High-Order Harmonic in gas cell at LASERIX
Harmonic order (q)
Experimental conditions :
Gaz cell : 8mm
Gaz : Néon
E = 20 mJ
P= 20 mbar gaz cell
λlaser= 800 nm
Pulse duration = 40 fs
1 m foc length
HHG characteristics :
Harmonic order : 31 – 47
Wavelength : nm
Energy per harmonic order : 10nJ
Pulse duration : 10fs
Journées scientifiques de L'EDOM 7 et 8 mars 2011

10. Journées scientifiques de L'EDOM 7 et 8 mars 2011
Conclusions :
- The new high harmonic line is implemented at LASERIX
-I performed numerical simulations using a 1D code of harmonic generation in a cell : Controversy about the new method of high harmonic generation called “XPA” (X-ray parametric amplification)
S. Kazamias, S. Daboussi, O. Guilbaud, K. Cassou, C. Montet, O. Neveu, D. Ros, B. Cros and G. Maynard, Nature Physics 6, 926 (2010).
Prospects :
- Optimisation of a high-order harmonic source in order to achieve a high energy, reliable and efficient HHG source.
- Generation of high order harmonic in Argon and Neon in Capillary tubes with QPM : experiments at LASERIX and comparison to simulation results (LPGP code).
Journées scientifiques de L'EDOM 7 et 8 mars 2011

11. Journées scientifiques de L'EDOM 7 et 8 mars 2011
Thanks for attention
Journées scientifiques de L'EDOM 7 et 8 mars 2011