1 Efficient high order harmonic generation using quasi phase matching Sameh DABOUSSI Journées...

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Efficient high order harmonic generation using quasi phase matching

Sameh DABOUSSI

Journées scientifiques de L'EDOM 7 et 8 mars 2011

2Presentation

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.


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100 mJ – 40 fs – 10 Hz HHG : > 10 nm - 10 Hz

High repetition rate X-ray laser

CPA Ti:Sa

Laser System :

800nm 10Hz 3 J

HHG beam line HHG beam line

XUV laser Beam line

LASERIX, a Facility with a Large combination of XUV sources : LASERIX, a Facility with a Large combination of XUV sources :


4Gas cell orcapillary

Intense fs laser 1014 W/cm2LensIris

High-order harmonics

X-ray filter

Soft X-ray spectrometer

HHG beam line at LASERIX: HHG beam line at LASERIX:


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Microscopic effect : Three-step model of the intense laser pulse interaction with atoms

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.

Principle of High-Order Harmonic Generation Principle of High-Order Harmonic Generation

2. Acceleration

3. Recombination

Laser field

Atomicpotential

1. Tunnelingelectron

Photon XUV

qEXUV= Ip + Ec


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Phase matching : Constructive addition of X-ray fieldsPhase matching : Constructive addition of X-ray fields

ktlcoh

)(

Laser fieldXUV emission

atmos

qq eE

Conversion efficiency: ~ 10-6 Science 280, 1412 (1998)

Destructive interference : lmed is an even multiple of lcoh

Constructive interference:

lmed is an odd multiple of lcoh

kkq Laserkq

0

Propagation in gaz medium


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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

Quasi Phase Matching HHG from Gas mediumQuasi Phase Matching HHG from Gas medium

No absorption limitsHigh ionisation

Higher HHG orders


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Methods to achieve Quasi Phase MatchingMethods 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.

M.Zepf PRL 99, 143901 (2007)

150 μm


9Harmonic order (q)

Experimental conditions :

Gaz cell : 8mmGaz : Néon E = 20 mJP= 20 mbar gaz cellλlaser= 800 nmPulse duration = 40 fs1 m foc length

High-Order Harmonic in gas cell at LASERIXHigh-Order Harmonic in gas cell at LASERIX

HHG characteristics :

•Harmonic order : 31 – 47•Wavelength : 17-27 nm•Energy per harmonic order : 10nJ•Pulse duration : 10fs


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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).


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Thanks for attention

[email protected]://laserix.u-psud.fr


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