http://loa.ensta.fr/ UMR 7639

Ultrahigh intensity lasers: physics and applications

Jérôme FAURE Laboratoire d’Optique Appliquée

What is laser intensity I (W/cm2) ?

2w0

!"

High intensity femtosecond lasers

Example: E=1 J, w0=20 !m, !0=30 fs (1 fs= 10-15 s) I0=5"1018 W/cm2

Nonlinear phenomena ultrafast phenomena

2 m

Salle Jaune Laser

Tunnel ionization

Bound electrons Nonlinear optics

Free electrons Laser-plasma interaction

Free electrons relativistic laser-plasma interaction

•  !"#$%&'()*()"+,#&)-#".)/&'/+0+1(0)+"'(0)2)+(.)/'"+&*2#.)+"'(0)3)

a0=0.1 a0=2

Illustration: the ponderomotive force on 1 electron

F ~ -dIlaser

F!

Champ E!

Laser vg ~ c

4  5'(.#&'6'17#)8'&$#)/9,:#,)#"#$%&'(,;)

4  <()+)/"+,6+;)$&#+%#,)+)=+>#-#".)

The ponderomotive force in a plasma

Plasma wakefields

Extreme accelerating fields: 100 GV/m instead of 10 MV/m

Ez

Er

Electron density Pulse

Use laser-plasma interaction for making particle accelerators

accelerating

focusing

Relativistic nonlinear optics: self-focusing

Nonlinear refraction index

Relativistic nonlinearity

#(r)"

<a2>

The plasma can « guide » light

What can we do with relativistic laser-plasma interactions ?

Fundamental questions: understand laser-plasma interaction, energy transfert from the laser to the plasma, nonlinear effects ! towards a control of these phenomena

Advanced light/particle sources: Produce particule and radiation sources with novel properties: femtosecond electron bunches and femtosecond X-rays, high energy, compact Electrons, ions, X-rays, high harmonics…

Applications of these new light sources: imaging of dense matter medical applications (radiotherapy) Femtosecond probing of condensed matter

Plasmas: very high electric fields ! Reduce the size of accelerators

Why plasmas: because LHC is so big !!!

The plasma wakefield as an accelerating cavity

Cavité RF: 1 m Onde plasma: 100 !m

Ez = 10-100 MV/m Ez = 10-100 GV/m

The laser pulse

the wave (accelerating structure)

The electrons

The physics is comparable to this

Gas jet

laser

electrons

Experimental principle

Injection beam 130 mJ, 30 fs $fwhm=28" 23 !m I ~ 4"1017 W/cm2

Pump beam 670 mJ, 30 fs, $fwhm=21"18 !m I ~ 4"1018 W/cm2

What it looks like in reality

Statistics (30 shots):

E = 206 +/- 11 MeV

charge = 13+/- 4 pC

%E = 14 +/- 3 MeV

%E/E = 6%

3 mm gas jet

J. Faure et al, Nature 431, 541 (2004) J. Faure et al, Nature 444, 737 (2006)

Stable and tunable monoenergetic beams

C. Rechatin et al, Phys. Rev. Lett 102, 164801 (2009) C. Rechatin et al, Phys. Rev. Lett. 103, 194804 (2009)

O. Lundh et al., Nat. Phys. 2011

108 electrons in 1.5 fs rms bunch !!

Femtosecond electron bunches

X-rays produced by relativistic electrons

β!

β!.!

Electron !

mm plasma wigglers

Equipe A. Rousse et K. Ta Phuoc (LOA)

synchrotrons free electron lasers

Use plasma cavities as a compact undulator

Why plasmas: because LCLS is so big !!!

A. Rousse, K. Ta Phuoc et al, Phys. Rev. Lett. 2004

20 mrad

E > 3 keV

Characteristics of the source: - 105 photons/shot/0.1% BW @ 1 keV!- divergence: 10’s mrad!- Duration: 10’s fs!- Spectrum: 1-10 keV!- Source size: 1- 2 microns!

Perspectives:!- Increase radiation energy by controlling electron trajectories!- Use PW lasers!

Radiation produced in a laser wakefield accelerator

Betatron radiation: fs X-ray source

Characteristics of the source: - 105 photons/shot/0.1% BW @ 1 keV!- divergence: 10’s mrad!- Duration: 10’s fs!- Spectrum: 10-1000 keV!- Source size: 1- 2 microns!

Perspectives:!- Produce a tunable and monochromatic source!- Use PW lasers!

Radiation produced at the collision between a laser pulse and a relativistic electron

Brevet publié 2012!

Compton scattering fs X-ray source

Pump-probe experiments on solids:

sonde

solide

#t

pompe

VUV – XUV photons: Photoemission* Electronic structure bands, gaps…

X-rays (keV) or electrons (100 keV): Diffraction: crystal structure Atomic motion

?

Femtoarpes Lab, Luca Perfetti (X), Marino Marsi (Orsay)

A motivation for these advanced sources: Ultrafast dynamics in out-of-equilibrium condensed matter

A motivation for these advanced sources: Ultrafast dynamics in out-of-equilibrium condensed matter

•  Creation of strongly out of equilibrium states of matter •  Dynamics of relaxation mechanisms: transfert of electronic

energy to the lattice, electron-phonon coupling •  But also new information on static physics through temporal

discrimination

•  Dynamics of photo-induced phase transitions •  Controlling phase transition with light ? •  Examples: solid-liquid transition; insulator metal transition; structural

transitions

Ex: 1T-TaS2 Eichberger et al., Nature 468, 799 (2010)

Electron diffraction on 1T-TaS2, Eichberger et al., Nature 2010

State of the art – current limitations

Use plasmas to produce 10 fs electron bunches for diffraction ?

fs X-ray and electron sources

!"#$%&'#((&()(*+#,-&)$.(#.&

?@;)ABA@C)D+/+(;)@EBAEC)F#&6+(G;)HI!A)JKLMNO)

P)MLL)8,C)$':#&#(%)ML)>#Q)HR&+G,)

"+&0#)S)#3/#(,*7#;)"*6*%#.)+$$#,,)

/)+#$'$.+&()(*+#,-&012#$*3,-)

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B'6/+$%)Y)"+&0#).*Z&+$1'()#[$*#($G)

P)\LL)8,)#"#$%&'()X9($:#,C)ML\RML])#^X9($:C)MLL)>#Q)

The perspectives and challenges of advanced light/particle sources

-  Demonstration experiments have been performed (it works) Femtosecond bunches, high energy, compact -  Physics is highly nonlinear: complex and hard to control

-  Make these sources truly useful and explore new physics -  Project FEMTOELEC (J. FAURE, LOA):

-  develop kHz, MeV electron bunches with < 10 fs for electron diffraction applications

-  Develop a middle energy plasma accelerator (100 MeV – 1 GeV) and X-ray sources (V. Malka, LOA, K. Ta Phuoc LOA)

- Increase electron energy: 10’s of GeV in a small laboratory staging of plasma accelerators: APPOLON project (PW laser) (A. Specka, LLR, LULI team)

27

Accelerating ions is also possible

J. Fuchs (LULI, X) A. Flacco (LOA, ENSTA-X) T. Ceccoti (SPAM, CEA Saclay)

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@'"*.)%+&0#%)J0"+,,C)6#%+"O)

!"#$%#&'())*)&

F#(#&+1'()'8)+()%&+*())'8)+c',#$'(.))/9",#,C)'(#)/#&)$G$"#)

?"%&+R:*0:)"*0:%)*(%#(,*%G)& E"6',%)$'6/"#%#)*'(*2+1'())& B&#+1'()'8)+),'"*.).#(,*%G)/"+,6+)& )!"#$%&#%'()%*+,-%(./0"-%%

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#"#$%&*$)-#".)

Attosecond pulse generation from plasma mirrors

F. Quéré (SPAM, CEA) R. Lopez-Martens (LOA, X)

High intensity laser plasma interaction in France (not exhaustive)

LOA, ENSTA-Polytechnique: electron acceleration (V. Malka, J. Faure, C. Thaury) ion acceleration (A. Flacco) X-ray generation (K. Taphuoc, A. Rousse) attosecond high-harmonic generation (R. Lopez-Martens) X-ray lasers (S. Sebban) LULI, Polytechnique: ion acceleration (J. Fuchs) fast-ignition (S. Baton) SPAM at CEA-SACLAY High-harmonics (B. Carré’s team, F. Quéré) Ion acceleration, electron acceleration (T. Cecotti, P. Martin’s team)

High intensity laser plasma interaction in France (not exhaustive)

LLR, Polytechnique Electron acceleration (A. Specka) LPGP, Orsay Electron acceleration (B. Cros) CELIA, Bordeaux X-ray sources for probing warm dense matter (F. Dorchies) High harmonic generation (E. Constant’s team) Fast ignition for inertial fusion (J. Santos, D. Batani, V. Tikhonchuk)