Palaiseau - FRANCE
Spatio-Temporal Chirped Pulse Amplification
for Avoiding Spectral Modifications in UltraShort Petawatt Lasers
C. Radier1,2, F. Giambruno1,3, C. Simon-Boisson2, V. Moro2, G. Chériaux1
1 LOA,
Chemin de la Hunière, 91761 Palaiseau Cedex, France
2 TOSA-DSL, 2 Avenue Gay Lussac, 78995 Elancourt, France
3 ILE, CNRS, Ecole Polytechnique, ENSTA, Institut d’optique, 91761 Palaiseau Cedex, France
christophe.radier@fr.thalesgroup.com
Context (1/2)
• Generation of multi-tens of joules energy and several tens
of femtoseconds duration pulses leading to petawatt peak
power levels
• Extremely high peak power pulses (10 PW) :
=> Vulcan laser 300 J / 30 fs (OPCPA) in LBO and KDP
=> Apollon-10P 150 J / 15 fs (CPA) in Ti:Sa
• Management of the spectral energy distribution in terms
of shape and bandwidth during their amplification process :
=> Temporal profile adapted to the high intensity
interaction
http://loa.ensta.fr/
UMR 7639
Context (2/2)
• OPCPA configuration in LBO / BBO / KDP :
Control of the spectrum (width and shape) by the angles in
the non-linear crystal and by the pump (temporal profile
and intensity)
• CPA configuration in Ti:Sa :
Amplification of temporally chirped pulses
=> Gain narrowing (inhomogeneous spectral gain )
2,40
0,90
Normalized spectral gain (u.a.)
Normalized spectral intensity (u.a.)
1,00
0,80
0,70
0,60
0,50
0,40
0,30
0,20
0,10
0,00
650
700
750
800
850
Wavelength (nm )
900
950
Input : Δλ½ = 85 nm
2,20
Pass 6 : Δλ½ = 62 nm
2,00
1,80
1,60
1,40
1,20
650
700
750
800
850
900
950
Wavelength (nm )
Frantz et Nodvik model : « Gain regime : J0(t) ~ Jsat / 1000 & G = 100 »
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UMR 7639
Context (2/2)
• OPCPA configuration in LBO / BBO / KDP :
Control of the spectrum (width and shape) by the angles in
the non-linear crystal and by the pump (temporal profile
and intensity)
• CPA configuration in Ti:Sa :
Amplification of temporally chirped pulses
= Gain shifting (amplification saturation )
0,90
Normalized spectral gain (u.a.)
Normalized spectral intensity (u.a.)
1,00
0,80
0,70
0,60
0,50
0,40
0,30
0,20
0,10
0,00
650
700
750
800
850
Wavelength (nm )
900
950
1,90
Input : λc = 794 nm
1,70
Pass 6 : λc = 808 nm
1,50
1,30
1,10
0,90
-1500
-1000
-500
0
500
1000
1500
Duration (ps)
Wavelength
(nm )
Frantz et Nodvik model : « Saturation regime : J0(t) ~ Jsat / G = 1,8 »
http://loa.ensta.fr/
UMR 7639
Existing solutions
• Different relevant active and passive solutions to
overcome the gain narrowing issue (mJ-level pulses in the
10 fs regime)
Acousto-optic programmable dispersive filter1
Multilayer Gain Narrowing compensators2,3,4
Negatively and Positively Chirped Pulsed Amplification5
• No solution to suppress the spectral shape modifications
due to saturation effects at moderate or high level energy
(> 1J).
1.
2.
3.
4.
5.
F. Verluise et al., “Amplitude and phase control of ultrashort pulses by use of an acousto-optic programmable dispersive filter: pulse compression and shaping”, Opt. Lett.
25, 575–577 (2000).
A. Amani Eilanlou et al., “Direct amplification of terawatt sub-10-fs pulses in a CPA system of Ti:sapphire laser,” Opt. Express 16, 13431–13438 (2008).
H. Takada, et al., “High-repetition-rate 12fs pulse amplification by a Ti:sapphire regenerative amplifier system,” Opt. Lett. 31, 1145–1147 (2006).
L. Antonucci, et al., “14 fs high temporal quality injector for ultra-high intensity laser,” Opt. Commun. 282, 1374–1379 (2009).
M. P. Kalashnikov et al., “Suppression of gain narrowing in multi-TW lasers with negatively and positively chirped pulse amplification,” Appl. Phys. B 81, 1059 (2005).
http://loa.ensta.fr/
UMR 7639
Spatio-Temporal Chirped Pulse Amplification
(STCPA) (1/2)
• Principle :
Combination of temporal and spatial dispersion
enable amplified spectra to be unaffected by saturation
effect.
i.e. spatially spreading spectral components to separately
amplify them and thus deleting the gain competition
http://loa.ensta.fr/
UMR 7639
Spatio-Temporal Chirped Pulse Amplification
(STCPA) (1/2)
• Principle :
Combination of temporal and spatial dispersion
enable amplified spectra to be unaffected by saturation
effect.
Ti:Sa Crystal
Pump Beam
IR Beam
Classical CPA scheme
Oscillator
http://loa.ensta.fr/
Stretcher
Power amplifier
Compressor
UMR 7639
Spatio-Temporal Chirped Pulse Amplification
(STCPA) (1/2)
• Principle :
Combination of temporal and spatial dispersion
enable amplified spectra to be unaffected by saturation
effect.
Ti:Sa Crystal
Pump Beam
IR Beam
STCPA scheme
Oscillator
Spatial spreading
Stretcher
Spatial compression
Power amplifier
Compressor
Gain zone shape adaptation
http://loa.ensta.fr/
UMR 7639
Spatio-Temporal Chirped Pulse Amplification
(STCPA) (2/2)
• Advantages :
No spectral shifting while preserving energy extraction in
saturation regime i.e. saturation effect is equally distributed
on all the spectral range instead of only the infrared edge.
• Conditions :
Input pulse has to be collimated
Spatial spreading law has to be inverse of that of spatial
compression
Pump beam has to be matched to the oblong seeded beam
• Inconvenient :
Gain narrowing not avoided in this configuration
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UMR 7639
Experiment Set Up
Frequency doubled
Nd:YVO4
3,7 W
Ti:Sa Oscillator
3,8 nJ / 80 MHz
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UMR 7639
Experiment Set Up
Frequency doubled
Nd:YVO4
3,7 W
Öffner triplet Stretcher
250 ps
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Ti:Sa Oscillator
3,8 nJ / 80 MHz
UMR 7639
Experiment Set Up
Frequency doubled
Nd:YVO4
1,5 mJ
1 kHz
3,7 W
Regenerative Amplifier
7,1 mJ / 1 kHz
Öffner triplet Stretcher
250 ps
Ti:Sa Oscillator
3,8 nJ / 80 MHz
Q-switched Nd:YLF
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UMR 7639
Experiment Set Up
Frequency doubled
Nd:YVO4
500 µJ
1 kHz
+ Birefringent Plate
3,7 W
Regenerative Amplifier
7,1 mJ / 1 kHz
Öffner triplet Stretcher
250 ps
Ti:Sa Oscillator
3,8 nJ / 80 MHz
Q-switched Nd:YLF
http://loa.ensta.fr/
UMR 7639
Experiment Set Up
Cylindric lenses
180 mJ / 10 Hz
LaK8
Prisms
Nd:YAG
Multipass amplifier
6 passes
Ti:Sa Absorption : 90%
Ø = 15 mm
Output
40 µJ
10 Hz
Pockels Cell
+ Birefringent Plate
500 µJ
1 kHz
Regenerative Amplifier
7,1 mJ / 1 kHz
Frequency doubled
Nd:YVO4
3,7 W
Öffner triplet Stretcher
250 ps
Ti:Sa Oscillator
3,8 nJ / 80 MHz
Q-switched Nd:YLF
http://loa.ensta.fr/
UMR 7639
Experiment Set Up
Cylindric lenses
180 mJ / 10 Hz
LaK8
Prisms
Output
40 µJ
10 Hz
Multipass amplifier
6 passes
Ti:Sa Absorption : 90%
Ø = 15 mm
IR Beam Before Prisms
Øx,y,FWHM = 1900 µm
Nd:YAG
IR Beam After Prisms
Øx,FWHM = 3000 µm
Øy,FWHM = 1900 µm
Aspect Ratio of 1,6
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UMR 7639
Experiment Set Up
Cylindric lenses
180 mJ / 10 Hz
LaK8
Prisms
Output
40 µJ
10 Hz
Nd:YAG
Multipass amplifier
6 passes
Ti:Sa Absorption : 90%
Ø = 15 mm
IR Beam After Prisms
Wavelength
spreading
19 nm/mm
Øx,FWHM = 3000 µm
Øy,FWHM = 1900 µm
http://loa.ensta.fr/
UMR 7639
Experiment Set Up
Cylindric lenses
180 mJ / 10 Hz
LaK8
Prisms
Output
40 µJ
10 Hz
Øx,FWHM = 4000 µm
Øy,FWHM = 600 µm
Left Side
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Nd:YAG
Multipass amplifier
6 passes
Ti:Sa Absorption : 90%
Ø = 15 mm
Øx,y,FWHM = 10 mm
Output Beam
Pump
Øx,FWHM = 4000 µm
Øy,FWHM = 600 µm
Right Side
UMR 7639
Experiment Set Up
Cylindric lenses
180 mJ / 10 Hz
LaK8
Prisms
Output
28 mJ
~ 1,8 J/cm²
Nd:YAG
Multipass amplifier
6 passes
Ti:Sa Absorption : 90%
Ø = 15 mm
40 µJ
10 Hz
FFT Calculation
1,00E+00
0,8
0,6
0,4
0,2
Normalized Intensity (a.u.)
1,0
Normalized Intensity (a.u.)
Normalized Intensity (a.u.)
1,0
0,8
0,6
0,4
0,2
0,0
745
770
795
820
845
Wavelength (nm)
Simulation
CPA
http://loa.ensta.fr/
870
1,00E-02
1,00E-03
1,00E-04
1,00E-05
0,0
720
1,00E-01
720
745
770
795
820
845
Wavelength (nm)
Experiment
STCPA
870
-100
-50
0
Duration (fs)
UMR 7639
50
100
Experiment Set Up
Cylindric lenses
180 mJ / 10 Hz
LaK8
Prisms
Output
28 mJ
~ 1,8 J/cm²
Nd:YAG
Multipass amplifier
6 passes
40 µJ
10 Hz
Ti:Sa Absorption : 90%
Ø = 15 mm
Near field
Far field
No angular and transverse chirp
http://loa.ensta.fr/
UMR 7639
Conclusion
• First amplification scheme in Ti:Sa using a combination of
spatial and temporal chirp
• STCPA concept avoids effects of saturation / enables a
control of the amplified spectrum at high energy
• Using appropriate chirp tool : output beam free of angular
and transverse chirp
• Fully relevant technique for obtaining very intense and
short laser pulses (energy in excess of 10’s of Joules) with
good temporal quality
http://loa.ensta.fr/
UMR 7639
Thank you !
http://loa.ensta.fr/
UMR 7639