Spatio-Temporal Chirped Pulse Amplification for Avoiding Spectral Modifications in Ultra- Short...

Spatio-Temporal Chirped Pulse Amplification for Avoiding Spectral

Modifications in Ultra-Short Petawatt Lasers

C. Radier1,2, F. Giambruno1,3, C. Simon-Boisson2, V. Moro2, G. Chériaux1

1 LOA, Chemin de la Hunière, 91761 Palaiseau Cedex, France2 TOSA-DSL, 2 Avenue Gay Lussac, 78995 Elancourt, France

3 ILE, CNRS, Ecole Polytechnique, ENSTA, Institut d’optique, 91761 Palaiseau Cedex, France

[email protected]

Palaiseau - FRANCE

Context (1/2)

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

• 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

1,20

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Wavelength (nm)

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ain

(u

.a.)

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Wavelength (nm)

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.a.)

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 )

Input : Δλ½ = 85 nm

Pass 6 : Δλ½ = 62 nm

Frantz et Nodvik model : « Gain regime : J0(t) ~ Jsat / 1000 & G = 100 »

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 )

0,00

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Wavelength (nm)

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ized

sp

ectr

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sity

(u

.a.)

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-1500 -1000 -500 0 500 1000 1500

Wavelength (nm)

No

rmal

ized

sp

ectr

al g

ain

(u

.a.) Input : λc = 794 nm

Pass 6 : λc = 808 nm

Frantz et Nodvik model : « Saturation regime : J0(t) ~ Jsat / G = 1,8 »

Duration (ps)

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. 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). 2. 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).3. H. Takada, et al., “High-repetition-rate 12fs pulse amplification by a Ti:sapphire regenerative amplifier system,” Opt. Lett. 31, 1145–1147 (2006).4. L. Antonucci, et al., “14 fs high temporal quality injector for ultra-high intensity laser,” Opt. Commun. 282, 1374–1379 (2009). 5. 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).

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





Oscillator Stretcher Power amplifier Compressor

Classical CPA scheme

Ti:Sa Crystal

Pump Beam

IR Beam





STCPA scheme Spatial spreading Spatial compression

Oscillator Stretcher Power amplifier Compressor

Gain zone shape adaptation

Ti:Sa Crystal

Pump Beam

IR Beam



• 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 collimatedSpatial spreading law has to be inverse of that of spatial compressionPump beam has to be matched to the oblong seeded beam

• Inconvenient :Gain narrowing not avoided in this configuration

Experiment Set Up


Ti:Sa Oscillator

Frequency doubledNd:YVO4

3,8 nJ / 80 MHz

3,7 W

Experiment Set Up


Öffner triplet Stretcher

Ti:Sa Oscillator


3,8 nJ / 80 MHz250 ps

3,7 W

Experiment Set Up


Regenerative Amplifier


Ti:Sa Oscillator


3,8 nJ / 80 MHz250 psQ-switched

Nd:YLF

3,7 W1,5 mJ1 kHz

7,1 mJ / 1 kHz

Experiment Set Up




Ti:Sa Oscillator



Nd:YLF

3,7 W500 µJ1 kHz

7,1 mJ / 1 kHz

+ Birefringent Plate

Experiment Set Up


Nd:YAG

LaK8 Prisms

Cylindric lenses

Multipass amplifier6 passes



Ti:Sa Oscillator


Output


Nd:YLF

180 mJ / 10 Hz

3,7 W500 µJ1 kHz

Pockels Cell

40 µJ10 Hz

Ti:Sa Absorption : 90%

7,1 mJ / 1 kHz

+ Birefringent Plate

Ø = 15 mm

Experiment Set Up


40 µJ10 Hz

Nd:YAG

Cylindric lenses


180 mJ / 10 Hz


OutputØ = 15 mm

Aspect Ratio of 1,6

IR Beam Before Prisms

Øx,y,FWHM = 1900 µm

IR Beam After Prisms

Øy,FWHM = 1900 µmØx,FWHM = 3000 µm

LaK8 Prisms

Experiment Set Up


Nd:YAG

Cylindric lenses


180 mJ / 10 Hz

40 µJ10 Hz


Wavelength spreading 19 nm/mm

OutputØ = 15 mm

LaK8 Prisms

IR Beam After Prisms


Experiment Set Up


Nd:YAG

Cylindric lenses


180 mJ / 10 Hz

40 µJ10 Hz


Output Beam Pump

Øx,y,FWHM = 10 mm

Right Side


Left Side


OutputØ = 15 mm

LaK8 Prisms

Experiment Set Up


Experiment STCPA

0,0

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0,6

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1,0

720 745 770 795 820 845 870

Wavelength (nm)

Nor

mal

ized

Inte

nsit

y (a

.u.)

Simulation CPA

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720 745 770 795 820 845 870

Wavelength (nm)

Nor

mal

ized

Inte

nsit

y (a

.u.)

Nd:YAG

Cylindric lenses


Output28 mJ~ 1,8 J/cm²

180 mJ / 10 Hz

40 µJ10 Hz

Ti:Sa Absorption : 90%Ø = 15 mm

LaK8 Prisms

1,00E-05

1,00E-04

1,00E-03

1,00E-02

1,00E-01

1,00E+00

-100 -50 0 50 100

Nor

mal

ized

Inte

nsit

y (a

.u.)

Duration (fs)

FFT Calculation

Experiment Set Up


Far field Near field

Nd:YAG

Cylindric lenses


Output28 mJ~ 1,8 J/cm²

180 mJ / 10 Hz

40 µJ10 Hz

Ti:Sa Absorption : 90%Ø = 15 mm

LaK8 Prisms

No angular and transverse chirp

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


Thank you !

Spatio-Temporal Chirped Pulse Amplification for Avoiding Spectral Modifications in Ultra- Short...

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