Palaiseau - FRANCE 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, 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 ) Input : Δλ½ = 85 nm Pass 6 : Δλ½ = 62 nm http://loa.ensta.fr/ UMR 7639 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 ) Input : λc = 794 nm Pass 6 : λc = 808 nm Duration (ps) http://loa.ensta.fr/ UMR 7639 Frantz et Nodvik model : « Saturation regime : J0(t) ~ Jsat / G = 1,8 » 

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). 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). 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. Oscillator Stretcher Power amplifier Compressor Classical CPA scheme Ti:Sa Crystal Pump Beam IR Beam 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 STCPA scheme Spatial spreading Spatial compression Oscillator Stretcher 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 http://loa.ensta.fr/ UMR 7639

Experiment Set Up Frequency doubled Nd:YVO4 3,7 W Ti:Sa Oscillator 3,8 nJ / 80 MHz http://loa.ensta.fr/ UMR 7639

Öffner triplet Stretcher Experiment Set Up Frequency doubled Nd:YVO4 3,7 W Öffner triplet Stretcher Ti:Sa Oscillator 250 ps 3,8 nJ / 80 MHz http://loa.ensta.fr/ UMR 7639

Regenerative Amplifier Öffner triplet Stretcher Experiment Set Up Frequency doubled Nd:YVO4 1,5 mJ 1 kHz 3,7 W Regenerative Amplifier Öffner triplet Stretcher Ti:Sa Oscillator 7,1 mJ / 1 kHz 250 ps 3,8 nJ / 80 MHz Q-switched Nd:YLF http://loa.ensta.fr/ UMR 7639

Regenerative Amplifier Öffner triplet Stretcher Experiment Set Up Frequency doubled Nd:YVO4 500 µJ 1 kHz + Birefringent Plate 3,7 W Regenerative Amplifier Öffner triplet Stretcher Ti:Sa Oscillator 7,1 mJ / 1 kHz 250 ps 3,8 nJ / 80 MHz Q-switched Nd:YLF http://loa.ensta.fr/ UMR 7639

Regenerative Amplifier Öffner triplet Stretcher Experiment Set Up Cylindric lenses 180 mJ / 10 Hz Nd:YAG LaK8 Prisms Multipass amplifier 6 passes Ti:Sa Absorption : 90% Output Ø = 15 mm 40 µJ 10 Hz Frequency doubled Nd:YVO4 Pockels Cell 500 µJ 1 kHz + Birefringent Plate 3,7 W Regenerative Amplifier Öffner triplet Stretcher Ti:Sa Oscillator 7,1 mJ / 1 kHz 250 ps 3,8 nJ / 80 MHz Q-switched Nd:YLF http://loa.ensta.fr/ UMR 7639

Experiment Set Up Cylindric lenses 180 mJ / 10 Hz Nd:YAG LaK8 Prisms Multipass amplifier 6 passes Ti:Sa Absorption : 90% Output Ø = 15 mm 40 µJ 10 Hz IR Beam Before Prisms IR Beam After Prisms Øy,FWHM = 1900 µm Øx,FWHM = 3000 µm Øx,y,FWHM = 1900 µm http://loa.ensta.fr/ UMR 7639 Aspect Ratio of 1,6

Experiment Set Up Cylindric lenses 180 mJ / 10 Hz Nd:YAG LaK8 Prisms Multipass amplifier 6 passes Ti:Sa Absorption : 90% Output Ø = 15 mm 40 µJ 10 Hz IR Beam After Prisms Wavelength spreading 19 nm/mm Øy,FWHM = 1900 µm Øx,FWHM = 3000 µm http://loa.ensta.fr/ UMR 7639

Experiment Set Up Cylindric lenses 180 mJ / 10 Hz Nd:YAG LaK8 Prisms Multipass amplifier 6 passes Ti:Sa Absorption : 90% Output Ø = 15 mm 40 µJ 10 Hz Left Side Øy,FWHM = 600 µm Øx,FWHM = 4000 µm Output Beam Pump Øx,y,FWHM = 10 mm Right Side Øy,FWHM = 600 µm Øx,FWHM = 4000 µm http://loa.ensta.fr/ UMR 7639

Experiment Set Up Output 28 mJ ~ 1,8 J/cm² Cylindric lenses 180 mJ / 10 Hz Nd:YAG LaK8 Prisms Multipass amplifier 6 passes Output 28 mJ ~ 1,8 J/cm² Ti:Sa Absorption : 90% Ø = 15 mm 40 µJ 10 Hz FFT Calculation Simulation CPA Experiment STCPA http://loa.ensta.fr/ UMR 7639

No angular and transverse chirp Experiment Set Up Cylindric lenses 180 mJ / 10 Hz Nd:YAG LaK8 Prisms Multipass amplifier 6 passes Output 28 mJ ~ 1,8 J/cm² Ti:Sa Absorption : 90% Ø = 15 mm 40 µJ 10 Hz Far field Near field http://loa.ensta.fr/ UMR 7639 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 http://loa.ensta.fr/ UMR 7639

Thank you ! http://loa.ensta.fr/ UMR 7639