1. Amplificarea pulsurilor laser ultrascurte. CPA in Ti:safir sau OPCPA? Solutii pentru laserul ELI-RO. (Partea III) R. Dabu Sectia Laseri, INFLPR

2. CUPRINS 1. Amplificarea pulsurilor laser cu deriva de frecventa (“chirped pulse amplification” - CPA) in Ti:safir. - Caractersiticile Ti:safir ca mediu amplificator laser. - Probleme legate de amplificarea pulsurilor de femtosecunde de mare energie. 2. Ce este amplificarea parametrica si, in particular, OPCPA. - Oscilatia, generarea si amplificarea parametrica ca fenomene in optica neliniara. - Relatiile care guverneaza fenomenele parametrice. - Castigul unui amplificator parametric, banda de frecventa. 3. Amplificare parametrica optica (OPA) de banda larga si de banda foarte larga. - Conditiile de obtinere a amplificarii parametrice de banda larga sau foarte larga. - Cum se calculeaza pentru un cristal dat parametrii de functionare in cele doua cazuri. - Potentialul aplicarii pentru laserii cu pulsuri ultrascurte de mare putere. - Amplificarea parametrica a pulsurilor largite cu deriva de frecventa – OPCPA. - Metode de obtinere a amplificarii de banda larga: la degenerescenta, amplificare necoliniara, folosirea mai multor laseri de pompaj. Exemple. - Metode de obtinere a amplificarii de banda foarte larga. Benzile de amplificare foarte larga in cristale BBO si DKDP pentru laserii din clasa PW. 4. Prezentarea unor sisteme laser amplificatoare in domeniul PW: - Laserul rusesc cu oscilator in fs la 1250 nm (Cr:forsterite) si amplificare in cristale DKDP. - Laserul englez (910 nm) cu amplificare de mare energie in DKDP. - Laserul german cu amplificare pe ~ 900 nm. - Laserul francez cu amplificare pe 800 nm in BBO si Ti:safir. - Comparatie intre diferite sisteme de amplificare (China, Korea, Japonia, Rusia, Franta, Germania si Anglia). OPCPA versus amplificare in Ti-safir: avantaje si dezavantaje. 5. Care ar fi cea mai buna solutie pentru laserul ELI-RO? Ce e de facut pentru realizarea la timp si la parametrii propusi a sistemului laser ELI-RO?

3. Solutii posibile pentru generarea de pulsuri laser multi- PW cu durata de femtosecunde 1. OPCPA - large aperture nonlinear crystals, ultra-broad bandwidth non-collinear phase-matching geometry 2. Amplification in large aperture Ti:sapphire crystals, broad bandwidth with ~ 800 nm central wavelength.

4. OPCPA – phase matching conditions in uniaxial nonlinear crystals 1. Collinear phase-matching 2. Non-collinear phase-matching, broad bandwidth → → → 3. Non-collinear phase-matching, ultra-broad bandwidth Uniaxial crystal, Sellmeier equations:

5. Multi-PW femtosecond laser amplifiers based on chirped pulse amplification 1.OPCPA - large aperture (200-300 mm) DKDP crystals, ultra-broad bandwidth with ~ 900 nm central wavelength. 10-15 fs re-compressed pulse duration, 2. Amplification in large aperture (100-200 nm) Ti:sapphire crystals, broad bandwidth with ~ 800 nm central wavelength. 20-30 fs re-compressed pulse duration 3. Flash-lamp/diode pumped Nd/Yb glasses, 1054/1030 nm - Hybrid Ti:sapphire-Nd:glass laser system, Lawrence Livermore National Laboratory (LLNL), USA - All-diode-pumped Yb-doped fluoride phosphate glass laser system, POLARIS project, Jena, Germany 4. Nanosecond Nd:glass pumped polycrystalline Cr-doped ceramics, 100-PW laser concept – Nijnii Novgorod, Russia

6. Laser system AmplificationReported characteristicsProjectConcept PEARL- Russia OPCPA - DKDPλ = 910 nm, τ = 43 fs, R = 1shot/30 min, P = 0.56 PW P = 2 PW PFS- Germany OPCPA - DKDPλ = 900 nm, τ ≈ 5 fs, R = 10 Hz, P ≈ 1 PW RAL-UKOPCPA - DKDPλ = 910 nm, τ = 15-30 fs, R =1 shot/30 min, P ≈ 10 PW XL III - ChinaTi:sapphireλ = 800 nm, τ = 31 fs, R = 1shot/20 min, P = 0.72 PW P > 1 PW APRI - KoreaTi:sapphireλ = 800 nm, τ = 30 fs, R = 10 Hz, P = 100 TW P = 1.1 PW, R = 0.1 Hz P → 10 PW JAERI - Japan Ti:sapphireλ = 800 nm, τ = 33 fs, R=Few shots/hour, P = 0.85 PW APOLLON - France Hybrid: OPCPA&Ti:S λ = 800 nm, τ = 15-20 fs, R = 1 shot/min, P ≈ 10 PW LLNL - USANd:glassλ = 1053 nm, τ = 440 fs, R = 1-2 shots/hour, P = 1.5 PW POLARIS - Germany Yb:fluoride phosphate glass λ = 1032 nm, τ = 150 fs, R = 0.1 Hz, P = 1 PW N-Novgorod, Russia Cr-doped ceramics λ = 1378 nm, τ = 25 fs, R ≈ 1 shot/hour, P → 100 PW λ = central wavelength, τ = pulse duration, R = repetition rate, P = peak power PW Laser Systems: reported, projects, concepts

7. LLNL – 1.5 PW laser system M.D. Perry et al., Opt. Lett. 24, 160 (1999) Kerr-lens mode-locked Ti:S oscillator at 1054 nm, 16.5 nm bandwidth after stretcher Two Nd:YAG pumped Ti:S regenerative amplifiers (linear & ring), ~ 50 mJ, 7 nm, 1.4 ns pulses at 1054 nm central wavelength Three Nd:phosphate glass rod amplifiers, 15 J, 5.3 nm, 900 ps output pulses Nd:glass disk amplifier section (NOVA laser), 1120 J, 3.8 nm, 800 ps, 56.3 cm beam diameter laser pulses before compressor Compressor: a pair of two 94-cm-diameter gratings, 880 J input pulse, 660 J, 440 fs compressed pulse Focused peak irradiance: 0.7 x 10 21 W/cm 2 Drawbacks: high energy consumption, thermal problems of glass amplifiers, low repetition rate

8. J. Hein et al., Appl. Phys. B 79, 419 (2004) POLARIS project - concept Laser amplifiers: Yb-doped fluoride phosphate glass pumped, all-diode-pumped at 940 nm, 2.6 ms pulses Operational up to 1.25 J pulse energy, 0.2 Hz, 12 nm bandwidth, 135 fs re-compressed pulses (2004) Aim: 1 PW, 0.1 Hz

9. 100-PW – concept Nijnii Novgorod, Russia E. A. Khazanov and A. M. Sergeev, Laser Physics 17, 1398 (2007) Polycrystalline Cr-doped ceramics: Cr:YAG (Y 3 Al 5 O 12 ), Cr:YSGG (Y 3 Sc 2 Al 3 O 12 ) Cr:YAG ceramic disk laser pumped by one channel (of four) of the high-power laser fusion facility “Luch”. Pump energy 3. 3 kJ at 1053 nm Each disk 80 x 40 cm 2 aperture Preamplification stages (from nJ to few J) based on OPA (idler of broad-band 800-900 nm signal in BBO) Central wavelength - 1378 nm, 224-nm bandwidth Input energy 20 J, output energy 1100 J. Expected pulse duration 25 fs, peak power 32 PW. Key properties of polycrystalline Cr:YAG ceramics: - large-gain bandwidth (20-fs pulse duration) - wide aperture to amplify chirped pulses up to multi-kJ level - high efficiency conversion for narrow-band Nd:glass laser pump.

10. Few-tens-femtosecond PW class lasers (table-top !?) over the world 1.OPCPA laser systems -Nijnii-Novgorod, Russia -Rutherford Appleton Laboratory, UK (10 PW class) -PFS, MPQ Garching, Germany 2. Ti:sapphire amplification -XL III, Beijing, China -Center for Femto-Atto Science and Technology & Advanced Photonics Research Institute, Korea -Japan Atomic Energy Research Institute (JAERI), Kyoto, Japan (0.85 PW, 33-fs) 3. Hybrid laser system (Front_End - OPCPA & High Energy Amplifiers - Ti:sapphire) -Apollon 10, Paris, France (10 PW class)

11. OPCPA 0.56 PW laser – Nijnii Novgorod, Russia Electronic synchronization of pump and signal pulses. OPA III, KD*P crystal 80-mm length, 120-mm clear aperture. Rep rate: 1 pulse/30 minutes In the ns time gate (during pump pulse duration), intensity contrast ~ 10 -8 It takes a couple of hours for fine alignment Room surface ~ 80 m 2 V.V. Lozhkarev et al, Laser Phys. Lett., No. 6, 421 (2007) Oscillator, relatively narrow band-width OPA I, signal angular dispersion ? Optical components damage?

12. PEtawatt pARametric Laser (PEARL)

13. OPCPA scalability to multi-petawatt power. Sarov – N.Novgorod. Second phase (PW level) 38J 0.5ns Compressor 0.5ns  50fs 22 Nd:glass amplifier 300J 1ns 180J 1ns 24J 43fs OPA III KD*P 10cm dia 22 Cr:Forsterite fs-laser =1250nm Stretcher 40 fs  0.5 ns 2nJ 40 fs 1nJ 0.5 ns Nd:YLF Q-switch laser =1053nm 1 J 1.5ns Synchronization system Two-stage Nd:YLF amplifier First phase ( TW level) 32 mJ 70 fs 2 Hz OPA I KD*P Compressor 0.5 ns  70 fs =911nm 0.8mJ 0.5ns 2J 1.5 ns OPA II KD*P CW Yb:fiber pump 10W =1050…1080nm =1250nm =911 nm 70 mJ 0.5 ns 1mJ 1.5ns 10mJ 12ns Pulse shaper Third phase ( 2 PW) 22 Nd:glass amplifier 2kJ 1.5ns 1kJ 1.5ns 150J 0.5ns 100J 50fs Compressor 0.5ns  50fs OPA IV KD*P 20cm dia Nd:YLF Q-switch laser =1053nm 10mJ 12ns Pulse shaper Nd:YLF amplifier

14. RAL Laser, UK, OPCPA at 910 nm in large DKDP crystals - concept Seed laser source: as presented in the following slide

15. Short-pulse source at 910 nm –suitable seed for high energy OPCPA system Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Oxon, UK Linearly negative GVD stretched pump seed pulses ~ 2 nm/ps SHG at 400 nm in 0.2 mm BBO crystal, ~ 6.8 nm bandwidth, 110 μJ pulse energy, 1 nm/ps linear chirp Signal seed pulse at 714 nm; the air and glass stretcher were adjusted to get the desired combination of nonlinear and linear signal chirp (18 nm/ps) Idler at 910 nm, 7 μJ pulse energy, 165 nm bandwidth, was obtained after two- pass amplification. Calculated Fourier transform-limited pulse duration ~ 14.5 fs. Y.Tang et al, Opt. Lett, Vol. 33, 2386 (2008)

16. Max-Planck-Institut für Quantenoptik Ludwig-Maximilians Universität München 5 fs 3 J 10 Hz High bandwidth (OPCPA) Large crystals High – rep. pump Yb:YAG CPA pump laser Large aperture DKDP OPCPA bulk/chirped mirror compression Diode pumping Thin KDP or DKDP CPA High pump intensity ps pulse duration Petawatt Field Synthesizer (PFS) strategy Z. Major, LEI, Oct 2009, Brasov

17. Basic concept and layout of Petawatt Frequency Synthesizer - PFS MPQ Garching, Germany Z. Major, LEI, Oct 2009, Brasov Yb:YAG, 1030 nm, ~3.5 nm bandwidth

18. Zs. Major et al., Review of Laser Engineering, 37, 431 (2009) OPCPA design Large aperture DKDP crystals Lozhkarev et al. Laser Phys. Lett. 4, 421 (2007) Total pump energy: 20 J @ 515 nm 1D modelling with saturation (pump depletion) no dispersion included stagepump energy ampl. signal energy crystal length 12.5 mJ500 µJ3.8 mm 220 mJ3.5 mJ3.8 mm 3200 mJ40 mJ3.5 mm 41 J169 mJ3.0 mm 53 J722 mJ2.8 mm 65 J1.7 J2.4 mm 75 J2.8 J1.7 mm 85 J3.8 J1.5 mm

19. Front-End PFS Garching Difference in optical paths of the pump and OPCPA seed pulses, 75-80 m Expansion coefficient of stainless steel, 13 x 10 -6 K. 1 K → ~ 3 ps Drift between two oscillator pulses: 3 ps (first 150 minutes), later reaches 100 fs. HCF2 output spectrum, 0.2 mJ supercontinuum energy I. Ahmad et al., Appl. Phys. B, 97, 529 (2009)

20. 50J/527nm pump laser Amplifier II Amplifier I CW 532nm pump laser fs oscillator 500mW/20fs 20J/40fs ～ 500TW Target Chamber II Pre-pulse Generator 600mJ/30fs ~20TW Target Chamber I Final amplifier ~30J/800nm/20min 1m Area for power supply, 1X6 meters Control Platform Door Clear door Room size: 14X8 meters Compressor I 50J/527nm Pump laser 3J/532nm/1Hz 500mJ/10Hz 532nm SF Laser Compressor II Layout of XL III Offern Stretcher Institute of Physics Chinese Academy of Science, Beijing, China. 100190, LEI-2009,Brasov 11J/31fs = 355TW, in 200522.5J/31fs >720TW, in 2008

21. Development of output power Peak Power (TW) ? What will be next? Answer: >1PW will be possible with available pump energy, but contrast ratio and beam quality are most important issues.

22. 22 Specifications: Stability: <  1% Average power: >500mW Pulse duration: ~ 20fs Peak power: >0.3MW Tunable range: 740~860nm Repetition rate: ~100MHz Femtosecond Ti:sapphire Oscillator

23. New configuration of front stage OscillatorStretcher ILinear Reg AmpCompressor IXPW filter Stretcher II Ultra-long Ring-reg Amp Boost AmpMain AmpCompressor II cryogenic cooling system Nd:YLF pump laser DCPA+XPW+ Ring regenerative amplifier with ultralong cavity length

24. 24 Second stage amplifier With 3J pump laser energy, amplified laser of 780mJ was obtained, corresponding to the efficiency of 27%

25. 25

26. The output energy of 527nm: Beam A: E=69.9J Beam B: E=53.04J Layout of 100J pump laser Beamtech Inc ， China Recent upgrade allow the total energy to 120J

27. Ti:sapphire Crystal  80×40mm MP4 PC Pumped the final amplifier with 110J laser at 527nm, laser energy only 45J was obtained. Double increasing compare early result in 2005. Design of final amplifier

28. Liquide IN Liquid OUT Laser beams Enhancement of laser energy in main amplifier With new crystal of f80X40mm in size, 45J laser energy was obtained by eliminate the parasitic lasing and enlarge the beam diameter to 70mm.

29. Prospect and conclusion  Replace the liner regenerative amp in the 1 st CPA as multipass scheme.  Add a multipass stage at repetition rate 0.1Hz before the main amplifier in 2 nd CPA  Seeding with high contrast ratio pulse, such as OPO etc.  Mixing pump of multi-beams  Promise to Contrast ratio higher than 10 10 in 10 ps range, Beam quality better than 1.2 DL, Peak power larger than 1PW (>30J/30fs),

30. 0.1-Hz 1-PW Ti:Sapphire Laser facility Seong Ku Lee, Tae Jun Yu, Jae Hee Sung, Tae Moon Jeong, Il Woo Choi, and Jongmin Lee Center for Femto-Atto Science and Technology & Advanced Photonics Research Institute, Korea

31. Layout of Ultrashort Quantum Beam Facility PW Laser-Plasma Lab. 100-TW Laser-Plasma Lab PW amplifier 1 PW x 2 100 TW system Target 1 (proton) Target 2 (electron) Compressor PW Target 1 PW Target 2 Target 3 (x-ray) PW Laser Lab.

32. 2nd Power Amp. 4.8 J, 10 Hz Booster Amp. 50 J, 0.1 Hz Multi-pass 1 mJ, 1 kHz Pre-amplifier 50 mJ, 10 Hz 1st Power Amp. 1.8 J, 10 Hz PW Compressor Oscillator < 10 fs, 75 MHz Nd:Glass laser 100 J, 0.1 Hz Booster Amp. 50 J, 0.1 Hz PW Compressor Nd:Glass laser 100 J, 0.1 Hz PW Target Chamber Target Chamber Schematic of Laser System 100 TW Compressor Grating Stretcher ~ 0.5 ns PW laser system Grating Stretcher ~ 1 ns Schematic of Laser System

33. View of Laser System 100 TW system PW Amp. IIPW Amp. I

34. Ti:sapphire crystal Absorption coeff. = 1.1 cm -1 L = 25 mm Parasitic Lasing Suppression 50 J Transverse Fresnel reflection at Ti:sap. crystal induces transverse parasitic lasing. Cladding material Di-iodomethane Derivative (Cargille Laboratories) Absorption of transmitted spontaneous emission Laser dye (HITC-iodide, Exciton) Fabien Ple, Opt. Lett. 2007.

35. Wavelength: 527 nm Energy: 8.5 J x 3 beams Pulse width: 30 ns Rep. rate: 0.1 Hz 3-pass amplification 3D View of PW Amplifier I

36. Spatial Intensity Profiles of the Amplified Output Beam Flat-top intensity profile

37. Preliminary Pulse Compression Energy Attenuation & 2 grating compressor Pulse duration measurement by single shot SPIDER Grating efficiency: 69.3%  = 30 fs (FWHM)  (T.L.) = 25 fs

38. PW Vacuum Compressor (under Construction) Grating damage threshold (150 mJ/cm 2 ) Dia. ~ 200 mm 1 st & 4 th Grating Size : 390 * 245 mm 2 nd & 3 rd Grating Size : 560 * 245 mm

39. Summary  Ultrashort quantum beam facility (UQBF) project in Advanced Photonics Research Institute (APRI), aims to develop a 0.1-Hz Pettawatt Ti:sapphire laser system based on chirped pulse amplification (CPA).  We have developed a high-energy Ti:sapphire amplifier for 1-PW laser operating at 0.1 Hz rep. rate.  Parasitic lasing suppression & Flat-top pump beam profile - Energy: 46.3 J  0.24J (max., 46.8 J) and flat-top intensity profile  Spectral dispersion compensation - Pulse duration: 30 fs  0.75 fs (min., 28.1 fs) 1.1 PW laser pulse generation at 0.1 Hz rep. rate is expected PW amplifier II will be established within 2011 2 PW laser-material interaction experiment Dual PW laser experiment: Compton scattering etc. One PW beam will be upgraded up to 10 PW.

40.  180 mm  520 mm  200 mm  520 mm DM1 DM2 SF G1 G2 G2b G3 G4 G3b Vacuum compression / spatial beam control 150J / 15 fs @1shot/mn 10 PW Ampli 0 2J /1Hz Nd YAG 6J/1Hz Ampli 1 « LASERIX » 50J /0.1Hz Nd Glass 100J/0.1Hz Ampli 2 600J -1shot/mn Nd Glass 1.5KJ – 1shot/mn Amplifiers synchronized OPCPA Amplification stages LBO/BBO KHz Ti:Sa 30 fs @ 800 nm 500 µJ Spectral broadening < 10 fs @ 800 nm 100 µJ, kHz Yb:KGW Diode pumped 300 fs, 200 µJ @ 1030 nm Amplis Yb:KGW Yb:YAG Diode pumped 2 J @ 1030 nm 1Hz 10 fs @ 800 nm 100 mJ, 1Hz Front End Compression and SHG 1 à 100 ps 1 J @ 515 nm 1 Hz ILE APOLLON Single beamline 10PW laser ILE – APOLLON 10P : A collaborative project LEI Conference, Brasov (RO) October 21rst, 2009

41. The ILE APOLLON 10P Front End ps/ns strategy NOPCPA (x100-200) (BBO, LBO or BIBO) 1-2 stages Ti:Saphir 25 fs @ 800 nm 1.5 mJ/1kHz Spectral broadening < 10 fs @ 800 nm 200 µJ, kHz Hollow fiber + XPW Yb:KGW Regen. >500 ps, 2 mJ @ 1030 nm 3D MP Amp Yb:KGW (1030nm, 3.5nm) 20-30 mJ 100Hz SHG >50% 10-20 mJ <10 fs @ 800 nm 100Hz (to1kHz) Glass stretcher Optical synchronization CM compr. 100 mJ, ~30 ps @515nm >100 µJ @800nm 10 ps >10-20 mJ @800nm 10 ps Compr. ~50 ps Stretcher >500 ps 10-20 mJ @800nm Offner stretcher ~1ns, ~30% NOPCPA (x30-50) (BBO, LBO or BIBO) 1-2 stages >100 mJ ~1ns (<10fs) @ 800 nm 100Hz 3D MP Amplifiers (2-3) Yb:KGW and Yb:YAG ~3 ns, 2 J, 1030 nm,10Hz SHG ~50% Offner stretcher 1-1.5 ns/nm 20-30% 20 mJ @1030 nm >6 mJ @1030 nm ~1 J, ~2ns @515nm 3-6 mJ @800nm Picosecond Stage Nanosecond Stage Thin Disk Regen. Yb:YAG (1030nm, 3nm) 200-300mJ 100Hz D AZZLER Thin Disk Amp Yb:YAG ~3 ns, 2 J, 1030 nm,100Hz LEI Conference, Brasov (RO) October 21rst, 2009

42. ILE – APOLLON 10P : the French ELI single line prototype TiSa power amplifiers section LEI Conference, Brasov (RO) October 21rst, 2009

43. Collaborative R&D with industries for overcoming ILE /ELI Bottlenecks on pump lasers Big international tender launched in January 2009 (4 years) called « Competitive dialog procedure » TiSa large pump lasers (ns) LEI Conference, Brasov (RO) October 21rst, 2009 Laurence Livermore Nat Lab 200J of green /nanosecond (20-30ns) / single beamline, >1shot/mn

44. Non-linear optical processes in PW femtosecond laser systems Ti:sapphire amplificationOPCPA Oscillator – self mode-locking (Kerr effect) Pump lasers – SHG Contrast improvement – XPW Oscillator – self mode-locking (Kerr effect) Pump lasers – SHG Contrast improvement – XPW PFS, Munchen: 2 x Spectral brodening in hollow-core fiber (HCF) 1 x Soliton frequency shift in photonic crystal fiber (PCF) 7 x DKDP-OPCPA amplifier stages Rutherford, UK: 1 x LBO linearly stretched pump, non-linearly stretched signal amplifier 6 x LBO, DKDP - OPCPA amplifier stages Nijnii-Novgorod, Russia: 3-4 x DKDP-OPCPA amplifier stages Apollon, France: 1 x Spectral broadening in HCF 3-4 x OPCPA amplifier stages (BBO, LBO)

45. High-energy OPCPA vs CPA Advantages of OPCPA:  Ultra-broad gain bandwidth (amplified pulses re-compressed down to 5-15 fs)  Considerable decrease in thermal loading  Significantly lower level of ASE  Very high gain  No self-lasing  High aperture DKDP crystals are available Disadvantages of OPCPA: - Exigent requirements: - High precision pump-signal pulse synchronization - High beam quality of pump lasers - Short (ps-ns) pump pulse duration  Intricate Front-End to generate ultra-broad bandwidth signal pulse and optically synchronized pump pulse  Low pulse to pulse stability? - High spectral sensitivity of NOPCPA to small changes of the cross-angle between interacting waves - High-energy amplification chain is based on a cascade of nonlinear optical processes Advantages of Ti:sapphire CPA: + Relatively simple Front-End + Easy pump-signal pulse synchronization + Less restricted characteristics of pump laser + Technical solutions validated by the production of many commercial lasers Disadvantages of Ti:sapphire CPA: - Limited gain bandwidth (amplified pulses re-compressed to > 20 fs) - Thermal loading - Special optical/electro-optical components necessary to improve ps-ns intensity contrast - Currently available Ti:sapphire rods ≤ 100 mm diameter - Self lasing

46. Energy consumption (estimation) to get a single 1-PW laser pulse Electrical energy Nanosecond pump lasers SHG Ti:sapphire amplifiers Nd:glass amplifiers Laser diodeYb:glass amplifiers Compressor Short-pulse nanosecond pump lasers SHG OPCPA amplifiers Fs pulse Amplification methods Nd Pulse duration [fs] Pulse energy after compressor [J] Energy consumption/ 1-PW laser pulse [kJ/pulse] Pulse energy/ energy consumption [J/kJ] Repetition rate Ti:sapphire amplification 25 102.5Medium (0.01-0.1 Hz) OPCPA15 101.5Medium (0.01-0.1 Hz) LLNL (flash-lamp pumped Nd:glass) 450 3015Low (1-2 pulses/hour) POLARIS (diode pumped Yb:glass) 150 720High (0.1-1 Hz) Cr-doped ceramics (ns Nd:glass pumped) 25 55Low (1-2 pulses/hour) Ns Nd:glass Cr-doped ceramics disk amplifiers

47. Selection criteria for ELI-RO laser system 1. Able to fulfill required specifications: - Peak pulse power ~ 10 PW per one amplifier chain - Pulse-width of the re-compressed amplified pulse < 30 fs - Rep-rate 1/10 – 1/60 Hz - Ns & ps contrast > 10 12 - Focused laser intensity 10 23-24 W/cm 2 (Laser beam focused near the diffraction limit) 2. Existing techniques proved by the long term laser facilities operation (200 TW Ti:sapphire CPA laser systems) 3. Existing laser components and devices necessary to reach 10 PW power (e.g. ~ 30 cm diameter DKDP crystals) 4. Required laser components and devices that could be probably developed in the next years (20- cm diameter Ti:S rods; Nd:YAG, Yb:YAG, Nd:glass, diode pump lasers; diffraction gratings, etc.) 5. Conditions of operation and expected laser system long-term stability 6. Costs of the whole laser system 7. Energy consumption/laser pulse

48. Solutii posibile pentru laserul ELI-RO 1.Laser hibrid cu amplificare in banda de 800 nm: -Front-End bazat pe OPCPA in cristale neliniare (BBO, LBO) -Amplificare la energie mare in Ti:safir 2. Amplificare in Ti:safir in banda de 800 nm: - Front-End cu amplificare in Ti:safir - Amplificare la energie mare in Ti:safir Laser bazat pe OPCPA in banda de 910 nm: - Front-End → generarea semnalului de banda foarte larga la 910 nm prin amplificare cu adaptare de faza coliniara si cu deriva de frecventa compensata (“chirp-compensated OPCPA”) - OPCPA la mare energie in cristale DKDP SAU Solutie propusa

49. Poate fi sistemul TEWALAS un Front-End pentru laserul ELI-RO? Modificari neaparat necesare: - Marirea duratei pulsului “stretched” de la ~ 300 ps la 2-3 ns - Imbunatatitrea contrastului ASE si pre-pulsuri (double CPA, XPW, celule Pockels, Multi-pass amplifier sau Ring regenerative amplifier?) -Control termic al breadboard-urilor pe care sunt montate modulele sistemului laser Imbunatatiri care usureaza modul de operare si duc la cresterea fiabilitatii: -Perfectionarea modului de lucru cu sistemul de control al fazei si spectrului (Mazzler & Dazzler) - Introducerea unui sistem automatizat de control al alinierii optice in lantul de amplificare - Folosirea unui oscilator cu stabilitate de lucru pe termen mai lung (unghiulara, spectrala) Laserul proiectului CETAL ar putea fi conceput conform cerintelor de mai sus Concluzie: sistemul laser existent nu poate fi un Front-End valabil pentru un laser din clasa PW-multiPW

50. 10 PW laser, a very difficult task (high risk project): X 50 more powerful than any existing femtosecond commercial laser X 20 more powerful than any existing femtosecond laboratory laser system X 500 more powerful than femtosecond TEWALAS laser at INFLPR Factors of (high) risk: - high energy (200-300 J/pulse) laser amplifier - re-compression of stretched amplified pulses and laser beam focusing - expected results of nuclear physics experiments

51. Cateva conditii pentru implementarea proiectului ELI-RO 1.Elaborarea unei strategii coerente care sa tina cont de existenta celor doua proiecte: CETAL si ELI-RO 2.Concentrarea eforturilor pe o directie prioritara, finantare prioritara 3. Gasirea unei forme de organizare legala care sa permita crearea unei entitati din care sa faca parte cu responsabilitati ferme companii si/sau specialisti din strainatate cu experienta in ingineria sistemelor laser in femtosecunde de mare energie Exemple de activitati pe termen scurt-mediu: ● Largirea echipei de lucru cu persoane care sa se implice si sa se specializeze exclusiv pentru acest proiect ● Trimiterea a 1-2 tineri sa lucreze in echipe din strainatate, de exemplu la: Institut d’Optique, firme (Amplitude Technologies?, Thales?) ● Contactarea directa a unor firme a caror tehnologie este decisiva pentru dezvoltarea laserilor din clasa PW, de exemplu: Femtolasers (Austria), Spectra Physics, CONTINUUM, National Energetics, Crystal Systems (USA), Thales, Amplitude Technologies (Franta), Night N (Rusia) - Discutie in 18 februarie cu reprezentantii firmei CONTINUUM la Bucuresti ● Implicarea in proiectarea, constructia si punerea in functiune a laserilor de 1 PW si de 10 PW a unei firme din strainatate cu experienta mare in domeniul ingineriei sistemelor laser cu pulsuri ultrascurte (de ex: Amplitude Technologies, Thales, National Energetics)

52. Care sunt sansele de a avea la Magurele in functiune in anul 2015 un laser in femtosecunde capabil sa genereze o putere pe puls de 10 PW, focalizat cu o intensitate >10 23 W/cm 2 ? Daca va fi in functiune un astfel de laser in 2015 la Magurele, cred ca va fi primul din lume cu aceste performante MULTUMESC PENTRU ATENTIE!