Business Development Manager, Bucarest 2011 Industrial approach and identifications of risks for multi-PW laser systems Franck FALCOZ Business Development Manager, Bucarest 2011 LM3 micro-machinning station with s-Pulse HP

Questions to be considered.. How to qualify a High Energy Femtosecond laser, and how to verify the performances of the laser chain? (large beam, ultrashort pulse durations, compression in vacuum, low rep rate…) What are the criteria for a supplier of a Ultra Intense Laser chain for proposing the right laser architecture : performances, reliability, upgradeability, man-machine interface….? Management of the risks : quality control of critical components (crystal, gratings…), stock of spare in case of failure… 2

Specificities in PW laser projects… Management of Risks… Specificities in PW laser projects… Project duration and PLM « Project/Product Lifecycle Management »: multi years program: project preparation, realization of the building with radioprotected zone welcoming the PW laser, commissioning of the facility: total duration could be longer than 5 years Important to structure the proposal in multi-steps approach ensuring at each step that the user will have an useable machine with « state-of-the art » performances…

Specificities in PW laser projects… Management of Risks… Specificities in PW laser projects… PW laser chain budgetary structure Laser chain is shared in 2 main parts: The « femtosecond laser part », technology and techniques involved in the chain The « pump lasers » part Each of them represents around 50% of the whole budget… Femtosecond part: Combination of Technologies, Technique and Engineering… Pump part: « tank of Green light” for pumping crystals… Key components for the reliability Risks of failure in PW laser development are definitely in the femtosecond part… 4

Reliability: « champion data » & « Comfort Zone » Performances… « Femtosecond part »: Reliability: « champion data » & « Comfort Zone » How far are the warranted performances from the « limits » : safety margin (level of pumping, extraction of the amplifiers, compressor efficiency ..) How high is the stress applied on optical components versus Damage Threshold: Fluence: 1J/cm²/face on Ti:Sapphire crystal Intensity on gratings : <100 mJ/ cm² 5

Pulse duration…: ultra short (<25fs) Contrast ratio…: ns, ps, ASE Performances… « Femtosecond part »: In a PW laser chain we have to deal with challenging performances like : Pulse duration…: ultra short (<25fs) Contrast ratio…: ns, ps, ASE Energy…: parasitic lasing Strehl ratio: intensity Stability: shot to shot, long term, pulse duration, pointing… 6

Gain narrowing control Our solution to warranty an ultrashort pulse duration on the long term :Acousto-Optic Programmable Gain Control Filter (Mazzler) Ti:Sa Pockels cell Spectral filter Acousto-Optic Programmable Gain Control Filter (AOPGCF) acoustic wave non-diffracted beam diffracted beam Mazzler Regenerative amplifier M.P. amplifier 1 M.P. amplifier 2 M.P. amplifier N Mazzler Spectrometer 7

Gain narrowing control 85 nm 30nm 8

Contrast ratio Contrast ratio The optimum contrast ratio (ASE, ns = replica, ps) is obtained through a combination of techniques. Laser architecture: design of the amplifier chain Keeping the pulse spectrum as large as possible (Mazzler) Cleaning Techniques (mJ level). Double CPA configuration Commercial product: SEQUOIA 9

Measurement performed with a modified SEQUOIA (10^15 noise level) Contrast ratio double CPA Contrast Characterization SUPERBOOSTER 10^14 ASE contrast Patented front-end SA + XPW Detection limit Measurement performed with a modified SEQUOIA (10^15 noise level) 10

Transverse lasing Numerical simulation for twin amplifier configuration: Pump energy : 80 J / Crystal Diameter crystal : 12 cm Crystal length : 3 cm Absorption : 90% 11

Double amplifier "standard" Transverse lasing Comparison of different amplifier configurations :   Pump energy Pump density Transverse Gain Single amplifier 160 J 2 J/cm2 400 Double amplifier "standard" ampli 1 100 ampli 2 200 Double amplifier “Amplitude Technologies” (patented) 1,6 J/cm2 40 12

The pump lasers…the « black box-turn key » part in a PW laser chain… … must supply green ressources in reliable and cost effective conditions (« ownership cost ») 13

Pump lasers… Our approach for the pumping of the last amplifier is to keep always a large number of pumps to take advantages of the multiplexing : beam smoothing and improvement of the stability. We consider that 10 pump lasers for pumping one crystal is « comfortable » In case of failure of one pump laser the reduction of the laser performances is less than 5%… 14

Energy stability : Pump lasers mixing Measurement of energy over 500 shots. Input energy stability: 1,9 % RMS Input energy: 500 mJ For N=8 : Total pump energy: 15 Joules Output energy stability: 0,78% RMS Output energy : 5,2 Joules Experimental results

Amplitude Technologies Nd:YAG lasers Pump lasers… Amplitude Technologies Nd:YAG lasers TITAN series (up to 10J @ 5Hz) for the PW laser systems - Propulse series (up to 2.5J @10Hz) for the 100 TW- systems Amplitude Technologies Nd: YAG laser are all based on the same design. The TITAN series is an upgrades of the PROPULSE series to satisfy the need of PW-class amplifiers

Our performances in pump lasers Highest wall-plug efficiency >1.5%: only 12 flashs for > 10 J output @ 532 nm Lowest price per Joule in the Green High reliability (>40Mshots before flashlamp replacement) Excellent shot to shot stability (<0,9% RMS 5 Hz, <1,1% rms single shot operation) Accumulated experience (>100 multi Joule lasers produced and delivered)

Beam Quality 1%RMS

Pulse to Pulse Stability Pump lasers… Pulse to Pulse Stability 1%RMS Stability energy over 9 hours – 5Hz 100 000 shots measured. -0,9% RMS 19

Conclusion… The key points in Amplitude approach to high energy system are performances and reliability leading to customer’s satisfaction The proposed systems allow a full control of the laser parameters: control for ensuring operation and safety Excellence comes from a good balance between the warranted performances on the short term and the expected performances on the long term High Rep. Rate 100 TW-PW lasers lead to long term partnership between the supplier and the customer… the long term vision of the supplier is a crucial parameter in customer’s decision