Status of the Laser System Sparc Laser group A. Ghigo, G. Gatti, P.Musumeci, M. Petrarca, C. Vicario. C. Vicario SPARC review committee LNF 14/06/2005

sa Outlines  Report on the Dazzler experiment at BNL  Laser system description  Installation and tests of the SPARC laser system system  Conclusions C. Vicario SPARC review committee LNF 14/06/2005

Impulso gaussiano senza filtraggio Dazzler

Dazzler Filter for Square Pulse x 10 4 Wavelength (nm) Spectral intensity Blue UV IR

Spettro UV ottimizzato Conversione di armonica è molto sensibile a amp phase & amp modulation in IR. Modulazione 1% in IR >10% in UV FWHM UV è 1.94 nm Spettro modulazione minima 7% Blue edge 13%, red 17% del FWHM Il dazzler sembra non poter compensare queste mod così fini x 10 4 Wavelength (nm) Spectral intensity

Misure di cross-correlazione 100 fs IR ~10 ps UV BBO crystal 200 fs blue Power meter Delayed Misure su impulsi di 20 ps mostrano una perfetta sovrapposizione tra traccia di x-correlazione e spettro

10 ps cross-correlazione maggior peso degli ordini di fase superiori

Laser Laser parameters : Oscillator: 860mW, 790nm, 10nm BW Regen: 14.5mJ pump, 30 roundtrips, 1.45mJ output 2-pass amp: 269mJ pump, 34mJ output Compressor: 15.5mJ output Conversion: 6.2mJ input, 315uJ output, 5% efficiency. Input limitato da danneggiamento ottiche. Dazzler resolution: 0.3nm, ma nelle condizioni sperimentali è possibile correggere dettagli ~1.5nm

SDL layout 1.6 cell gun with copper cathode 70 MeV Bend 5 MeV Bend Dump RF zero phase screen UndulatorsLinac tanks 30 mJ, 10 nm Ti:Sapphire laser Triplet MeV zero phase linac

e-beam measurement Q=70 pC

e-beam temporal distribution Q=70 pC dopo ottimizzazione filtro

e-beam temporal distribution Q=300 pC

Misura distribuzione temporale e spettrale

UV streak camera e cross- correlation

Si sono effettuate misure preliminari di pC, 60 MeV L’emittanza trasversa diminuisce da 2 a 1.5 [μrad] passando da impulso gaussiano a quello flat top. Le misure di emittanza slice non sono consistenti. (>2.3 μrad). Le misure evidenziavano limiti di risoluzione dei BPM. Cambiamento lattice?? Servirebbe una analisi sistematica dei risultati.

5 ft 5050 Nd:YAG pump laser Harmoni cs 14 ft Laser top view 5 ft C. Vicario SPARC review committee LNF 14/06/2005

Nd:YAG pump laser Synchrolock Mira control HIDRA Laser/optical table (5 x 14 ft minimum) UV Stretcher Elevated support/stand (optional) Harmonic s SDG Evolution EVO controller EVO chiller Mira chiller Verdi controller Laser side view C. Vicario SPARC review committee LNF 14/06/2005

Picture of the oscillator and the pump C. Vicario SPARC review committee LNF 14/06/2005

Oscillator pump laser Main features  CW operation, multimode  5 W power  Frequency doubled YFL at nm  Diode pumped solid state laser (DPSS). Diodes are in the controller. Fiber coupled to the scillator laser head. C. Vicario SPARC review committee LNF 14/06/2005

Oscillator overview C. Vicario SPARC review committee LNF 14/06/2005 Main features  CW operation, at 79+1/3 Mhz  Output power 800 mW  Pulse duration >130 fs fwhm and bandwidth < 12 nm.  Tunability between nm.  Synchronization to an external generator or laser.

Synchronization measurements We tested the oscillator rep. rate with an external sinusoidal oscillator. At the coherent facility the synchronization jitter of two oscillators was measured. Synchrolock Off Synchrolock On C. Vicario SPARC review committee LNF 14/06/2005

Oscillator spectral and time domains measurements C. Vicario SPARC review committee LNF 14/06/2005 The spectrum and the pulse length are in the specs.

We first stretch the pulse in time so to lower its peak power. Then, we amplify it up to saturation, and finally we recompress the pulse width. t Short pulse oscillator t Dispersive delay line t stretch = J sat /I damage Ti:Al 2 O 3 ~ 200 ps tt Solid state amplifier Saturation is reached safely t Peak power increase proportional to t stretch > 1000 t Inverse delay line CPA CPA: principle of operation C. Vicario SPARC review committee LNF 14/06/2005

Hidra Amplifier Mira Seed Verdi VerdiPump Evolution Pump fs pulse, low energy <ps pulse, high energy Ti:Sa amplifier system: components CW Continuum Pump 2 ns pulses high energy C. Vicario SPARC review committee LNF 14/06/2005

Chirped pulse amplifier layout Multipass amplifier Stretcher Regen amplifier Pumps Compressor Seed C. Vicario SPARC review committee LNF 14/06/2005

Pictures of the amplifier Stretcher CompressorRegen. amp. Multipas amps C. Vicario SPARC review committee LNF 14/06/2005

The regenerative amplifier is a z-cavity oscillator with an input and an output gates From stretcher: SEED Output Ejector Pockel cell and reflective polarizer Ejector off Ejector on Injector Pockel cell and waveplete C. Vicario SPARC review committee LNF 14/06/2005

Amplifier’s pump lasers Regenerative pump laser  Diode-pumped, intra-cavity doubled, 1 kHz Q-switched, Nd:YLF lasers.  The laser is compact, reliable and it is fully controlled by the computer.  The output power is 15 W. Multipass pump laser  Lamp pump, amplified Nd:YAG. The amplified pulse is frequency doubled to obtain 532 nm.  The pulse energy achieves 720 mJ, with a length of 8 ns and a rep. rate of 10Hz C. Vicario SPARC review committee LNF 14/06/2005

Summary of the IR specs ParametersRequirementsMeasured Wavelength (output of Hidra-50)800 nm Repetition rate10 Hz Pulse energy at laser output (Hidra-50) > 50mJ50 mJ Pulse length< 120 fs FWHM104 fs FWHM Temporal pulse shape Gaussian~ Gaussian Beam divergence< 1.5 diffraction limitM 2 x : 1.9 M 2 y : 1.6 Contrast ratioPre-pulse: > 1000:1 Post-pulse: >100:1 Pre-pulse: > 3000:1 Post-pulse: >300:1 Energy jitter (in UV)< 5% rms IR beam profile~ TEMoo C. Vicario SPARC review committee LNF 14/06/2005

Amplified pulse measurements The autocorrelation profile (duration of 153 fs) indicates the pulse length is about 106 fs. IR profile at full energy: 55 mJ per pulse

UV stretcher The UV stretcher is used to change the UV pulse length between 0.5 ps to 12 ps. The measured efficiency is about 40%. Harmoni cs C. Vicario SPARC review committee LNF 14/06/2005

Energy 800 nm: < 5%

Third harmonic generator Two thin BBO crystals are used to generate the UV light. The fundamental and the second harmonic are mixed to produce the UV pulse. C. Vicario SPARC review committee LNF 14/06/2005

Second harmonic measurements C. Vicario SPARC review committee LNF 14/06/2005

Third harmonic measurements M 2 x : 2.7 M 2 y : 1.9 Beam profile at full energy Spectrum at full energy C. Vicario SPARC review committee LNF 14/06/2005

Summary of the UV specs ParametersRequirementsMeasured Wavelength nm266 nm Repetition rate10 Hz Pulse energy after harmonics unitN/A3.5 mJ Pulse energy at laser output (after UV stretcher) > 2mJ1.4 mJ Pulse length (tunable) ps FWHMN/A Temporal pulse shape GaussianN/A UV Bandwidth>10nm1.2 nm UV beam profile~TEMooSee pictures (two passes stretcher) Beam divergence< 1.5 diffraction limitM 2 x : 7.6* M 2 y : 2.9* Energy stability (in UV)< 5% rms< 4.5 % RF Timing jitter< 500 fs<350 fs C. Vicario SPARC review committee LNF 14/06/2005

Conclusion