Status of the Laser System Sparc Laser group

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

Outlines Report on the Dazzler experiment at BNL lØsa ØLaser system description ØInstallation and tests of the SPARC laser system ØConclusions C. Vicario SPARC review committee LNF 14/06/2005

Impulso gaussiano senza filtraggio Dazzler

x 10 Dazzler Filter for Square Pulse 3 4 Blue UV 2. 5 IR Spectral intensity 2 1. 5 1 0. 5 0 785 790 Wavelength (nm) 795 800

Spettro UV ottimizzato 4 l l l 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. 2. 5 Spectral intensity l 3 x 10 2 1. 5 1 0. 5 0 262 263 264 Wavelength (nm) 265

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

10 ps cross-correlazione maggior peso degli ordini di fase superiori cc 012205 Detector (m. V) 120 100 80 60 40 20 0 -5 0 Time (ps) 5

l Laser parameters: Oscillator: 860 m. W, 790 nm, 10 nm BW Regen: 14. 5 m. J pump, 30 roundtrips, 1. 45 m. J output 2 -pass amp: 269 m. J pump, 34 m. J output Compressor: 15. 5 m. J output Conversion: 6. 2 m. J input, 315 u. J output, 5% efficiency. Input limitato da danneggiamento ottiche. l Dazzler resolution: 0. 3 nm, ma nelle condizioni sperimentali è possibile correggere dettagli ~1. 5 nm

SDL layout Bend Undulators 70 Me. V Bend 70 -200 Me. V RF zero phase screen 1. 6 cell gun with copper cathode zero phase linac Triplet Linac tanks Triplet Dump 5 Me. V 30 m. J, 10 nm Ti: Sapphire laser

e-beam measurement Q=70 p. C

e-beam temporal distribution Q=70 p. C dopo ottimizzazione filtro

e-beam temporal distribution Q=300 p. C

Misura distribuzione temporale e spettrale

UV streak camera e crosscorrelation

Si sono effettuate misure preliminari di emittanza @300 p. C, 60 Me. V l. L’emittanza trasversa diminuisce da 2 a 1. 5 [μrad] passando da impulso gaussiano a quello flat top. l. Le misure di emittanza slice non sono consistenti. (>2. 3 μrad). l. Le misure evidenziavano limiti di risoluzione dei BPM. Cambiamento lattice? ? l. Servirebbe una analisi sistematica dei risultati.

Laser top view 14 ft Nd: YAG pump laser 5 ft Harmoni cs 50 5 ft C. Vicario SPARC review committee LNF 14/06/2005

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

General Connections Layout AC 115 V / 220 V 20 A / 10 A C. Vicario Ch. 1: RGA Cavity trace Trigger BWD Sync out delay HV 2 Out delay 1 Out delay 2 DC motor Computer Air IN Head IN OUT Water/Air connections Chiller U S B Remote motor control Hidra-50 Head Photodiode HV 1 BWD out HSD 2 Trigger in RF sync HV 2 HSD 1 Lamp OUT Trigger OUT HV 1 Trigger IN Flash lamp trigger IN Q-Switch trigger IN USB Sync out Head Evoluti Nd: YAG Pump Laser on Scope Nd: YAG pump laser chiller (part of Nd: YAG pump laser controller) SPARC review committee Air OUT Head Mira Remote control SDG Hidra timing box IN OUT Optical connections Verd i Evolution Nd: YAG Pump Laser Time control box Control box QSW sync out Mira control box Com. port control box 60 Hz Com. port Electrical connections Verd i 50 Hz / Tap water from facility: 2 GPM min, 40 psi. 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 C. Vicario § CW operation, multimode § 5 W power § Frequency doubled YFL at 532. 1 nm § Diode pumped solid state laser (DPSS). Diodes are in the controller. Fiber coupled to the scillator laser head. SPARC review committee LNF 14/06/2005

Oscillator overview Main features § CW operation, at 79+1/3 Mhz § Output power 800 m. W § Pulse duration >130 fs fwhm and bandwidth < 12 nm. § Tunability between 700 -900 nm. § Synchronization to an external generator or laser. C. Vicario SPARC review committee LNF 14/06/2005

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

CPA: CPA principle of operation 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. Short pulse oscillator t Dispersive delay line Dtstretch = Jsat/Idamage Ti: Al 2 O 3 ~ 200 ps t Solid state amplifier Peak power increase proportional to Dtstretch > 1000 t Saturation is reached safely C. Vicario Inverse delay line SPARC review committee LNF 14/06/2005 t

Ti: Sa amplifier system: components Pump 2 Continuum Pump 1 Evolution Pump Verdi ns pulses high energy CW Seed Amplifier Mira Hidra 100 fs pulse, low energy C. Vicario SPARC review committee <ps pulse, high energy LNF 14/06/2005

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

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

The regenerative amplifier is a z-cavity oscillator with an input and an output gates. Ejector Pockel cell and reflective polarizer From stretcher: SEED 39 Output 14 26 27 23 22 21 20 15 16 17 Ejector off 24 28 25 19 18 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 k. Hz § 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 m. J, with a length of 8 ns and a rep. rate of 10 Hz C. Vicario SPARC review committee LNF 14/06/2005

Summary of the IR specs Parameters Requirements Measured 800 nm 10 Hz > 50 m. J 50 m. J < 120 fs FWHM 104 fs FWHM Gaussian ~ Gaussian Beam divergence < 1. 5 diffraction limit M 2 x: 1. 9 M 2 y: 1. 6 Contrast ratio Pre-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 Wavelength (output of Hidra-50) Repetition rate Pulse energy at laser output (Hidra-50) Pulse length Temporal pulse shape C. Vicario SPARC review committee LNF 14/06/2005

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

UV stretcher The UV stretcher is used to change the UV pulse length between 0. 5 ps to 12 ps. l The measured efficiency is about 40%. l Harmoni cs C. Vicario SPARC review committee LNF 14/06/2005

Energy stability @ 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 Spectrum at full energy Beam profile at full energy M 2 x: 2. 7 M 2 y: 1. 9 C. Vicario SPARC review committee LNF 14/06/2005

C. Vicario SPARC review committee LNF 14/06/2005

Summary of the UV specs Parameters Requirements Measured 260 -280 nm 266 nm 10 Hz N/A 3. 5 m. J > 2 m. J 1. 4 m. J Pulse length (tunable) 0. 5 -12 ps FWHM N/A Temporal pulse shape Gaussian N/A >10 nm 1. 2 nm ~TEMoo See pictures (two passes stretcher) < 1. 5 diffraction limit M 2 x: 7. 6* M 2 y: 2. 9* < 5% rms < 4. 5 % < 500 fs <350 fs Wavelength Repetition rate Pulse energy after harmonics unit Pulse energy at laser output (after UV stretcher) UV Bandwidth UV beam profile Beam divergence Energy stability (in UV) RF Timing jitter C. Vicario SPARC review committee LNF 14/06/2005

Conclusion