DESIGN AND FIRST EXPERIENCE WITH THE FERMI SEED LASER

M. B. Danailov, A. Demidovich, R. Ivanov, I. Nikolov, P. Sigalotti, P.Cinquegrana

Sincrotrone-Trieste, Basovizza, Trieste

FEL’11 August 2011 M.Danailov 2

OUTLINE

FERMI SEED LASER REQUIREMENTS

OPTICAL SCHEME AND LAYOUT LASER

BEAM TRANSPORT AND INSERTION INTO FEL

LOCKING/SYNCHRONIZATION TO THE FERMI

MASTER OSCILLATOR

SUMMARY AND PLANS FOR FUTURE

UPGRADES

FEL’11 August 2011 M.Danailov 3

FERMI SEED LASER REQUIREMENTS

HGHG WORKS WELL!!!

FEL’11 August 2011 M.Danailov 4

FERMI SEED LASER REQUIREMENTS

HGHG SCHEME MAIN REQUESTED PARAMETERS:

UV peak power ≥ 100 MW

Wavelength Tuning range : 240-360 nm (initial request), 200-280 nm

(current)

Pulse duration (FWHM): 100 fs range, longer for the comissioning

phase

Pulse arrival timing jitter : <50 fs RMS

Pulse energy stability: <4% , goal <2%

Central wavelegth stability: 10-4

Beam dimention (1/e2 intensity): 0.8-1mm , possibly variable

High reliability and hands-free operation

Beam focus: 11.2 m from insertion window and about 20 m

from laser room

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TUNABLE SEED LASER

100fs

4-6 mJ

MIXER 3

WLG

Dt

OPA1

Dt

Dt OPA2

Dt MIXER 1

MIXER 2

OPA3

Dt

Dt

MIXER 4

Pump

Las 2 Multipass

Compr

Pump

Las 1

ML OSC

Stretcher

Reg Amp

Ti:Sapphire Amplifier

Optical Parametric Amplifier

FEL’11 August 2011 M.Danailov 6

FERMI SEED LASER TUNABILITY

190 200 210 220 230 240 250 260 270 280 290 300 310 320 330

1

2

4

6

8

20

40

60

80

200

SF-FH_Signal

205-225 nm

SF-SH-SF_Idle

205-225 nm

FH_Signal

270-395 nm

SH-SF_Idler

260-297.5 nm

Outp

ut

energ

y [J]

Wavelength [nm]

SH-SF_Signal

225-260 nm

FEL’11 August 2011 M.Danailov 7

FERMI SEED LASER TUNABILITY

190 200 210 220 230 240 250 260 270 2801

2

4

68

20

40

6080

200

400

600

FH_Ti:S

195 or 198 nm

SF-SH-SF_Idler-F_Ti:S

TH_Ti:S

260 nm

SF-TH_Signal-TH_Ti:S

SF_FH_Signal-F_Ti:S

SH-SF_Idler

Ou

tpu

t e

ne

rgy

[J]

Wavelength [nm]

SH-SF_Signal

Tuning curve after upgrade

FEL’11 August 2011 M.Danailov 8

STATUS: Fixed wavelength configuration in use until July 2011

Wavelength : 260-262 nm (manually tunable)

UV peak power ≥ 400 MW

Pulse duration (FWHM): 150-220 fs range

Energy per pulse >80 μJ , smoothly variable down to nJ level

Beam dimention (1/e2 intensity): 0.8 or 1 mm 1/e2 diameter at virtual

undulator

Tunable seed for next FERMI Run:

Wavelength : 235-260 nm

UV peak power ≥ 100 MW (>80 MW at 235 nm)

Pulse duration (FWHM): 180-200 fs range

Energy per pulse >20 μJ (>15 μJ at 235 nm), smoothly variable down to nJ

level

Beam dimention (1/e2 intensity): 1 mm 1/e2 diameter at virtual undulator

FERMI SEED LASER

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FERMI SEED LASER

1.2 1.3 1.4 1.5 1.6 1.7 1.8

0

10000

20000

30000

40000

50000

60000

70000

INT

EN

SIT

Y (

a.u

.)

TIME(ps)

FEL’11 August 2011 M.Danailov 10

FERMI SEED LASER

255 256 257 258

0

200

400

600

800

1000

1200

1400

1600

1800

INT

EN

SIT

Y (

a.u

.)

WAVELENGTH(nm)

FEL’11 August 2011 M.Danailov 11

SEED LASER OPTICAL TABLE LAYOUT

To locking

setup

Opt Table 1: main laser system

Opt Table 2 (to the left, not shown): locking setup,

future HHG laser

FEL’11 August 2011 M.Danailov 12

SEED LASER OPTICAL TABLE LAYOUT

To locking

setup

Opt Table 1: main laser system

Opt Table 2 (to the left, not shown): locking setup,

future HHG laser

FEL’11 August 2011 M.Danailov 13

Beam Transport and Seed Insertion

Breadboard

UV beam on the main laser table deviated by the mirror on piezo tip-tilt mount for fine steering

SL insertion breadboard FEL1 photo (left) and optical scheme (right)

Distance Laser Exit-Undulator >20 m , with 12-18 mirrors in beam path Laser beam position monitored on 7 CCD cameras

Beam steering : 2 kinematic mounts with steppers in IR and 1 piezo based tip-tilt in UV,

2 kinematic mounts with stepper motors on the insertion breadboard

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Beam Transport and Seed Insertion

Breadboard

UV beam on the main laser table deviated by the mirror on piezo tip-tilt mount for fine steering

SL insertion breadboard FEL1 photo (left) and optical scheme (right)

Distance Laser Exit-Undulator >20 m , with 12-18 mirrors in beam path Laser beam position monitored on 7 CCD cameras

Beam steering : 2 kinematic mounts with steppers in IR and 1 piezo based tip-tilt in UV,

2 kinematic mounts with stepper motors on the insertion breadboard

FEL’11 August 2011 M.Danailov 15

Beam Transport and Seed Insertion

Breadboard

UV beam on the main laser table deviated by the mirror on piezo tip-tilt mount for fine steering

SL insertion breadboard FEL1 photo (left) and optical scheme (right)

Distance Laser Exit-Undulator >20 m , with 12-18 mirrors in beam path Laser beam position monitored on 7 CCD cameras

Beam steering : 2 kinematic mounts with steppers in IR and 1 piezo based tip-tilt in UV,

2 kinematic mounts with stepper motors on the insertion breadboard

FEL’11 August 2011 M.Danailov 16

LOCKING&SYNCRONIZATION STATUS: since the beginning of last FERMI run the locking&synchronization

scheme developed at Elettra is fully operational, both with RF based (3 GHz harmonic) phase detection and with optical phase detection

FEL’11 August 2011 M.Danailov 17

LOCKING&SYNCRONIZATION

Long term (8 hours) performance of RF harmonic (left) based

and optical (right) phase detection

PP ~2.3 ps

RMS 400 fs PP ~0.3 ps

RMS 53 fs

Relative phase noise curve

Blue: RF locking, 54 fs 100 Hz-10 MHz

Red: optical locking, 51 fs 100 Hz-10 MHz

FEL’11 August 2011 M.Danailov 18

SUMMARY AND FUTURE WORKS

FERMI comissioning during last run confirmed that

HGHG seeding is valuable from both FEL physics and

user point of view

The Seed Laser met most requirements and has shown

good reliability

The Fixed Wavelength option might proove an

interesting option also for the future, allowing freedom for

more ‘exotic’ regimes

Further impovements of the FERMI seed system: -New version of the optics and seed insertion for FEL2

-Implementation of a beam quality measurement for the OPA based

UV seed (multiplexing several images on the same CCD)

-Roots towards improving OPA beam quality under consideration

-Feedaback on beam position on the virtual undulator

-Going to shorter wavelengths (Sub-200 nm seed, HHG based seed)

under study