installation, commissioning and operation of the master laser … · 5 09.03.2009, ictp, trieste,ii...

Patrick Geßler DESYII Timing & Synchronization Workshop, ICTP, Trieste 09.03.2009

Installation, Commissioning and Operation of the Master Laser Oscillator at FLASH

V. Arsov, B. Bayer, M. K. Bock, M. Felber, K. Hacker, F. Loehl, B. Lorbeer, F. Ludwig,K-H. Matthiesen, H. Schlarb, B. Schmidt, A. Winter, J. Zemella(Deutsches Elektronen-Synchrotron)

S. Schulz, L. Wissmann(Universität Hamburg)

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09.03.2009, ICTP, Trieste,II Timing & Synchronisation Workshop Patrick Geßler, DESY


Agenda

Overview of the Synchronization System at FLASH Requirements for the Master Laser Oscillator (MLO) 3 Generations of MLOs RF Lock to Master Oscillator Measurements Pitfalls Conclusion

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Overview of the Synchronization System

NarrowBand.

Direct/Interferometer

EOMs/Seeding

End-station

LaserMLO MO-RF

Laser pulse Arrival beam/laser DWC/Kly

A & φ cavity

Desired point-to-point stability ~ 10 fs

<5fs

Direct

Distribution

LO-RF

Optical link Optical link<5fs <5fs

Optical link

Other lasers

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MLO2

MLO1

Fiber linkstabilizationunits(max 14)

Free space opt.distribution-Switching unit-Invar base plate-Vibration isolated-16 outputs

Distr. With EDFA for each link-Special passivethermal stabilization-One output for MLO lock based on Sagnac loop at 1.3GHz

Final implementation design

B. Beyer

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BC3SASE-Undulators

BC2

RF gun

ACC 23

Diag.

ACC 456ACC 1 CDR

CDR LOLA

THz Laser

ISR

TEO

MO

• Backbone: beam based stabilization of arrival time• Conjunction with high precision synchronization of lasers • Synchronization of all timing critical devices ( ~ 14 incl. FLASHII)• Point-to-point synchronization ~ 10 fs rms (e- < 30 fs rms) • Permanent operation and long term stability /availability investigation

Laser buildingEO, HHG and ORS

BPMBAM

L2L

BAMBPM

BAM PP-laser

MLO

MLO

BAM

L2RFDWC

L2LSeed

Beam arrival monitorLaser to laser synchronizationDirect laser seedingHigh precision down converterLaser to RF conversion

ORS


ISR

L2L

L2L

L2L

L2RFDWC

L2L

BAMBAML2RF

DWC

Seed

Seed

Experiment sFLASH

Opt-Cross..12 FLASH2 FLASH II

Dist

ribut

ion

HHG

Photo-cathode Laser

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Requirements for the Master Laser Oscillator

Mode-Locked Erbium Doped Fiber Laser Pulse Duration <100fs (FWHM) Repetition Rate 216.66MHz Output Power >120mW Integrated Timing Jitter <10fs [10Hz – 40MHz] Amplitude Noise <2 x 10-4 [10Hz – 1MHz] Reliability / Redundancy

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1st Generation MLO (Breadboard Version)

Original design: J. Chen et. al., Opt. Lett. 32, 1566-1568 (2007)

F. Löhl

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2nd Generation MLO

F. Löhl

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2nd Generation MLO Temp. Stabilization

Controller included Variable Set point

Stable Ground Plate Distribution included RF Electronic included Motorized Wave Plates

F. Löhl

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3nd Generation MLO

A. Winter

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3rd Generation MLO

Compact Modular Parts Lower Costs Online Spectrometer

A. Winter

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MLO Included Features Overview

Modular Parts

Electrical Monitor Output

Optical Monitor Output

Motorized Translation Stage

RF Lock Electronic

Online Spectrometer

Motorized Wave Plates

Temperature Stabilization

Piezo

3rd Generation2nd Generation1st Generation

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RF Lock to Master Oscillator

M. Felber

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Measurements – Noise and Jitter

Integrated timing jitter:< 6 fs [10kHz – 40 MHz]

relative intensity noise:0.016 % [10 Hz – 1MHz]

F. Löhl

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Measurements – Spectrum and Pulse Shape (I)

For different Pump Laser Power Level Wave Plates optimized for maximum Output Power Similar Spectra / Shapes are Achievable

F. Löhl

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Measurements – Spectrum and Shape (II)

For different Wave Plate Settings Constant Pump Laser Power of around 890mW

F. Löhl

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Measurements – Autocorrelation

Different Wave Plate Settings Constant Pump Laser Power

Pulse Width: 60 – 90 fs [FWHM](depending on Configuration)

Different Output Power

F. Löhl

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Measurements – Amplitude Stabilization

Without Feedback With Feedback

J. Zemella

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Pitfalls

Piezo bends due to weight / torque Alignment Make every Parts removable from the top Have enough degrees of Freedom Make the Ground Plate thick / stable enough A Modular Design could cause alignment problems Put the Shutter not before the RF Lock Monitor Port

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Conclusion

The MLO has a strong influence on the complete system Wave plate and pump power settings influence the optical

spectrum A high precision diagnostic is needed to investigate the

impacts In contrast to stretched pulse lasers, to achieve mode-

locking wave plate settings have to be changed Different wave plate settings for minimum phase noise and

maximum output power Questionable whether two identical MLOs could be set up

such that switching has no impact

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Thanks for your attention

installation, commissioning and operation of the master laser … · 5 09.03.2009, ictp, trieste,ii...

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