Transcript Timing Sync

Summary Timing and Diagnostics
1Franz
X. Kärtner and 2Steve Jamison
1CFEL - DESY and MIT, 2Daresbury
CW / Pulsed Timing Distribution and Synch.
MIT- DESY Pulsed
LBNL Cw- Laser
Timing Stabilized Optical Fiber Links
fs x-ray
pulses
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Pulsed Timing-Stabilized Fiber Links
PZT-based fiber
stretcher
Mode-locked laser
Fiber link ~ several
hundreds of meters
to a few kilometers
isolator
Balanced Optical
Cross Correlator
Faraday
rotating
mirror
Cancel fiber length fluctuations slower than the pulse travel time (2nL/c).
1 km fiber: travel time = 10 μs  ~100 kHz BW
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Other Implementations
Pulsed
CW
FLASH @ DESY
European XFEL planing
PAL in prototype phase
LCLS @ SLAC
XPS @ APS
NGLS planing
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FERMI CW Transmitter
Electron bunch arrival time measurement
Drive KLY3 unstable
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5.3fsRMS in 10 days
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Towards sub-fs systems
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Jungwon Kim, KAIST: Sub-100 attosecond Ultrafast Lasers
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Ti:sapphire Laser Jitter ~ 13 as
A. Benedick, et al. Nat. Photonics 6, 97-100, 2012
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Timing To Do List

Ongoing work is concentrated on pushing the timing precision towards
the sub-fs scale in laboratory experiments

Urgent need in engineered implementation of sub-10fs systems in
accelerator laboratories with many > 10’s of links.
- systematically eliminate free space sections and components
- all fiber implementations avoiding unintended reflections
- integrated optical components, plug and play
- develop a true timing technology base suited for modulator
implementations in accelerator facilities
 Open issues for sub-systems operating at low-repetition rate:
characterize drifts of amplifiers and how to compensate for it
characterize intra pulse train drifts and how to compensate for it
 Ultimately single shot X-ray – optical cross correlator to eliminate
critical drifts at the output
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Diagnostics – longitudinal profile
Bernhard Schmidt, DESY
Measured Spectrum -> temporal profile.
Retrieval of missing phase info through Kramers-Kronig
Much discussion on feasibility of retrieval
- Sceptics converted by real data demonstration
- only possible through thorough calibration
- ..caveats/pitfalls & puzzles still remain
Discrepancies:
real beam effects (?)
Online bunch profile available for FLASH operators....
Prospects of EO as “facility ready” systems...?
Current time resolution ~1 ps
potential improvement to 100fs (state of art) with data deconvolution..
Do we need explicit time information...?
Upconvert bunch form factor to an optical spectrum
Potential for robust all-optical diagnostic - simple/robust ns laser
Discussion on whether the phase information could be experimentally retrieved.
Yes, probably ...
With reintroduction of modest complexity (another laser!)
Time explicit diagnostics
Many challenges need to be overcome together to break the
100fs “barrier” in resolution
-Materials issues
-Bandwidth currently ~ 10THz. Want ~50THz bandwidth!
-Potential solutions in new materials, or in multi-crystal detectors
- optical characterisation issues
- FROG concepts for sub (optical) pulse
duration characterisation
- phase retrieval at low pulse energy..
- splicing of multi-crystal detectors
Wider diagnostic challenges
(no claim to be comprehensive!)
High dynamic range imaging
- “halo” & high current machines.
- high repetition rate laser wire as potential solution
Ultrafast Photon diagnostics (arrival / duration)
- (soft-xray ) – attosecond laser technique; other?
- hard xray . Via electron beam diagnostics (energy loss). Other?
Laser-plasma diagnostics – almost everything challenging!
- ~1 fs duration
- Emmittance
- Energy spread
- slice parameters !!!?
But some nice results coming out (duration through faraday effect in plasma)
Users and operator availability vs. “Diagnostics-by experiment”
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Summary Timing and Diagnostics
Thank you to speakers
and workshop organizers