XFEL 2004 at SLACm. ferianis

1
Synchronization and phase monitoring recent
results at ELETTRA

• Synchronization experiment using light sources
  currently available at Elettra
• Streak camera measurements
• CW Phase measurements
• Status of the light-to-light jitter monitor
• Single event phase measurement

Mario Ferianis, Miltcho Danailov SINCROTRONE
TRIESTE, Italy
2
Radiation sources currently available at Elettra

• Sources presently available at ELETTRA
• Bending Magnet S12.2 (diagnostic beam line)
• tFWHM30ps tREP ? 1MHz
• Storage Ring - FEL
• tFWHM8ps tREP ? 4MHz,
• Table top fs-lasers TiSa and CrLiSaf
• tFWHM?110fs tREP ? 100MHz
• The SR-FEL is naturally synchronized to ELETTRA
• The table-top lasers may be locked to an external
  RF

3
Synchronization experiment of a fs Laser to
Elettra Sources
Power Splitter
fREF 83.2756MHz
Phase Detector
Power Splitter
Reference IN
Laser IN
Laser Timing Stabilizer
fREP283.2756MHz
LP filter
Piezo driver
Laser cavity
Piezo actuator
4
View of the Profile Monitor laboratory with the
CrLiSAF laser and the Streak Camera
5
Streak Camera acquisitionMulti Bunch (2ns
spacing) beamlaser _at_99.93MHz
2ns
10ns
laser
fREP1fRF?5 99.9308MHz
6
4 Bunch beam (216ns/bunch) laser_at_83.275MHz
(12ns)
fREP2 fRF?6 83.2756MHz
7
5 accumulated acquisitions
Elettra 4 bunch beam
69ms
880ps
Laser phase oscillations due to external kick
180ps
8
All three sources
6.7ms
9
Phase Detector AD8302 (0?2.7GHz) Analog Devices?
Vector analyser on a chip
10
Vphase vs. frequency _at_100MHzDFtot100kHz ?
DFTOT0.135deg
DFtot0.135deg DFstep13.5mdeg
1deg_at_100MHz 27.7ps DTmin0.187ps (DTstep
/2) 1deg_at_3GHz 0.926ps DTmin6.25fs
DVSTEP0.135mV
11
Comparison of two phase measurements
RS generator
Spectrum Analyzer HP3589
1) V PHASE
AD 8302 Phase Detector
Digital Oscilloscope TEK 7104
A
Power Splitter
B
Reference IN
Laser IN
Ceramic Band Pass LC filter
Laser Timing Stabilizer
Power Splitter
2) Phase OUT
Photo diode
Laser cavity
Piezo driver
fREP283.2705MHz
Piezo actuator
12
Spectra of phase noise of the laser locked _at_
83.2705MHz
AD8302 Vphase
CLX 1100 Phase OUTPUT
13
Locked laser damping timeto an external kick
AD8302 Vphase 100mV/div
300ms
CLX phase OUT 20mV/div
14
Experiment set-up in the SRPM hutch
Power Splitter
fREF 83.2756MHz
Phase Detector
Power Splitter
Reference IN
Laser IN
Laser Timing Stabilizer
fREP283.2756MHz
LP filter
Piezo driver
Laser cavity
Piezo actuator
15
Bandpass filter response to 4 Bunch
beam,f083.275MHz, BW 6.5MHz.
16
AD8302 phase measurement 6.5MHz filter output
vs. reference (83.275MHz)
DV330mV ? 33deg
17
Narrowband (BW2.5MHz)bandpass filter
18
FERMI Phase Measurements

• The term Phase measurement generally refers to
  measuring the phase of a signal w.r.t. a
  reference.
• Rigorously, we can speak about phase when dealing
  with sinusoidal signals, eventually sinusoidal
  bursts.
• For FERMI applications, two different phase
  measurements are needed
• sinusoidal to reference (CW/CW burst measurement)
• pulse to reference (single event measurement)
• For pulsed signals, the phase difference can be
  defined as the time interval bewteen pulse
  arrival and next zero crossing of the reference
  signal.
• The most critical measurement is the second one
  due to
• required (sub-) ps resolution
• ultra short pulses of limited amplitude (low
  energy signals)
• low repetition rate (1 to 100Hz)

APL - Dip. Elettronica ed Informatica, Trieste
University and AllTEK Innovation s.r.l.
19
Proposed scheme for single event phase measurement
APL - Dip. Elettronica ed Informatica, Trieste
University and AllTEK Innovation
0 Xing detector (low jitter)
Beam pulse signal
Pulse stretcher
Hold off
Time interpolator (SiGe logic)
Reference signal
0 Xing detector (low jitter)
Pulse stretcher
Hold off
20
Zero X-ing detector prototypetests with Pulse
GeneratortPULSE300ps APULSE PK-PK90mV
fREP10kHz
21
Zero X-ing detector prototype tests _at_
fREP10Hzfs laser Pockels Cell 25GHz
Photodiode
22
Future work

• To complete direct light-to-light phase
  measurements in 4B mode
• Bending Magnet to external fs laser
• Bending Magnet to SR-FEL
• SR-FEL phase during Q-switch w.r.t. a non
  modulated RF (?)
• To complete jitter reduction work in the Profile
  Monitor hutch
• To implement phase measurement at low rep rate
• 10Hz i.e. FERMI
• To characterise laser jitter in fiber optic
  transmission
• To study the feasibiltiy of an in-house improved
  version of phase locking system (timing
  stabilizer)