krzysztof czuba ise, warszawa, [email protected] matthias felber
DESCRIPTION
Improved fiber-optic link for the phase reference distribution system for the TESLA technology based projects. Krzysztof Czuba ISE, Warszawa, [email protected] Matthias Felber DESY, Hamburg, [email protected]. OUTLINE. Design requirements System concept - PowerPoint PPT PresentationTRANSCRIPT
30.08.2005 SPIE, PA-IV Krzysztof Czuba 1
Improved fiber-optic link for the phase reference distribution system
for the TESLA technology based projects
Krzysztof CzubaISE, Warszawa, [email protected]
Matthias FelberDESY, Hamburg, [email protected]
30.08.2005 SPIE, PA-IV Krzysztof Czuba 2
OUTLINE
• Design requirements• System concept• First system version - summary• Improvements – second system
version• Measurement results
30.08.2005 SPIE, PA-IV Krzysztof Czuba 3
DESIGN REQUIREMENTS
Synchronize RF devices located along the accelerator with timing jitter (phase) error << 1 ps
Distribution distance:- 300 m UVFEL
- 3.1 km XFEL
- 15 km ILC
Distributed RF signal frequency range:
1 MHz to 2.856 GHz
1.3 GHz
30.08.2005 SPIE, PA-IV Krzysztof Czuba 4
LONG TERM PHASE DRIFTS
~ Target Device
Drifts caused mainly by temperature changes
Electrical / optical length change
Reason of drifts:
- In fiber: neff change
- In cable: physical dimension and dielectric properties change
RF signal source
1.3 GHz signal phase change in 5km of fiber. 10 oC temperature change
0
200
400
600
800
1000
1200
1400
1600
0 10 20 30 40 50 60 70 80 90 100
Time [min]
Ph
ase
chan
ge
[deg
]1400o @ 1.3 GHz corresponds to ~2800 ps!!
Feedback on phase required!!
30.08.2005 SPIE, PA-IV Krzysztof Czuba 5
SYSTEM CONCEPTPhase stable signal distribution over long distances (up to 20 km)
Feedback on phase suppressing long term drifts
Main application of this system is long term phase drifts monitoring / compensation
Circulator
Long LinkSimulator
Mirror
RF Phase Detector
DFBLaserFO Tx
FO RxA
Phase Shifter
Controller
DirectionalCoupler
FO RxB
RFSignal in
RF Phase Detector
5 km of single mode fiber in temperature controlled oven
Temperaturevariation
Error voltage
Output phase check
Test system block diagram
30.08.2005 SPIE, PA-IV Krzysztof Czuba 6
FIRST SYSTEM TEST IN A CLIMATE CHAMBER
FIRST EXPERIMENT
1.3 GHz signal source
Optical phase shifter (oven with 5km of fiber)
Long link simulator (oven with 20km of fiber)
RF phase detectors
DFB laser
F.O. receivers
F.O. components (circulator, coupler and other)
RF amplifiers
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0 2 4 6 8 10 12
time [h]
ph
as
e [
de
g]
Spool with fiber as a phase shifter
Problems with cabling, vibration and noise
Very slow phase shifter response
Closed loop - output signal phase
Obtained phase stability:
- Short term (1 min): 0.8 ps p-p- Long term : 5 ps p-p
System can cover very long distribution distances, up to 20km
30.08.2005 SPIE, PA-IV Krzysztof Czuba 7
SECOND SYSTEM VERSION - ODL
Motorized Optical Delay Line:
- Phase shift of 160o at 1.3 GHz – can cover distribution distances up to 500 m
-4.7 fs phase change resolution!
- Fast response – possible higher gains in the feedback loop
- Digitally controlled – no problems with noise and ambient temperature
- Much smaller than the spool inside of the oven
30.08.2005 SPIE, PA-IV Krzysztof Czuba 8
FIBER-OPTIC BOARD, SYSTEM CRATE
All components installed on soft foam base
Vibration problems removed
Easier to handle
Shorter connections, semi-rigid for RF signals
Improved power supply distribution
Shielding
System noise reduced significantly
30.08.2005 SPIE, PA-IV Krzysztof Czuba 9
NEW PHASE DETECTOR, CONTROLLER GUI
Very low sensitivity to ambient temperature changes: 0.01o/oC
Improved interface
New functionalities, e.g. automatic measurement data storage and labeling
Several important “bugs” removed
30.08.2005 SPIE, PA-IV Krzysztof Czuba 10
F.O. LINK V.2 – MEASUREMENT RESULTS
Measurement performed inside of the climate chamber
5 km of fiber used as long link
100 h measurement duration
ODL position followed temperature induced phase drifts
Output signal phase significantly more stable than in the first system version because of higher feedback loop gain and faster phase shifter
30.08.2005 SPIE, PA-IV Krzysztof Czuba 11
SUMMARY
Phase shifterShort term
stability [ps]Long term stability
[ps]
spool with fiber, 5km
0.8 5
ODL 0.3 0.8
Two system versions tested
Significant performance improvements obtained by use of the ODL and proper development of system hardware
Result comparison
Third system generation is under development. Phase shifter made of the ODL and a spool of fiber connected in series. This will allow to use advantages of both solutions