eligo/advligo fi update
DESCRIPTION
eLIGO/advLIGO FI update. Antonio Lucianetti, K.L. Dooley, R. Martin, L. F. Williams, M.A. Arain, V. Quetschke, G. Mueller, D.B. Tanner, and D.H. Reitze University of Florida, Gainesville, FL. Ligo-Virgo Meeting, Hannover, Oct. 2007. G070675-00-R. ● High isolation ratio (>30 dB) - PowerPoint PPT PresentationTRANSCRIPT
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eLIGO/advLIGO FI updateeLIGO/advLIGO FI update
Antonio Lucianetti, K.L. Dooley, R. Martin, L. F. Williams,
M.A. Arain, V. Quetschke, G. Mueller, D.B. Tanner, and D.H. Reitze
University of Florida, Gainesville, FL
Ligo-Virgo Meeting, Hannover, Oct. 2007G070675-00-R
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FI for eLIGOFI for eLIGO
1
Laser Mod FI
GW readout
IMC
OMC
● High isolation ratio (>30 dB)● Low beam drift (< 100 rad)● Weak thermal lens (residual │f│> 30 m)
25 W
Current iLIGO FI at Livingstonprovides an isolation ratio aslow as 13.6 dB
Refl
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eLIGO/advLIGO FI eLIGO/advLIGO FI configurationconfiguration
2
● Faraday Rotator - Two 22.50 TGG crystals with a reciprocal 67.50 QR
● Calcite wedge polarizers (superior to TFPs)
● Thermal lens compensation with - dn/dT material (deuterated dihydrogen phosphate, or ‘DKDP’)
Q R
W P TG GTG G
D K D P
TFP
R E FL
IS O
C W P C W P
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Problems we have Problems we have encounteredencountered
TGG and DKDP crystals: - surface damage - improper AR
coatings
SOLUTION: New vendor (NG)
Magnet
Diameter ~ 200 m
3
FI magnet ring failure
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Characterization of Characterization of individual TGGsindividual TGGs
yf it = 2E-08x6 - 2E-06x5 + 6E-05x4 - 0.0003x3 - 0.0311x2 + 0.827x + 17.26
16
17
18
19
20
21
22
23
24
25
26
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50
TGG sleeve full turn [#]
TG
G r
ota
tio
n a
ng
le [
deg
]
●Incident laser power: 1 W
Result from 6th order polynomial fit:
Max TGG rotation angle (crystal #2): 24.03 deg +/- 0.01 deg
4
z
z
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Thermal lens created Thermal lens created by TGG and DKDPby TGG and DKDP
Telescope
Fiber laser beam(1-30 W)
DKDP or TGG
Focusing lens
Beam Scan
Thermal Lensing in 'x-direction'
-200-150-100
-500
50100150200
0 10 20 30 40
Power (W)
Fo
ca
Le
ng
th (
m)
TGG (Air)
DKDP (Air)
5
Thermal Lensing in 'y-direction'
-200-150-100-50
050
100150200
0 10 20 30 40
Power (W)
Fo
cal
Len
gth
(m
)
TGG (Air)
DKDP (Air)
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COMSOL Simulation COMSOL Simulation (radiation enabled on faces and (radiation enabled on faces and
edges)edges)
30 W incident powerTime from t = 0s to t = 60s with a line every 1s
Parameters: TGG radius = 10.3 mmLaser beam radius = 1.5 mm
Temperature in the center of the pumped face (point [0,0,0])
6
The time constants of thermal lensing are in the order of seconds
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30 W incident powerTime from t = 0s to t = 3600s (60min) with a line every 60s (1min)
Parameters: TGG radius = 10.3 mmLaser beam radius = 1.5 mm
Temperature in the center of the pumped face (point [0,0,0])7
COMSOL Simulation COMSOL Simulation (radiation enabled on faces and (radiation enabled on faces and
edges)edges)
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Faraday Isolator Faraday Isolator performance Isolation performance Isolation
ratio (CWPs)ratio (CWPs)
8
0
5
10
15
20
25
30
35
40
45
50
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Time [min]
IR [
dB
]
DKDP between CWPs
DKDP after CWPs
● Decrease in isolation ratio under vacuum as time went on ● Could be recovered by < 2 degree rotation of waveplate
PL = 25Wp = 4*10-6 Torr
WP adjusted
IR of iLIGO FI (LLO)
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Faraday isolator Faraday isolator performance Effect of performance Effect of
vacuum vacuum
9
● PL = 25 W
● DKDP between CWPs
0
5
10
15
20
25
30
35
40
45
0 50 100 150 200
Time [min]
IR [
dB
]
in vacuum (p = 4*10^-6 Torr)
in air with chamber windows (p = 760 Torr)
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Faraday isolator Faraday isolator performance thermal performance thermal
drift (CWPs)drift (CWPs)
PL = 25Wp = 4*10-6 Torr
Result:Over the course of six hrs the horizontal and thevertical intrinsic drifts are < 50 microradians
FI
Refl beam thermal drift intrinsic to FI
-200
-150
-100
-50
0
50
100
150
0 100 200 300 400 500 600
time [min]
dri
ft [
mic
rora
dia
n]
horizontalvertical
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ELIGO FI ScheduleELIGO FI Schedule
LLO● Assembly, final test and measurements of the FI will be done in the clean optics lab at the LIGO Livingston Observatory ● Installation of the FI for LLO will start on Nov 13, 2007.● Integration and commissioning of the FI and Input Optics with PSL is planned to start on June 3, 2008.
LHO● Installation of the FI at LHO is planned to start in December 2007 or January 2008.● Integration and commissioning of the FI and Input Optics with PSL is planned to start on Feb. 19, 2008.
11
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ConclusionsConclusions
● Initial LIGO FI measurements reveal that isolation requirements for E-LIGO are very relaxed
→ 20 dB will work well ● Obtained 43 dB isolation ratio with CWPs in vacuum Decrease in isolation ratio under vacuum should be recovered by < 2 degree rotation of waveplate. Intrinsic thermal drift of the reflected beam was < 50 microradians for the horizontal and vertical axes
● Performance is expected to improve with Northrop Grumman crystals (TGG/DKDP) and new precision mount for DKDP with tip/tilt positioning