LIGO-G1200980
aLIGO EOM at LLO and LHOAssembly/testing/installation
Volker Quetschke, Gregorio Tellez, Joseph Coleman,
Center for Gravitational Wave Astronomy& Department of Physics and Astronomy
The University of Texas at Brownsville
and the LIGO-UF group
Department of PhysicsUniversity of Florida
LIGO-G1200980
Assembly/testing/installation of the aLIGO phase modulators
aLIGO modulators follow the design of the eLIGO modulators, but were adjusted to follow aLIGO specifications:
Three electrode, wedged RTP crystal(rubidium titanyl phosphate - RbTiOPO4)– Wedged avoids cavity effects and reduces
amplitude modulation– RTP has low absorption, is capable to handle
200W exhibits a small thermal lens– Three electrodes on one crystal minimize the number of optical
surfaces (and the price)
15 mm 7 mm 15 mmPolarization Angle [degrees]
p 5.2
s 4.7
LIGO-G1200980
Assembly/tuning at UTB
Assemble modulators in clean environmentBuild and tune three simultaneous pi-network resonant circuits with 50 Ω input impedance.(9.1 / 24.1 / 45.5 MHz)
LIGO-G1200980
Test at UF
Finalize tuning at UFMeasure sidebandsTest high power compatibility
Frequency [MHz]
EOM-1: Number of turns per coil
EOM-1pi network shunt capacitance
EOM-2: Number of turns per coil
EOM-2 pi network shunt capacitance
9.1 108 820 pF 102 680 pF24.1 67 270 pF 68 270 pF45.5 31 210 pF 30 190 pF
Frequency [MHz]
EOM 1 EOM 2
9.1 0.325 0.38824.1 0.117 0.18445.5 0.310 0.299
Setup with 150W laser and realistic beam parameters to verify high-power compatibility
Sidebands measured with three 24 dBm signals simultaneouslydriving all threeelectrodes
LIGO-G1200980
Installation at LHO H2 12/2011
Was installed, but shortly after uninstalled and retuned for H1 frequencies
LIGO-G1200980
Installation at LLO 07/2011
L1 modulator install
LIGO-G1200980
Modulation depth for 24 dBm drive
8.5 8.6 8.7 8.8 8.9 9 9.1 9.2 9.3 9.4 9.5 9.6 9.70.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50M for 9.1 MHz
44.844.9 45 45.145.245.345.445.545.645.745.845.90.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50M for 45.5 MHz
23.4 23.5 23.6 23.7 23.8 23.9 24 24.1 24.2 24.3 24.40.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50M for 24.1 MHzSome re-tuning was
done 04/2012
https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=3027
LIGO-G1200980
RFAM vs. PM
RFAM measurements with 24dBm drive
https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=3034
Freq. PM RFAM RFAM/PM
45.3 0.15 6.2E-06 0.000041
9.18 0.39 3.9E-05 0.000100
24.0 0.09 1.0E-06 0.000012
LIGO-G1200980
Installation at LHO 08/2012 Modulation depth for 24 dBm drive
8.90 8.95 9.00 9.05 9.10 9.15 9.20 9.25 9.30 9.35 9.400.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50 M for 9.1MHz
45.1
045
.20
45.3
045
.40
45.5
045
.60
45.7
045
.80
45.9
046
.00
46.1
00.000.050.100.150.200.250.300.350.400.450.50 M for 45.5MHz
23.8
023
.85
23.9
023
.95
24.0
024
.05
24.1
024
.15
24.2
024
.25
24.3
00.000.050.100.150.200.250.300.350.400.450.50 M for 24.1MHz
https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=3693
LIGO-G1200980
RFAM vs. PM
All went well
https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=3695
Freq. PM RFAM RFAM/PM
45.5 0.31 5.5E-05 0.000177
9.1 0.39 9.13E-05 0.000234
24.1 0.14 3.17E-05 0.000226
LIGO-G1200980
What’s Next?
Re-tuning for LIGO India?
LIGO-G1200980
Modulation depth / RFAM LLO
LLO - Chris explanation:< https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=2901 >
PM vs freq:< https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=3027 >
AM at peak:< https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=3034 >
LHO - PM vs freq:< https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=3693 >
AM at peak:< https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=3695 >