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 >