Post on 19-Jan-2016
description
LSC meeting at LHO, March 2006 1LIGO- G060127-00-R
Results of 40m prototype
LSC meeting at LHOMarch 21, 2006
Osamu Miyakawa, Caltech
Robert Ward, Rana Adhikari, Matthew Evans, Benjamin Abbott, Rolf Bork, Daniel Busby, Hartmut Grote, Jay Heefner, Alexander Ivanov, Seiji Kawamura, Michael Smith, Robert Taylor, Monica
Varvella, Stephen Vass, and Alan Weinstein
LSC meeting at LHO, March 2006 2LIGO- G060127-00-R
Caltech 40 meter prototype interferometer
We succeeded in lockinga suspended-mass detuned RSE interferometer
with power recycling.
BSPRM SRM
X arm
Darkport
Brightport
Y armPrototyping will yield crucial information about how to build and
run AdLIGO.
Arm cavity finesse at 40m chosen to be = to AdvLIGO ( = 1235 )
» Storage time is x100 shorter. 33/166 MHz Control RF sidebands LIGO-I 10-watt laser, negligible thermal
effects» 180W laser will be used in
AdvLIGO. LIGO-I single pendulum suspensions
LSC meeting at LHO, March 2006 3LIGO- G060127-00-R
101
102
103
104
10-22
10-21
10-20
10-19
10-18
10-17
f [Hz]
h(f
) [1
/ Hz1/
2 ]
Suspension Thermal
Test Mass Internal ThermalResidual Gas
Seism
ic
quantum
Total noise
40 Meter Strain Sensitivity
AdLIGO vs. 40m noise curve
101
102
103
10-24
10-23
10-22
10-21
Frequency [Hz]
Stra
in [1
/ H
z]
Quantum noiseSeismic noise
Suspension thermal noise
Silica Brownian thermal noise
Coating Brownian noise (1/f)
Gravity GradientsTotal noise
Fight the Fundamental Noise Sources:
1) Seismic2) Thermal3) Quantum
Not very likely that we’ll actually detect any gravitational waves here,but hopefully we’ll learn some things about operating interferometers, especially about the quantum noise.
LSC meeting at LHO, March 2006 4LIGO- G060127-00-R
130
150
170
190
210
Mag
(dB
)
100
101
102
103
104
105
-180
-90
0
90
180
Frequency (Hz)
Pha
se (
deg)
40m DARM Optical Response
The 40m operates in a
detuned RSE configuration, which gives rise to two peaks in the DARM transfer function:
1) Optical Resonance2) Optical Spring
UGF
LSC meeting at LHO, March 2006 5LIGO- G060127-00-R
101
102
103
104
370
380
390
400
410
420
430
440
dB
mag (
arb
units
)
40m DARM Optical Response
101
102
103
104
-200
-100
0
100
200
f (Hz)
Phase
(deg)
B&CData
DARM Optical response with fit to A.Buonanno & Y.Chen formula
DARM_in1 / DARM_out--------------------------------XARM_in1 / XARM_out
times arm cavity pole.
Yields optical response, taking out pendulum, analog & digital filtering, etc.
Optical spring and optical resonance of detuned RSE
were measured and fitted to ABYC formula.
Description of data, fit: P060007-00-R.http://www.ligo.caltech.edu/~cit40m/Docs/40mTF_060207.pdf
LSC meeting at LHO, March 2006 6LIGO- G060127-00-R
The way to full RSE
Carrier33MHz166MHz
Oct. 2004Oct. 2004Detuned dualrecycled Michelson
Nov. 2004Nov. 20045 DOF lock with offset in CARM
Oct. 2005Oct. 2005RSE
ITMy
ITMxBSPRM
SRM
ETMx
ETMy
Shutter
Shutter
ReducingCARM offset
LSC meeting at LHO, March 2006 7LIGO- G060127-00-R
CARM optical resonanceand Dynamic compensative filter
Optical gain of CARMOpen loop TF of CARM• Optical gain (normalized by transmitted power) shows moving peaks due to reducing CARM offset.
• We have a dynamic compensative filter having an exactly the same shape as optical gain except for upside down.
• Open loop transfer function has no phase delay in all CARM offset.
LSC meeting at LHO, March 2006 8LIGO- G060127-00-R
Residual displacement noise on arm
Avg=32/Bin=2L BW=0.374994
Frequency (Hz)1 10 210 310
Frequency (Hz)1 10 210 310
)1
/2M
agnit
ude (
m/H
z
-1510
-1410
-1310
-1210
-1110
-1010
-910
T0=07/09/2005 16:59:00Avg=32/Bin=2L BW=0.374994
C1:LSC-XARM_IN1(RMS)(REF2)
Requirement of RMS noise for full lock(10% of FWHM of RSE)
•RMS residual displacement noise was 30 times larger than the requirement.
Requirement of RMS noise for offset lock(10% of FWHM of offset lock on CARM)
LSC meeting at LHO, March 2006 9LIGO- G060127-00-R
CARM optical springs
102
103
80
90
100
110
120
130
140CARM optical springs at different CARM offsets
f (Hz)
CA
RM
opt
ical
res
pons
e (d
B)
Arm power = 6
Arm power = 8Arm power = 10•Solid lines are from TCST
•Stars are 40m data•Max Arm Power is ~80
LSC meeting at LHO, March 2006 10LIGO- G060127-00-R
Loss control for high finesse cavity
Design Measured(estimated)
Loss in each mirror 35ppm 100ppm
Cavity reflectivity 93% 85%(X arm 84%, Yarm 86%)
PRM reflectivity 93% 92.2%
Loss in PRC 0% 2.3%
Achievable PRG 14.5 5.0
Coupling of PRC Over coupled Under coupled
Input power 0.1W 1W
Power in one arm 560W 1900W
Optical spring 23Hz 41Hz
LSC meeting at LHO, March 2006 11LIGO- G060127-00-R
The DARM anti-spring
With SRM detuned in the wrong direction, will see an anti-spring in DARM
This is equivalent to resonating the –f2 RF sideband in SRC.
Oddly, this is also easier to lock
True for both full IFO and just the DRMI (though less noticeable on DRMI)
380
400
420
dB
ma
g (
arb
un
its)
40m DARM Optical Response
101
102
103
104
-180
-90
0
90
180
f (Hz)
Ph
ase
(d
eg
)
B&C
Data
Why is the correct SRM position harder to lock?
LSC meeting at LHO, March 2006 12LIGO- G060127-00-R
Mode healing/injuring at Dark Port
Negative spring constant with optical spring Positive spring constant
with anti spring
• Repeatable• The same alignment quality
Carrier power at DP is 10x smaller
LSC meeting at LHO, March 2006 13LIGO- G060127-00-R
Changing the DARM quadrature
•Squares are data, solid lines are from Optickle.
•Optickle results are generated by measuring response in a single quadrature while changing the CARM offset.
•This should be analogous to how the data was taken (reducing the CARM offset while always measuring with the same RF demod phase).
LSC meeting at LHO, March 2006 14LIGO- G060127-00-R
Calibration for DARM loop
D C S
P pendulum
DARM Cavityresponse
Sensing
A Actuator
F
Feedback filter
DARM_IN1: error signal
DARM_OUT: Feedback signal
N G
N
1
DCSFAPG
G
DCSN
1
G
APGN
G
DCSFN
1
/
1
G
GN
1
DARM_IN2
EXC
Use DARM_IN1
•Measure DARM_IN2/EXC=
•Estimate) S•Mesure (or estimate) C
Use DARM_OUT
•Measure DARM_IN1/EXC=
•Estimate A•Estimate P
G1
1
G
G
1
LSC meeting at LHO, March 2006 15LIGO- G060127-00-R
We succeeded in locking 5DOF of detuned RSE interferometer. We measured optical resonance and optical spring fitted to ABYC
formula.
Loss control is necessary in order to get proper power recycling gain with high (~1500) finesse cavity.
Lock should be acquired with low input power lock, then increasing power to avoid phase delay due to optical spring in DARM and also CARM loop.
Using analog common mode servo at very first stage to avoid less phase margin on CARM loop.
Higher UGF for DARM (~600Hz?) with faster digital system. Development of a new calibration method for observation. Using lower RF for WFS.
Summary of 40m workand suggestions for AdLIGO
LSC meeting at LHO, March 2006 16LIGO- G060127-00-R
Next steps Stable operation and noise hunting More lock acquisition schemes Modeling/E2E simulation for AdLIGO DC readout with Output Mode Cleaner Squeezed Vacuum in the Dark Port Active Alignment control with wave front sensors LF RF modulation scheme Alternatives to Mach-Zender Cleaning mirrors Narrow-band operation
SQL interferometer using lighter mirror?
LSC meeting at LHO, March 2006 17LIGO- G060127-00-R
Optical noise of 40m in E2E
• Simple length control (UGF~100Hz)
• Err2/(Err1/DARM) DARM: DARM excitation on mirrorsErr1: error signal with DARM
excitationErr2: error signal with optical noise
• How much further does E2E need to go? 2-photon?
• input vacuum?• Quantum control?• Or just classical physics +
shot noise + radiation pressure noise ?
Err2/(Err1/DARM)
LSC meeting at LHO, March 2006 18LIGO- G060127-00-R
a :input vacuumb :output fieldM2: C11C22-C12C21
h :gravitational wave
Measurement of optical response: ratio h and b
hSQL:standard quantum limit: transmissivity of SRM: input power coupling: GW sideband phase shift in IFO
a<<h; non-quantum measurement
Mathematical description foroptical spring in detuned RSE
SQL2
1
2
1
2221
12112
2
1 2 1
h
h
D
De
a
a
CC
CCe
Mb
b ii
ieM
DD
hh
b
cossin 2 21
SQL
a b
arm cavity
arm
ca
vity
laser
Signal recyclingmirror
Beam
splitt
er
h
h
ABYC equation:relation among input vacuum a , output field b, input power and gravitational wave h
i
n eDD
CCCChh
cossin
cos)(sin)(
2)(
21
22121
22211SQL
22
21212
2211 cos)(sin)( ieM
CCCC
a
b
Strain sensitivity: ratio h and a on b
Optical noise: ratio between a and b
LSC meeting at LHO, March 2006 19LIGO- G060127-00-R
Next steps Stable operation and noise hunting More lock acquisition schemes Modeling/E2E simulation for AdLIGO DC readout with Output Mode Cleaner Squeezed Vacuum in the Dark Port Active Alignment control with wave front sensors LF RF modulation scheme Alternatives to Mach-Zender Cleaning mirrors Narrow-band operation
SQL interferometer using lighter mirror?
LSC meeting at LHO, March 2006 20LIGO- G060127-00-R
Output mode cleaner, DC PD
OMC:Monolithic, copper, 4-mirror design.
DCPD:Monolithic, electronics invacuum nipple
LSC meeting at LHO, March 2006 21LIGO- G060127-00-R
Next steps Stable operation and noise hunting More lock acquisition schemes Modeling/E2E simulation for AdLIGO DC readout with Output Mode Cleaner Squeezed Vacuum in the Dark Port Active Alignment control with wave front sensors LF RF modulation scheme Alternatives to Mach-Zender Cleaning mirrors Narrow-band operation
SQL interferometer using lighter mirror?
LSC meeting at LHO, March 2006 22LIGO- G060127-00-R
Squeezing Tests at the 40m Audio frequency squeezed
sources now available at MIT Time to take steps toward
eventual implementation on long baseline interferometers
» Homodyne detection along with ifo signals and noise couplings
– Most interesting and relevant for complex ifo configurations
» A few interferometer configurations possible
– narrow- or broadband RSE, DRMI, FPMI
» Noise coupling studies possible» LIGO-like control systems for eventually
porting squeezing technology to long baseline ifos
1kHz 10kHz 100kHz
1
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