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Advanced LIGO optical configuration investigated in 40meter prototype LSC meeting at LLO Mar. 22, 2005 O. Miyakawa, Caltech and the 40m collaboration. Caltech 40 meter prototype interferometer. Objectives - PowerPoint PPT Presentation
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LSC meeting at LLO, March 2005 1LIGO- G050195-00-R
Advanced LIGO optical configuration
investigated in 40meter prototype
LSC meeting at LLOMar. 22, 2005
O. Miyakawa, Caltechand the 40m collaboration
LSC meeting at LLO, March 2005 2LIGO- G050195-00-R
Caltech 40 meter prototype interferometer
Objectives Develop lock acquisition procedure of detuned Resonant Sideband
Extraction (RSE) interferometer, as close as possible to Advanced LIGO optical design
BSPRM SRM
X arm
Darkport
Brightport
Y arm
Characterize noise mechanisms Verify optical spring and optical
resonance effects Develop DC readout scheme
Next Rob’s talk Extrapolate to AdLIGO via
simulation etc.
LSC meeting at LLO, March 2005 3LIGO- G050195-00-R
Important Milestones
20032003Installation of Four TMs and BS:doneLock of FP Michelson :done
20042004Installation of Power Recycling Mirror (PRM) ,Signal Recycling Mirror (SRM) :done Installation Mach-Zehnder to eliminate sideband of sideband :doneDRMI locked with carrier resonance using dither for Michelson DOF. :doneDRMI locked with sideband resonance using Double Demodulation(DDM) :doneOff-resonant lock of signal arm cavity with DRMI :doneOff-resonant lock of both arm cavities with DRMI :doneFull carrier resonant of single arm with DRMI :done
20052005Full RSE :in progress
Arm lock is really really difficult!Arm lock is really really difficult!
LSC meeting at LLO, March 2005 4LIGO- G050195-00-R
DRMI lock withUnbalanced sideband by detuned cavity
August 2004August 2004DRMI locked with carrier resonance (like GEO configuration)DRMI locked with carrier resonance (like GEO configuration)November 2004November 2004DRMI locked with sideband resonance (Carrier is anti resonant preparing for RSE.)DRMI locked with sideband resonance (Carrier is anti resonant preparing for RSE.)
Carrier
33MHz
Unbalanced166MHz
Belongs tonext carrier
Belongs tonext carrier
Carrier33MHz166MHz
ITMy
ITMxBS
PRM
SRM
OSA DDM PD
DDM PD
DDM PD
Lock acquisition After lock: MICH : dither @ 1200 Hz DDM@AP PRC : 33MHz@SP DDM@SP SRC : DDM@PO DDM@PO
Typical lock acquisition time : ~10secLongest lock:2.5hour
LSC meeting at LLO, March 2005 5LIGO- G050195-00-R
SP33,DDM,+/-33M,+/-166M@SP
DesignLockpoint
SP33Lockpoint0.56 degree (1.7nm)
+166resonant
+/-33 resonant
+/-33 off-resonant
LSC meeting at LLO, March 2005 6LIGO- G050195-00-R
40m Original design of SP DDM
DesignLockpoint
SP33Lockpoint0.56degree
+166resonance
+33resonance
0 50 100 150 200 250 300 3500
50
100
150
200
250
300
350
Demodulation Phase of f1
Dem
odul
atio
n P
hase
of f
2
Double Demodulation at SP-0.4
-0.4 -0.4
-0.4
-0.4
-0.3
-0.3
-0.3
-0.3
-0.3
-0.3 -0.3
-0.2
-0.2
-0.2
-0.2
-0.2-0.2
-0.2
-0.2
-0.1
-0.1
-0.1
-0.1
-0.1
-0.1
-0.1
-0.1
0
00
0
00
00
00
0
0.1
0.1
0.10.1
0.10.1
0.1
0.1
0.1
0.1
0.2 0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.3
0.3
0.3
0.3
0.3
0.3
0.4
0.4
0.4
0.4
-0.04
-0.04
-0.04
-0.04
-0.03
-0.0
3
-0.03
-0.03
-0.0
3
-0.03
-0.02
-0.02
-0.0
2
-0.02
-0.02
-0.0
2
-0.02-0
.02
-0.0
1
-0.01
-0.01
-0.0
1
-0.01
-0.0
1
-0.01-0
.01
-0.01
0
0
0
0
0
0
0
0
0
0
0.01
0.010.
01
0.01
0.01
0.010.
01
0.01
0.01
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.03
0.03
0.03
0.03
0.03
0.03
0.04
0.04
0.04
0.04
-0.1 -0.1-0.1
-0.1
-0.05
-0.0
5
-0.05
-0.05
-0.05
-0.05
-0.050
0 0
0
0
0
0
0
0
0
0
0
0
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.1
0.1
0.1
0.1
dc=0l+l-ls
+33 : off-resonant-33 : off-resonant+166: resonant-166 : anti-resonant
• l+ and ls plot separated
• Difficult to find PRM position without carrier
LSC meeting at LLO, March 2005 7LIGO- G050195-00-R
Offset l+ +0.56 deg, ls +0.56 deg
DesignLockpoint
SP33Lockpoint0.56degree
+166resonance
+33resonance
0 50 100 150 200 250 300 3500
50
100
150
200
250
300
350
Demodulation Phase of f1
Dem
odul
atio
n P
hase
of f
2
Double Demodulation at SP
-0.3
-0.3
-0.3
-0.3
-0.2
-0.2
-0.2
-0.2
-0.2
-0.2
-0.1-0
.1-0.1
-0.1
-0.1
-0.1
-0.1
-0.1
0 0
0
0
0
0
0
0
00
0
0
0.1
0.1
0.1
0.1
0.1
0.1
0.1 0.1
0.2
0.2
0.2
0.2
0.2 0.2
0.3
0.3
0.3
0.3
-0.06
-0.06
-0.06
-0.04
-0.0
4
-0.0
4
-0.04
-0.04
-0.0
4
-0.04-0
.02
-0.02
-0.02
-0.0
2
-0.02
-0.02
-0.0
2
-0.02
-0.0
2
0
0
0
0
0
0
0
0
0
0
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.04
0.04
0.04
0.04
0.04
0.040.04
0.06
0.06
0.06
0.06
-0.1
-0.1
-0.05
-0.0
5
-0.05
-0.05
-0.05
-0.0
5
0
0
0
0
00
0
0
00
0
0
0.05
0.05
0.05
0.05
0.05
0.050.05
0.1
0.1
dc=0l+l-ls
+33 : resonant-33 : resonant+166: resonant-166 : anti-resonant
• l+ and ls plot overlapping
• DC line changed• Easy to find PRM
position using 33MHz resonance
• Like AdLIGO configuration
• Carrier would be off resonant
LSC meeting at LLO, March 2005 8LIGO- G050195-00-R
40m vs. Ad-LIGO
40m
Ad-LIGO
x6
x2
x3x1.5
x8x17
LSC meeting at LLO, March 2005 9LIGO- G050195-00-R
Struggling lock acquisition for Arms
Problems
1. Sideband resonance on arm cavities
2. Resonant point shift due to detuned SRC
3. 16kHz sampling rate is too slow for 40m.
4. Coupling between X arm and Y arm
LSC meeting at LLO, March 2005 10LIGO- G050195-00-R
Which is first ? DRMI lock or Arms lock?
ITMy
ITMxBSPRM
SRM
ETMx
ETMy
• Carrier flash does not matter because DRMI is locked by DDM (beat of sidebands).
• Sideband flash matters.• Can keep locking ~10sec with
lower gain.ITMy
ITMxBSPRM
SRM
ETMx
ETMy
Shutter
Shutter
ETMx
ITMy
ITMxBSPRM
SRM
ETMy
Sideband resonance
Shutter
Shutter
Carrier33MHz166MHz
ITMy
ITMxBSPRM
SRM
ETMx
ETMy
DRMI first
Arms first•PRFPMI : succeeded•RSE : not succeeded!
»Because of resonant point shift due to detuned SRC
Normalized byPRC power
DDM
LSC meeting at LLO, March 2005 11LIGO- G050195-00-R
Resonant point shift
6x10-2
5
4
3
2
1
0
Nor
mal
ized
tra
nsm
itted
pow
er a
s in
put
[W]
-0.4 -0.2 0.0 0.2 0.4
CARM (XARM) [10-9
m]
Full RSEDRMI + X arm
Resonant point shift • Resonant point shifts in single arm lock because of carrier phase change in detuned SRC
LSC meeting at LLO, March 2005 12LIGO- G050195-00-R
Digital sampling for 40m RSE configuration
1.0x10-1
0.8
0.6
0.4
0.2
0.0
Nor
mal
ized
pow
er a
s in
put[
W]
-0.4 -0.2 0.0 0.2 0.4
Mirror position [10-9
m]
Full RSEDigital sampling points
with 3x10-6
m@1Hz
Digital sampling with arm transmitted light for RSE• Due to large seismic
motion, 3x10-6m at 1Hz assumed here
• Due to very high combined finesse of arm and PRC ~18000.
• Night is about 10 times better but still not enough.
• Needs wider linear error signal.
» Normalization technique to widen linear range
» Slower mirror motion
LSC meeting at LLO, March 2005 13LIGO- G050195-00-R
Error signal is produced by transmitted light as
1. to avoid coupling through carrier in central part,
2. to widen linear range.
Off-resonant lock scheme for arm cavity
Off-resonantLock point
Resonant Lock
offsetpower dTransmitte
1
LSC meeting at LLO, March 2005 14LIGO- G050195-00-R
Off resonant Arm lock with DRMI
DRMI with single arm lockDRMI with single arm lock Not so difficultNot so difficult Last ~10 minLast ~10 min Lock acquisition time ~1 Lock acquisition time ~1
minmin Switched to POX/POY Switched to POX/POY
signal normalized by signal normalized by transmitted light transmitted light
Full carrier was stored in Full carrier was stored in each arm cavity separately.each arm cavity separately.
Both arms lock with DRMIBoth arms lock with DRMI Off-resonant carrier on arm Off-resonant carrier on arm
cavitiescavities Last < 1 minLast < 1 min Locked only 2 timesLocked only 2 times
Yarm lockXarm lock
Arm power
Error signal
Ideal lockpoint
Offset lockOffset lock
LSC meeting at LLO, March 2005 15LIGO- G050195-00-R
Coupling between Lx and Ly
Laser
ETMy
ETMx
ITMy
ITMxBSPRM
SRM
SPAP
PO
lx
ly
lsx
lsy
Lx
Ly
: L=( Lx Ly) / 2
: L= Lx Ly
: l=( lx ly) / 2
: l= lx ly
: ls=( lsx lsy) / 2
Port Dem. Freq.
Lx Ly l l l s
SP f1 1 9.4E-1 -1.2E-3 -1.3E-6 -2.3E-6
AP f2 9.4E-1 1 1.2E-8 1.3E-3 -1.7E-8
SP f1 f2 -1.7E-3 -3.0E-4 1 -3.2E-2 -1.0E-1
AP f1 f2 -6.2E-4 1.5E-3 7.5E-1 1 7.1E-2
PO f1 f2 3.6E-3 2.7E-3 4.6E-1 -2.3E-2 1
POX/POY lock
Common of arms(CARM)Differential of arms(DARM)Power recycling cavityMichelsonSignal recycling cavity
Port Dem. Freq.
L L l l l s
SP f1 1 -3.8E-9 -1.2E-3 -1.3E-6 -2.3E-6
AP f2 -4.8E-9 1 1.2E-8 1.3E-3 -1.7E-8
SP f1 f2 -1.7E-3 -3.0E-4 1 -3.2E-2 -1.0E-1
AP f1 f2 -6.2E-4 1.5E-3 7.5E-1 1 7.1E-2
PO f1 f2 3.6E-3 2.7E-3 4.6E-1 -2.3E-2 1
CARM/DARM lock
• Coupling is 94% when carrier is resonant.
» Off-resonant lock for arms
POX
POY
LSC meeting at LLO, March 2005 16LIGO- G050195-00-R
The way to RSE
DRMI lock first using DDM
Full RSE lock
Both arms lock with offsetusing transmitted light
Arm lock first with offsetusing transmitted light
Switch to POX/POYsignal with the offset
Reduce offset
Switch to CARM/DARMsignal with the offset
Resonantpoint shift
Coupling betweenLx and Ly
Clear samplingProblem and
linear range problem
LSC meeting at LLO, March 2005 17LIGO- G050195-00-R
Way from off-resonant lock to com/diff lock
Off-resonantLock point
+/-0.2nm10
-5
10-4
10-3
10-2
10-1
Nor
mal
ized
tra
nsm
itted
pow
er a
s in
put
[W]
-0.4 -0.2 0.0 0.2 0.4
CARM (XARM) [10-9
m]
Full RSEFPMI(PRC,SRC misaligned)
RSE vs FPMI
LSC meeting at LLO, March 2005 18LIGO- G050195-00-R
Normalized SP166 for CARM
Dem.phase accuracy~10degre for 166MHz~0.1degree for 33MHz
Off-resonantLock point
+/-0.2nm10
-5
10-4
10-3
10-2
10-1
No
rma
lized
tra
nsm
itte
d p
ow
er
as
inp
ut
[W]
-0.4 -0.2 0.0 0.2 0.4
CARM (XARM) [10-9
m]
-0.2
-0.1
0.0
0.1
0.2
Full RSEFPMI(PRC,SRC misaligned)Raw error signal of SP166SP166 normalized by (TrX + TrY)SP166 normalized by PRC power
Normarized SP166
LSC meeting at LLO, March 2005 19LIGO- G050195-00-R
e2e SIMULATION: 4Om/AdvLIGO package optical configuration
IFO Central partIFO with Arms
ETMY
ETMX
PRM
ITMX
SRM
ITMY
BS
LIGO- G050195-00-R
e2e SIMULATION: 4Om/AdvLIGO package
Example:DARM @ AP 166 MHz
TWIDDLE and E2E comparison
• E2E validation of DC fields comparing with TWIDDLE
results: good agreement !
• E2E transfer functions simulations (and comparison with TWIDDLE ones) of DOF at SP, AP and PO shaking the end mirrors with white noiseat different demodulation frequencies : (33,133,166,199) MHz
I signal
Q signal
TWIDDLE
E2E
TWIDDLE
E2E
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