Aspen 2004 1LIGO-G040039-02-R

Current Status ofthe 40m Detuned RSE Prototype

Seiji Kawamura

2004 Aspen Winter Conference on Gravitational Waves

Gravitational Wave Advanced Detector Workshops

Feb. 15 - 21, 2004

40m Team:A. Weinstein, O. Miyakawa, M. Smith, J. Heefner, B. Abbott,

S. Vass, R. Taylor, L. Goggin, F. Kawazoe, S. Sakata, and R. Ward

Aspen 2004 2LIGO-G040039-02-R

Objectives

Develop lock acquisition procedure of detuned Resonant Sideband Extraction (RSE),

Characterize noise mechanism, Verify optical spring effect, Develop DC readout scheme, etc.

for Advanced LIGO, LCGT,

and other future GW detectors

Aspen 2004 3LIGO-G040039-02-R

Target Sensitivity ofAdvanced LIGO and 40m

Aspen 2004 4LIGO-G040039-02-R

Important Achievement (1)Installation of FP Michelson

September, 2003September, 2003

Four TMs and BS: installed

PSL

ETMy

ETMx

ITMy

ITMxBS

MC

Aspen 2004 5LIGO-G040039-02-R

Important Achievement (2)Modification of PSL

October 2003October 2003 Stabilize frequency of light with Reference Cavity (RF) after

Pre-Mode Cleaner (PMC) instead of before PMC Noise sources associated with PMC and steering optics after

PMC should be suppressed![S.Kawamura, “Configuration Study of Pre-Mode Cleaner and Reference Cavity in the 40m PSL System, LIGO-T030149-00-R (2003)][C. Mow-Lowry, R. Abbott, and B. Abbott, “Frequency Stability Servo Modifications Made at the 40 meter Laboratory”, LIGO-T030205-00D (2003)]

Laser

PD

PD

RC

PMC

Previous Configuration

Laser

PD

PD

RC

PMC

New Configuration

Aspen 2004 6LIGO-G040039-02-R

Important Achievement (3)Improvement of PSL Noise

October 2003October 2003

PSL noise improved above 1 kHz

New Calibration Method (AOM as a reference) used [S.Kawamura and O. Miyakawa, “Convenient and Reliable Method for Measuring Frequency Noise of the Pre-Stabilized Laser”, LIGO-T030239-00-R (2003)]

10-3

10-2

10-1

100

101

102

103

104

105

Fre

qu

en

cy n

oise

[Hz/

Hz1/

2 ]

101

102

103

104

105

Frequency[Hz]

07/08/2003 PSL old layout10/07/2003 PSL new-layoutPSL Requirement

PSL frequency noise measured by MC

Aspen 2004 7LIGO-G040039-02-R

Important Achievement (4)Lock Acquisition of FP Michelson

November 2003November 2003

FP Michelson locked Method similar to the one

used for TAMA Interesting phenomena

observed[S. Kawamura and O. Miyakawa, “Polarity of Michelson Length Signal Obtained at the Symmetric Port In a Fabry-Perot Michelson Interferometer”, LIGO-T030295-00-R (2004)]

~ POX

POY ITMX

ITMY

ETMX

ETMY

BS

SP

RF

PCLaser I

IQ

AP

QI

Aspen 2004 8LIGO-G040039-02-R

Important Achievement (5)Spectrum of FP Michelson

December 2003December 2003

Displacement spectrum obtained

With all the whitening/de-whitening filters ON

Convenient calibration method (Michelson mid-fringe locking) used[S. Kawamura, O. Miyakawa, and S. Sakata, “Calibration of the 40m Fabry-Perot Michelson Interferometer”, LIGO-T030287-00-R (2003)]

10-17

10-16

10-15

10-14

10-13

10-12

10-11

10-10

10-9

Dis

pla

cem

en

t n

ois

e[m

/Hz1/

2 ]

101

2 3 4 5 6 7

102

2 3 4 5 6 7

103

2 3 4 5 6 7

104

Frequency[Hz]

Displacement noise of 40m FPMI12/30/2003

Aspen 2004 9LIGO-G040039-02-R

Important Achievement (6)Installation of PRM and SEM

February 2004February 2004 Power Recycling Mirror (PRM) and Signal Extraction

Mirror (SEM) installed

PSL

ETMy

ETMx

ITMy

ITMxBSPRM

SEM

MC

Aspen 2004 10LIGO-G040039-02-R

Signal Extraction Method

ETMy

ETMx

ITMy

ITMxBSPRM

SEM

Carrier

+f1 f1 +f2 f2

Carrier

+f1 f1 +f2 f2

PRC

Carrier

+f1 f1 +f2 f2

SEC

Anti-Resonant

Detuned

Phase: flipped

Off-Resonant

f1 :33MHzf2 :166MHz

Aspen 2004 11LIGO-G040039-02-R

Signal Extraction Matrix

Laser

ETMy

ETMx

ITMy

ITMxBS

PRM

SEM

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.

Dem. Phase

L L l l l s

SP f1 10 1 -3.8E-9

-1.2E-3

-1.3E-6

-2.3E-6

AP f2 271 -4.8E-9

1 1.2E-8

1.3E-3

-1.7E-8

SP f1 f2 189,32

-1.7E-3

-3.0E-4

1 -3.2E-2

-1.0E-1

AP f1 f2 4,81 -6.2E-4

1.5E-3

7.5E-1

1 7.1E-2

PO f1 f2 164,12

3.6E-3

2.7E-3

4.6E-1

-2.3E-2

1

Calculated by FINESSE (A. Freise: http://www.rzg.mpg.de/~adf/)

PO: light from BS to ITMy

Aspen 2004 12LIGO-G040039-02-R

Double Demodulation

0 50 100 150 200 250 300 3500

50

100

150

200

250

300

350

Demodulation Phase of f1

Dem

odul

atio

n Pha

se o

f f2

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

- 0.1

- 0.1

- 0.1

- 0.1

- 0.1

-0.1

- 0.1

-0.1

0

0

0

0

0

0

0

0

0

0

0

0.1

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

0.2

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

-0.03

- 0.03

- 0.02

- 0.02

- 0.0

2

- 0.02

- 0.02

- 0.02

- 0.02

-0.02

-0.0

1

- 0.01

-0.01

- 0.01

-0.01

-0.01

- 0.01

-0.0

1

- 0.01

0

0

0

0

0

0

0

0

0

0

0.01

0.01

0.01

0.01

0.01

0.01

0.01

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

0.030.03

0.04

0.04

0.04

0.04

- 0.1

- 0.1

- 0.1

- 0.1

-0.05

- 0.05

- 0.05

- 0.05

- 0.05

- 0.05

- 0.05

0

0 0

0

0

0

0

0

0

0

0

0

0

0.05

0.05

0.05

0.05

0.050.05

0.05

0.1

0.1

0.1

0.1

dc=0l+l-ls

Double Demodulation used for l+, l-, and ls

Demodulation phases optimized to suppress DC and to maximize desired signal[S.Kawamura, “Signal Extraction Matrix of the 40m Detuned RSE Prototype”, LIGO-T040010-00-R (2004)]

Aspen 2004 13LIGO-G040039-02-R

Length Tolerances

Acceptable cavity length deviations from the ideal points: 6 cm for l Example: Signal matrix with l deviation of 1 cm

3 mm for l 3 mm for ls

S. Kawamura, “Signal Extraction Matrix of the 40m Detuned RSE Prototype”, LIGO-T040010-00-R (2004)

Port Dem. Freq.

Dem. Phase

L L l l l s

SP f1 3341

-7.6E-9

-1.2E-3

-4.1E-6

-2.3E-6

AP f2 230 -1.3E-9

13.0E-

81.3E-

3-1.7E-

8

SP f1 f2

162,73

-6.5E-4

3.5E-4

1-5.6E-

21.3E-

1

AP f1 f2

173,218

1.5E-3

4.2E-4

-2.1 1-2.4E-

1

PO f1 f2

329,153

1.1E-3

2.7E-3

2.6-1.6E-

11

Aspen 2004 14LIGO-G040039-02-R

Lock Acquisition of Detuned RSE

Central part: not disturbed by lock status change of arm cavity Question: Not disturbed by flash of SBs or SBs of SBs in arms? Promising: TAMA using 3rd harmonic demodulation in PRFPMI

ETMy

ETMx

ITMy

ITMxBSPRM

SEM

2. lock arm cavities1. lock central part using beat signal between f1 and f2

Aspen 2004 15LIGO-G040039-02-R

Lock Acquisition of Central Part

Ideal Procedure: Lock one by one

[for example]

Step 1: Lock l+ robustly

Step 2: Lock l- robustly

Step 3: Lock ls

Find primary signal not disturbed by the other two DOFs Find secondary signal not disturbed by the residual DOF

ITMy

ITMxBSPRM

SEM

Step 1Step 2Step 3

Aspen 2004 16LIGO-G040039-02-R

Quality of l+ Signal (dc=0, l+:Max)

-150 -100 -50 0 50 100 150-0.01

-0.008

-0.006

-0.004

-0.002

0

0.002

0.004

0.006

0.008

0.01

l+

Erro

r Sig

nal

No- arm detuned RSE, DDM at SP, phase1=189, phase2=33 (dc=0)32 (dc=0)

Aspen 2004 17LIGO-G040039-02-R

Dependence ofl+ Signal (dc=0, l+:Max) on l-

Aspen 2004 18LIGO-G040039-02-R

Dependence of l+ Signal on Demodulation Phases

-150 -100 -50 0 50 100 150-0.01

-0.008

-0.006

-0.004

-0.002

0

0.002

0.004

0.006

0.008

0.01

l+

Erro

r Sig

nal

No- arm detuned RSE, DDM at SP, phase1=189 (dc=0), phase2: swept

phase2=0phase2=32 (dc=0)phase2=60phase2=88 (symmetric)phase2=120phase2=150phase2=180

-150 -100 -50 0 50 100 150-5

-4

-3

-2

-1

0

1

2

3

4

5x 10- 3

l+

Erro

r Sig

nal

No- arm detuned RSE, DDM at SP, phase1:Swept, phase2=32 (symmetric)

phase1=180 (max)phase1=210phase1=240phase1=270phase1=300phase1=330phase1=360

Aspen 2004 19LIGO-G040039-02-R

Quality of l+ Signal (Symmetric, dc0)

-150 -100 -50 0 50 100 150-5

-4

-3

-2

-1

0

1

2

3

4

5x 10- 3

l+

Erro

r Sig

nal

No- arm detuned RSE, DDM at SP, phase1=180, phase2=32 (symmetric)88 (symmetric)

Aspen 2004 20LIGO-G040039-02-R

Dependence ofl+ Signal (Symmetric, dc0) on l-

Aspen 2004 21LIGO-G040039-02-R

Dependence ofl+ Signal (Symmetric, dc0) on ls

Aspen 2004 22LIGO-G040039-02-R

Dependence of l+ Signal (Symmetric, dc0) on l- and ls

Aspen 2004 23LIGO-G040039-02-R

Beat between f1 andNon-Resonant SB f3 (AM)

Carrier

+f1 f1 +f2 f2 +f3 f3

Beat

Hint: G. Heinzel at Garching 30m

Aspen 2004 24LIGO-G040039-02-R

Dependence of Beat Signalbetween f1 and f3 on l-

Aspen 2004 25LIGO-G040039-02-R

Dependence of Beat Signalbetween f1 and f3 on ls

Aspen 2004 26LIGO-G040039-02-R

Quality of l- Signal

-150 -100 -50 0 50 100 150-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1x 10- 3

l-

Erro

r Sig

nal

No- arm detuned RSE, DDM at AP, phase1=4 , phase2=81 (dc=0)

Aspen 2004 27LIGO-G040039-02-R

Dependence of l- Signal on ls

Aspen 2004 28LIGO-G040039-02-R

l- Signal Divided byAP signal with different Dem. Phase

-150 -100 -50 0 50 100 150

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

x 10- 3

l-

Erro

r Sig

nal

No- arm detuned RSE, DDM at AP, phase1=96, phase2=81 (Symmetric)

-150 -100 -50 0 50 100 150-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1x 10- 3

l-

Erro

r Sig

nal

No- arm detuned RSE, DDM at AP, phase1=4 , phase2=81 (dc=0)

Divided by

Hint: H. Grote at GEO

Aspen 2004 29LIGO-G040039-02-R

Dependence of Dividedl- Signal on ls

Aspen 2004 30LIGO-G040039-02-R

Dependence of Dividedl- Signal on l+

Aspen 2004 31LIGO-G040039-02-R

Quality of ls Signal

-150 -100 -50 0 50 100 150-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0.1

ls

Erro

r Sig

nal

No- arm detuned RSE, DDM at PO, phase1=164, phase2=12 (dc=0)

Aspen 2004 32LIGO-G040039-02-R

Dependence of ls Signal on l+

Aspen 2004 33LIGO-G040039-02-R

Looking for Good Signal …

Have tried the following, but not significant improvement… f1-dem, f2-dem For l+:

Single sideband f2, AM f2

NR pm, am, single sideband f3:

(f2-f3)-dem, (f1+f3)-dem For l-, ls:

Signal divided by the following:

2f1-dem, 2f2-dem, DDM with different dem phases, (f2-2f1)-dem

Aspen 2004 34LIGO-G040039-02-R

We Should Try More …

Analyze error signal with one DOF locked Try more various signals including mechanical dither

signal Develop quick acquisition method Tighten suspended optics rigidly with respect to local

frame, then manually bring three DOFs near lock point to acquire lock?

Aspen 2004 35LIGO-G040039-02-R

Summary

Lots of achievements; experiment on 40m going very fast and smoothly

Almost ready to try lock acquisition Lock acquisition: not so easy Need more investigation for lock acquisition

Hope we succeed in locking detuned RSE very soon!