11-15 September 2007@Sendai Civic Auditorium11-15 September 2007@Sendai Civic AuditoriumTAUP2007 (Sendai) TAUP2007 (Sendai)
Displacement noise free interferometoryfor gravitational wave detection
National Astronomical Observatory of Japan,Ochanomizu UniversityA,
LIGO project, California Institute of TechnologyB
Kyoto UniversityC,Max-Planck-Institut für GravitationsphysikD
Shuichi Sato, Keiko KokeyamaA, Seiji Kawamura, Robert L.WardB,Atsushi NishizawaC, Yanbei ChenD, Archana PaiD and Kentaro SomiyaD
Introduction
Displacement noise
Fundamental noises: Seismic, thermal, radiation pressure, etc…
Practical/technical noises: alignment noise, electronics noise, etc…
If, the displacement noise has gone…
Shot-noise-limited interferometer in all frequency band
If, it is shot-noise-limited interferometer…
The sensitivity goes better with laser power
However…
Currently suggested DFI does not apply, for audio frequency band
Sensitivity
Frequency
Cancellation ofDisplacement noise
Better shot noise level
11-15 September 2007@Sendai Civic Auditorium11-15 September 2007@Sendai Civic AuditoriumTAUP2007 (Sendai) TAUP2007 (Sendai)
History
ReferenceKawamura and Chen, PRL 93 (2004) 211103Chen and Kawamura, PRL 96 (2006) 231102Chen, Pai, Somiya, Kawamura, Sato, Kokeyama and Ward,
PRL 97 (2006) 151103, (gr-qc/0603054)Sato, Kawamura, Kokeyama, Ward, Chen, Pai and Somiya,
PRL 98 (2007) 141101, (gr-qc/0608095)
11-15 September 2007@Sendai Civic Auditorium11-15 September 2007@Sendai Civic AuditoriumTAUP2007 (Sendai) TAUP2007 (Sendai)
History
ReferenceKawamura and Chen, PRL 93 (2004) 211103Chen and Kawamura, PRL 96 (2006) 231102Chen, Pai, Somiya, Kawamura, Sato, Kokeyama and Ward,
PRL 97 (2006) 151103, (gr-qc/0603054)Sato, Kawamura, Kokeyama, Ward, Chen, Pai and Somiya,
PRL 98 (2007) 141101, (gr-qc/0608095)
11-15 September 2007@Sendai Civic Auditorium11-15 September 2007@Sendai Civic AuditoriumTAUP2007 (Sendai) TAUP2007 (Sendai)
Principle of DFIGWs
DisplacementDisplacement
Point1: Difference of effects, GWs v.s. Displacement
GWs: accumulated phase shift on the whole path
Displacement: instantaneous
Point2: Multiple interferometer network
Share the displacement information
Manipulation of the signals
Cancel the displacement information
Remaining GWs signals
DFI: different approach
Suppression v.s. Cancellation
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QuickTime˛ Ç∆GIF êLí£ÉvÉçÉOÉâÉÄ
ǙDZÇÃÉsÉNÉ`ÉÉÇ å©ÇÈÇΩÇflÇ…ÇÕïKóvÇ≈Ç∑ÅB
DFI configuration
3-dimensional Mach-Zehnder interferometer
Light travels on the rigdeline
2-sets of bi-directional Mach-Zehnder interferometers
2-Beam Splitters at the tops
4-Folding mirrors at the side apexes
One of DFI configuration (most simple)
Still looking for other configuration
11-15 September 2007@Sendai Civic Auditorium11-15 September 2007@Sendai Civic AuditoriumTAUP2007 (Sendai) TAUP2007 (Sendai)
DFI features
3-dimensional Mach-Zehnder interferometer
Combination of 4-interferometer’s output
Complete cancellation of optic’s displacements
Remaining GW signals
Effective frequency fc ~100MHz for L=1mChen et.al, PRL 97 (2006) 151103
11-15 September 2007@Sendai Civic Auditorium11-15 September 2007@Sendai Civic AuditoriumTAUP2007 (Sendai) TAUP2007 (Sendai)
DFI features
3-dimensional Mach-Zehnder interferometer
Combination of 4-interferometer’s output
Complete cancellation of optic’s displacements
Remaining GW signals
Effective frequency fc ~100MHz for L=1mChen et.al, PRL 97 (2006) 151103
11-15 September 2007@Sendai Civic Auditorium11-15 September 2007@Sendai Civic AuditoriumTAUP2007 (Sendai) TAUP2007 (Sendai)
Experiment (1) -Optical layout-
Proof-of-principle experiment
To confirm
Cancellation of FM displacement
Cancellation of BS displacement
Finite sensitivity to GWs signals
Partial demonstration
Using one set of bi-directional Mach-Zehnder interferometer
11-15 September 2007@Sendai Civic Auditorium11-15 September 2007@Sendai Civic AuditoriumTAUP2007 (Sendai) TAUP2007 (Sendai)
Experiment (2) -Setup-
(前回の学会で報告)For GWs
For displacementnoise of FM
2-D bi-directional MZI
Sharing optical paths
Transfer function measurement
From D/GWs simulator to DFI
D/GWs simulation
FM: EOM at the center of the path
GWs: EOM at the asymmetric position -> makes “GWs-like” signal
11-15 September 2007@Sendai Civic Auditorium11-15 September 2007@Sendai Civic AuditoriumTAUP2007 (Sendai) TAUP2007 (Sendai)
Experiment (3) -Cancellation of FM displacement-
180
90
0
-90
-180
Phase [degree]
105
106
107
108
Frequency [Hz]
-110
-100
-90
-80
-70
-60
-50
Amplitude [dB]
MAX50dBMZI2 output
MZI1 output
DFI outputtuned@25MHz
DFI output
11-15 September 2007@Sendai Civic Auditorium11-15 September 2007@Sendai Civic AuditoriumTAUP2007 (Sendai) TAUP2007 (Sendai)
Experiment (4) -Sensitivity to GWs-
-110
-100
-90
-80
-70
-60
Amplitude [dB]
105
106
107
108
Frequency [Hz]
180
90
0
-90
-180
Phase [degree]
GWs: remaining around fc
MZI2 output
MZI1 output
DFI output
11-15 September 2007@Sendai Civic Auditorium11-15 September 2007@Sendai Civic AuditoriumTAUP2007 (Sendai) TAUP2007 (Sendai)
First DFI using conventional interferometory
DFI feature was confirmed
FM cancellation
(BS cancellation: in separate experiment)
Sensitive to GWs
Next:
Spectrum (sensitivity) measurement of DFI: ongoing
3-D complete DFI: just started
Invention of new configuration for practical application
Summary and next
11-15 September 2007@Sendai Civic Auditorium11-15 September 2007@Sendai Civic AuditoriumTAUP2007 (Sendai) TAUP2007 (Sendai)
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