LISA R

1
LISA RD activities at APC

• A status report
• Hubert Halloin

2
RD activities at APC

• Recent implication of APC in the LISA RD ( 1.5
  year)
• LISA Pathfinder (Laser Modulator)
• Validation of test procedures (? Contraves)
• Acquire experience for further experiments
• LISA
• Laser stabilization
• Realization of a LISA-representative laboratory

3
The LISA team _at_ APC

• M. Abbès (electronics engineer)
• G. Auger (director of research)
• P. Binetruy (professor, director of the APC)
• H. Halloin (assistant professor)
• O. Jeannin (optical engineer)

• A. Petiteau (PhD student)
• E. Plagnol (director of research)
• P. Prat (electronics engineer, NPM for LISA
  Pathfinder)
• E. de Vismes (electronics engineer)

4
LISA Optical Test Equipment

• Centered on the interferometric signal
  reconstruction (excluding inertial masses)
• LISA-representative test bench
• What optical devices / electronics for the best
  signal extraction ?
• Characterization of present techniques (laser,
  phasemeters, )
• Test facility for LISA instrumental developments.
• Conformation to / interaction with LISA
  simulation
• Realistic performance of signal reconstruction
  algorithms (TDI,)
• Supported by the French Space Agency (CNES)
• In collaboration with
• A. Brillet (O.C.A) Laser stabilization for
  Virgo
• SYRTE RD in time/frequency standards and
  references

5
Development roadmap

• 3 major steps
• Laser stabilization and characterization
• Definition and development of a dedicated
  phasemeter
• LISA test bench (3 lasers, variable propagation
  delays, realistic phasemeters,)

Short term 1 year
Long term 5 years
6
Laser stabilization

• Selected technique saturated absorption on
  molecular iodine
• Absolute reference (no long term drift, easier
  arm-locking ?).
• Already tested and promising for LISA
  successful experiments at Observatoire de la Côte
  dAzur (Nice, France) and GSFC.
• Financial support from the French space agency
  (CNES)
• Collaboration with the OCA/ARTEMIS (A. Brillet)
  and the SYRTE
• Ways of improvements
• Better thermal, mechanical and electronics
  stability
• Improved feedback loop
• Low pressure enclosure
• Possible use of low pressure, non-saturated I2
  cells at 0C, in collaboration with the BIPM
  (better thermal stability)
• Main technical and performance concerns
• Overall frequency stability
• Thermal and vibration control
• Wave front quality of the IR beam after frequency
  doubling
• I2 reactivity (in case of non saturated cells)

7
Laser stabilization foreseen design

• Current status
• Electronic cards development / realizations
• Precise mechanical and optical design
• Mounting to begin in Feb 2007

8
LISA in the lab

•  Representative  reconstruction of the
  interferometric signal
• Noise propagation delay (16 s !)
• Spectral perturbations (Doppler, Sagnac, etc.)
• GW simulation ?
• Reconstruction algorithm(s) (TDI) effective
  performance, comparison with numerical
  simulations.
• Facility for methods and equipments tests
• Phasemeters
• USO
• TDI ranging
• Arm locking

in the lab
LISA
9
Simulating the propagation delays
Measurements
Doppler 10-6 Hz
LF laser phase noise lt1 Hz
HF laser phase noise gt1 Hz (not of interest )

• Global idea
• only the relative LF (lt1Hz) phase noise
  frequency shift has to be  propagated 
• No need to delay the  full  phase data (i.e.
  carrier phase noise)
• Small information content (low frequency) ? can
  be easily digitally delayed

10
LISA in the lab

• 1st step phase locking the lasers
• Master laser reference noise
• Null relative phase noise (modulo frequency
  offsets)
• Of the shelf efficient techniques

11
LISA in the lab first idea
May be laser 1, 2 or 3 Iodine stabilized
Master laser
Phase locking
Laser 1
Phase locking
Laser 2 locking
?
Laser 3locking
12
LISA in the lab

• 1st step phase locking the lasers
• Master laser reference noise
• Null relative phase noise (modulo frequency
  offsets)
• Of the shelf efficient techniques
• 2nd step noise delays simulation
• Use of AOM (frequency shifts)
• Low frequency noise can be easily digitally
  delayed
• Possibility to simulate 1 year of data (Doppler,
  laser noise, GW ?) within hours

13
LISA in the lab first idea
Master laser
Phase locking
Laser 1
AOM
Phase locking
Laser 2 locking
?
Laser 3locking
L1 delayed
Digital delays
L1 local
LF noise generator (statistically.
representative) FM ? Doppler shift PM ? LF phase
noise
AOM
?12?16s
Simulated delays of noise
AOM
?13?16s
?
?
?

• Principle design, to be precised
• Continuity of precedent work (stabilization,
  ?-meter) RD (locking, delays)
• Planned for 2008

?
L2 local
L3 local
L2 delayed
L3 delayed
14
Conclusions

• Continuation of LISA Pathfinder activities
• RD on iodine stabilization
• Optical and electronics design started
• Mounting to begin within a few weeks (on our new
  site )
• Strong support of the French space agency (CNES)
• Collaboration with
• OCA / Artemis (A. Brillet)
• SYRTE