LISA R&D activities at APC A status report Hubert Halloin

LISA France – 02 February R&D activities at APC Recent implication of APC in the LISA R&D (~ 1.5 year) : Recent implication of APC in the LISA R&D (~ 1.5 year) : –LISA Pathfinder (Laser Modulator) : Validation of test procedures (  Contraves) Validation of test procedures (  Contraves) Acquire experience for further experiments … Acquire experience for further experiments … –LISA : Laser stabilization Laser stabilization Realization of a ‘LISA-representative’ laboratory Realization of a ‘LISA-representative’ laboratory

LISA France – 02 February The LISA APC M. Abbès (electronics engineer) M. Abbès (electronics engineer) G. Auger (director of research) G. Auger (director of research) P. Binetruy (professor, director of the APC) P. Binetruy (professor, director of the APC) H. Halloin (assistant professor) H. Halloin (assistant professor) O. Jeannin (optical engineer) O. Jeannin (optical engineer) A. Petiteau (PhD student) A. Petiteau (PhD student) E. Plagnol (director of research) E. Plagnol (director of research) P. Prat (electronics engineer, NPM for LISA Pathfinder) P. Prat (electronics engineer, NPM for LISA Pathfinder) E. de Vismes (electronics engineer) E. de Vismes (electronics engineer)

LISA France – 02 February LISA Optical Test Equipment Centered on the interferometric signal reconstruction (excluding inertial masses) Centered on the interferometric signal reconstruction (excluding inertial masses) “LISA-representative” test bench “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) Supported by the French Space Agency (CNES) In collaboration with : In collaboration with : –A. Brillet (O.C.A) : Laser stabilization for Virgo –SYRTE : R&D in time/frequency standards and references

LISA France – 02 February Development roadmap 3 major steps : 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

LISA France – 02 February Laser stabilization Selected technique : saturated absorption on molecular iodine 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 d’Azur (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 : Ways of improvements : –Better thermal, mechanical and electronics stability –Improved feedback loop –Low pressure enclosure –Possible use of low pressure, non-saturated I 2 cells at ~0°C, in collaboration with the BIPM (better thermal stability) Main technical and performance concerns : Main technical and performance concerns : –Overall frequency stability –Thermal and vibration control –Wave front quality of the IR beam after frequency doubling –I 2 reactivity (in case of non saturated cells)

LISA France – 02 February Laser stabilization : foreseen design Current status : Current status : –Electronic cards development / realizations –Precise mechanical and optical design –Mounting to begin in Feb 2007 Iodine cell λ=532nm AOM Laser 1Feedback electronics λ=1064nm Laser MHz 20 MHz beat signal + laser noise Iodine cell λ=532nm AOM Laser 2 Feedback electronics λ=1064nm Laser 2 80 MHz

LISA France – 02 February LISA in the lab « Representative » reconstruction of the interferometric signal : « 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 : Facility for methods and equipments tests : –Phasemeters –USO –TDI ranging –Arm locking –… LISA … … in the lab

LISA France – 02 February Simulating the propagation delays Global idea : Global idea : –only the relative LF (<1Hz) 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 Measurements Doppler ~10 -6 Hz LF laser phase noise <1 Hz HF laser phase noise >1 Hz (not of interest …)

LISA France – 02 February LISA in the lab 1 st step : phase locking the lasers 1 st step : phase locking the lasers –Master laser reference noise –Null relative phase noise (modulo frequency offsets) –“Of the shelf” efficient techniques

LISA France – 02 February Master laser Phase locking Laser 2 locking Laser 3 locking  LISA in the lab : first idea … Laser 1 May be laser 1, 2 or 3 Iodine stabilized

LISA France – 02 February LISA in the lab 1 st step : phase locking the lasers 1 st step : phase locking the lasers –Master laser reference noise –Null relative phase noise (modulo frequency offsets) –“Of the shelf” efficient techniques 2 nd step : noise delays simulation 2 nd 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

LISA France – 02 February Principle design, to be precised … Principle design, to be precised … Continuity of precedent work (stabilization,  - meter) + R&D (locking, delays) Continuity of precedent work (stabilization,  - meter) + R&D (locking, delays) Planned for 2008 … Planned for 2008 … Master laser AOM Phase locking Laser 2 locking Laser 3 locking AOM LF noise generator (statistically. representative) FM  Doppler shift PM  LF phase noise Digital delays  12  16s  13  16s L2 local  L3 local  L2 delayed  L3 delayed  Simulated delays of noise L1 “local” L1 “delayed”  LISA in the lab : first idea … Laser 1

LISA France – 02 February Conclusions Continuation of LISA Pathfinder activities Continuation of LISA Pathfinder activities R&D on iodine stabilization : R&D 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) Strong support of the French space agency (CNES) Collaboration with : Collaboration with : –OCA / Artemis (A. Brillet) –SYRTE