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LISA R&D activities at APC A status report Hubert Halloin R&D activities at APC Recent implication of APC in the LISA R&D (~ 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 LISA France – 02 February 2007 2 The LISA team @ 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) LISA France – 02 February 2007 3 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 : R&D in time/frequency standards and references LISA France – 02 February 2007 4 Development roadmap 3 major steps : – Laser stabilization and characterization Short term ~1 year – Definition and development of a dedicated phasemeter Long term ~5 years – LISA test bench (3 lasers, variable propagation delays, realistic phasemeters,…) LISA France – 02 February 2007 5 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 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 : – – – – Better thermal, mechanical and electronics stability Improved feedback loop Low pressure enclosure Possible use of low pressure, non-saturated I2 cells at ~0°C, 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 LISA France – 02 February 2007 I2 reactivity (in case of non saturated cells) 6 Laser stabilization : foreseen design 160 MHz λ=532nm Laser 1 AOM Laser 1 Feedback electronics λ=1064nm Iodine cell 20 MHz beat signal + laser noise Iodine cell Feedback electronics Laser 2 λ=1064nm λ=532nm AOM Laser 2 80 MHz Current status : – Electronic cards development / realizations – Precise mechanical and optical design – Mounting to begin in Feb 2007 LISA France – 02 February 2007 7 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 … LISA … LISA France – 02 February 2007 … in the lab 8 Simulating the propagation delays < 1H z ¢ Álaser (t) = ¢ ! (t) ¢t + ¢ Áfnoi se (t) Measurements Doppler ~10-6 Hz LF laser phase noise <1 Hz > 1H z [+ ¢ Áfnoi se (t)] HF laser phase noise >1 Hz (not of interest …) 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 LISA France – 02 February 2007 9 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 LISA France – 02 February 2007 10 LISA in the lab : first idea … Master laser Laser 1 Phase locking May be laser 1, 2 or 3 Iodine stabilized Phase locking Laser 2 locking Laser 3 locking LISA France – 02 February 2007 11 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) : ¢ ! (t) = ! 0 + ! D oppler (t) + z d©fn <oi 1H se (t) dt – Low frequency noise can be easily digitally delayed – Possibility to simulate 1 year of data (Doppler, LISA France – 02 February 2007 laser noise, GW ?) within hours 12 LISA in the lab : first idea … Master laser Laser 1 Phase locking Phase locking AOM Laser 2 locking L1 “delayed” Digital delays L1 “local” AOM Simulated delays of noise 1316s AOM L3 delayed L2 delayed 1216s Laser 3 locking LF noise generator (statistically. representative) FM Doppler shift PM LF phase noise L3 local L2 local Principle design, to be precised … Continuity of precedent work (stabilization, meter) + R&D (locking, delays) Planned for 2008 … LISA France – 02 February 2007 13 Conclusions Continuation of LISA Pathfinder activities 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) Collaboration with : – OCA / Artemis (A. Brillet) – SYRTE LISA France – 02 February 2007 14