LISA R&D activities at LISA R&D activities at APC APC

A status reportA status report

Hubert HalloinHubert Halloin

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R&D activities at APCR&D activities at APC

Recent implication of APC in the LISA Recent implication of APC in the LISA R&D (~ 1.5 year) :R&D (~ 1.5 year) :– LISA Pathfinder (Laser Modulator) :LISA Pathfinder (Laser Modulator) :

Validation of test procedures (Validation of test procedures ( Contraves) Contraves) Acquire experience for further experiments …Acquire experience for further experiments …

– LISA :LISA : Laser stabilizationLaser stabilization Realization of a ‘LISA-representative’ laboratoryRealization of a ‘LISA-representative’ laboratory

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The LISA team @ APCThe LISA team @ APC

M. Abbès (electronics M. Abbès (electronics engineer)engineer)

G. Auger (director of G. Auger (director of research)research)

P. Binetruy (professor, P. Binetruy (professor, director of the APC)director of the APC)

H. Halloin (assistant H. Halloin (assistant professor)professor)

O. Jeannin (optical O. Jeannin (optical engineer)engineer)

A. Petiteau (PhD student)A. Petiteau (PhD student)

E. Plagnol (director of E. Plagnol (director of research)research)

P. Prat (electronics P. Prat (electronics engineer, NPM for LISA engineer, NPM for LISA Pathfinder)Pathfinder)

E. de Vismes (electronics E. de Vismes (electronics

engineer)engineer)

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LISA Optical Test LISA Optical Test EquipmentEquipment

Centered on the interferometric signal reconstruction (excluding Centered on the interferometric signal reconstruction (excluding inertial masses)inertial masses)

““LISA-representative” test benchLISA-representative” test bench– What optical devices / electronics for the “best” signal extraction ?What optical devices / electronics for the “best” signal extraction ?– Characterization of present techniques (laser, phasemeters, …) Characterization of present techniques (laser, phasemeters, …) – Test facility for LISA instrumental developments.Test facility for LISA instrumental developments.– Conformation to / interaction with LISA simulationConformation to / interaction with LISA simulation– ““Realistic” performance of signal reconstruction algorithms (TDI,…) 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 VirgoA. Brillet (O.C.A) : Laser stabilization for Virgo– SYRTE : R&D in time/frequency standards and referencesSYRTE : R&D in time/frequency standards and references

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Development roadmapDevelopment roadmap

3 major steps :3 major steps :– Laser stabilization and characterizationLaser stabilization and characterization

– Definition and development of a dedicated Definition and development of a dedicated phasemeterphasemeter

– LISA test bench (3 lasers, variable propagation LISA test bench (3 lasers, variable propagation delays, realistic phasemeters,…)delays, realistic phasemeters,…)

Short term~1 year

Long term~5 years

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Laser stabilizationLaser stabilization

Selected technique : saturated absorption on molecular iodineSelected technique : saturated absorption on molecular iodine– Absolute reference (no long term drift, easier arm-locking ?).Absolute reference (no long term drift, easier arm-locking ?).– Already tested and promising for LISA : successful experiments at Already tested and promising for LISA : successful experiments at

Observatoire de la Côte d’Azur (Nice, France) and GSFC. Observatoire de la Côte d’Azur (Nice, France) and GSFC. – Financial support from the French space agency (CNES) Financial support from the French space agency (CNES) – Collaboration with the OCA/ARTEMIS (A. Brillet) and the SYRTECollaboration with the OCA/ARTEMIS (A. Brillet) and the SYRTE

Ways of improvements :Ways of improvements :– Better thermal, mechanical and electronics stabilityBetter thermal, mechanical and electronics stability– Improved feedback loopImproved feedback loop– Low pressure enclosureLow pressure enclosure– Possible use of low pressure, non-saturated IPossible use of low pressure, non-saturated I22 cells at ~0°C, in cells at ~0°C, in

collaboration with the BIPM (better thermal stability)collaboration with the BIPM (better thermal stability)

Main technical and performance concerns :Main technical and performance concerns :– Overall frequency stabilityOverall frequency stability– Thermal and vibration controlThermal and vibration control– Wave front quality of the IR beam after frequency doubling Wave front quality of the IR beam after frequency doubling – II22 reactivity (in case of non saturated cells) reactivity (in case of non saturated cells)

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Laser stabilization : foreseen Laser stabilization : foreseen designdesign

Current status :Current status :– Electronic cards development / realizationsElectronic cards development / realizations– Precise mechanical and optical designPrecise mechanical and optical design– Mounting to begin in Feb 2007Mounting to begin in Feb 2007

Iodine cell

λ=532nmAOM

Laser 1 Feedback electronicsλ=1064nm

Laser 1160 MHz

20 MHz beat signal+ laser noise

Iodine cell

λ=532nm AOM

Laser 2Feedback electronicsλ=1064nm

Laser 2

80 MHz

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LISA in the labLISA in the lab

« Representative » reconstruction of the interferometric « Representative » reconstruction of the interferometric signal :signal :– Noise propagation delay (16 s !)Noise propagation delay (16 s !)– Spectral perturbations (Doppler, Sagnac, etc.)Spectral perturbations (Doppler, Sagnac, etc.)– GW simulation ?GW simulation ?– Reconstruction algorithm(s) (TDI) : effective performance, Reconstruction algorithm(s) (TDI) : effective performance,

comparison with numerical simulations.comparison with numerical simulations.

Facility for methods and equipments tests :Facility for methods and equipments tests :– PhasemetersPhasemeters– USOUSO– TDI rangingTDI ranging– Arm lockingArm locking– ……

LISA … … in the lab

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Simulating the propagation Simulating the propagation delaysdelays

Global idea : Global idea : – only the relative LF (<1Hz) phase noise + frequency only the relative LF (<1Hz) phase noise + frequency

shift has to be « propagated »shift has to be « propagated »– No need to delay the « full » phase data (i.e. carrier No need to delay the « full » phase data (i.e. carrier

+ phase noise)+ phase noise)– Small information content (low frequency) Small information content (low frequency) can be can be

easily digitally delayedeasily digitally delayed

¢ Álaser(t) = ¢ ! (t) ¢t +¢ Áf <1H znoise (t) [+¢ Áf >1Hz

noise (t)]¢ Álaser(t) = ¢ ! (t) ¢t +¢ Áf <1H znoise (t) [+¢ Áf >1Hz

noise (t)]

Measurements Doppler~10-6 Hz

LF laser phase noise<1 Hz

HF laser phase noise>1 Hz (not of interest …)

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LISA in the labLISA in the lab

11stst step : phase locking the lasers step : phase locking the lasers– Master laser reference noiseMaster laser reference noise– Null relative phase noise (modulo Null relative phase noise (modulo

frequency offsets)frequency offsets)– ““Of the shelf” efficient techniquesOf the shelf” efficient techniques

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Master laser

Phase locking

Phase locking

Laser 2 locking

Laser 3locking

LISA in the lab : first idea LISA in the lab : first idea ……

Laser 1

May be laser 1, 2 or 3Iodine stabilized

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LISA in the labLISA in the lab

11stst step : phase locking the lasers step : phase locking the lasers– Master laser reference noiseMaster laser reference noise– Null relative phase noise (modulo Null relative phase noise (modulo

frequency offsets)frequency offsets)– ““Of the shelf” efficient techniquesOf the shelf” efficient techniques

22ndnd step : noise delays simulation step : noise delays simulation– Use of AOM (frequency shifts) : Use of AOM (frequency shifts) :

– Low frequency noise can be easily digitally Low frequency noise can be easily digitally delayeddelayed

– Possibility to simulate 1 year of data Possibility to simulate 1 year of data (Doppler, laser noise, GW ?) within hours(Doppler, laser noise, GW ?) within hours

¢ ! (t) = ! 0 +! Doppler(t) + d©f <1H znoisedt (t)¢ ! (t) = ! 0 +! Doppler(t) + d©f <1H z

noisedt (t)

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Principle design, to be precised …Principle design, to be precised … Continuity of precedent work Continuity of precedent work

(stabilization, (stabilization, -meter) + R&D (locking, -meter) + R&D (locking, delays)delays)

Planned for 2008 …Planned for 2008 …

Master laser

AOMPhase locking

Phase locking

Laser 2 locking

Laser 3locking

AOM

AOM LF noise generator (statistically.

representative)FM Doppler shiftPM LF phase noise

Digital delays

1216s

1316s

L2 local

L3 local

L2 delayed

L3 delayed

Simulated delays of noise

L1 “local”

L1 “delayed”

LISA in the lab : first idea LISA in the lab : first idea ……

Laser 1

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ConclusionsConclusions

Continuation of LISA Pathfinder activitiesContinuation of LISA Pathfinder activities

R&D on iodine stabilization :R&D on iodine stabilization :– Optical and electronics design startedOptical and electronics design started– Mounting to begin within a few weeks (on our new site Mounting to begin within a few weeks (on our new site

…)…)

Strong support of the French space agency Strong support of the French space agency (CNES)(CNES)

Collaboration with :Collaboration with :– OCA / Artemis (A. Brillet)OCA / Artemis (A. Brillet)– SYRTESYRTE