Transcript LISA R&D activities at APC

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) :
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Validation of test procedures ( Contraves)
Acquire experience for further experiments …
– LISA :
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Laser stabilization
Realization of a ‘LISA-representative’ laboratory
LISA France – 02 February 2007
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The LISA team @ APC
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M. Abbès (electronics
engineer)
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G. Auger (director of
research)
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P. Binetruy (professor,
director of the APC)
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H. Halloin (assistant
professor)
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O. Jeannin (optical
engineer)
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A. Petiteau (PhD student)
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E. Plagnol (director of
research)
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P. Prat (electronics
engineer, NPM for LISA
Pathfinder)
E. de Vismes (electronics
engineer)
LISA France – 02 February 2007
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LISA Optical Test Equipment

Centered on the interferometric signal reconstruction (excluding inertial
masses)
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“LISA-representative” test bench
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–
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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)
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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
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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
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Laser stabilization
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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
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Ways of improvements :
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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 :
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–
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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)
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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
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Current status :
– Electronic cards development / realizations
– Precise mechanical and optical design
– Mounting to begin in Feb 2007
LISA France – 02 February 2007
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LISA in the lab
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« Representative » reconstruction of the interferometric signal :
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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 :
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Phasemeters
USO
TDI ranging
Arm locking
…
LISA …
LISA France – 02 February 2007
… in the lab
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Simulating the propagation delays
< 1H z
¢ Álaser (t) = ¢ ! (t) ¢t + ¢ Áfnoi
se (t)
Measurements
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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
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LISA in the lab
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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
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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
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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
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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
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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
1316s
AOM


L3
delayed

L2
delayed
1216s
Laser 3
locking
LF noise generator
(statistically.
representative)
FM  Doppler shift
PM  LF phase noise
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L3
local
L2
local
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Principle design, to be precised …
Continuity of precedent work (stabilization, meter) + R&D (locking, delays)
Planned for 2008 …
LISA France – 02 February 2007
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Conclusions
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Continuation of LISA Pathfinder activities
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R&D on iodine stabilization :
– Optical and electronics design started
– Mounting to begin within a few weeks (on our new site …)
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Strong support of the French space agency (CNES)
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Collaboration with :
– OCA / Artemis (A. Brillet)
– SYRTE
LISA France – 02 February 2007
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