CNRS LKB – Task T1CNRS LKB – Task T1

Current status of the experiment on optomechanical coupling

Sensitivity: 5.10 20 m.Hz

1/2

New high-finesse, high-power cavity (F 200

000)

Objectives: observation of quantum noises and quantum limits

Expected sensitivity 10 21 m.Hz

1/2

CNRS LKB – Task T1CNRS LKB – Task T1

Experiment on thermal noise at low frequency

Current status: development of the laser sourceIntensity stabilization at the shot noise level at low

frequency

Objectives:sensitivity 10

20 m.Hz

½ at frequency > 100 Hz

Theoretical study of thermoelastic noises Frequency dependence due to non-adiabatic conditions

Task T2 – Measurement of photo-Task T2 – Measurement of photo-elastic noiseelastic noise

Photo-thermal noise is due to the conduction inside mirrors and coatings of the heat induced by photon absorption.

It can be tested using the photo-elastic effect induced by an intensity modulation of the light entering a Fabry-Perot cavity

Objectives : - observation of photo-elastic effects- dependence with temperature down to tenths of K- test of low optical loss coatings

Task T2 – Measurement of photo-Task T2 – Measurement of photo-elastic noiseelastic noise

Measurement of photo-thermal effect induced by an intensity-modulated light beam

Experiment: M. De Rosa, L. Conti, M. Cerdonio, M. Pinard, F. Marin,Phys. Rev. Lett. 89, 237402 (2002)

Theory: M. Cerdonio, L. Conti, A. Heidmann, M. Pinard,Phys. Rev. D 63, 082003 (2001)

CNRS LKB – Task T2CNRS LKB – Task T2

Test and set-up of high-finesse cryogenic cavities

Cavities with low-loss coatings suitable for cryogenic applications

Theoretical study of photo-elastic noise

Theoretical investigation on light absorption effects of coatings at low temperature

Measurement of photo-thermal effect at low temperature

Using the experiment on opto-mechanical coupling with a cryogenic cavity and an intensity-modulated laser beam

CNRS LKB – Task T3CNRS LKB – Task T3

Developments of Fabry-Perot cavities with wide area read-out- Folded FP cavity

(collaboration with LENS)

Theoretical calculation of selective read-out for dual-sphere detectors with several optical sensors

- Concave-convex cavities

Tests of thermal noise reduction and signal-to-noise enhancement with wide area cavitiesDirect measurement of thermal noise background

Dependence with the effective area