Download Radiation pressure effects in interferometric measurements

Laboratoire Kastler Brossel, Paris
Radiation pressure effects
in interferometric measurements
A. Heidmann
P.-F. Cohadon
M. Pinard
T. Briant
O. Arcizet
C. Molinelli
T. Caniard
P. Verlot
J.-M. Courty
Quantum noises in interferometers
Two conjugate quantum noises:
• Laser noise (shot noise)
• Mirror motion due to radiation pressure
⇒ Quantum limits in interferometric measurements
Quantum noises in advanced configurations
Advanced Virgo sensitivity curve, M. Punturo (2004)
Quantum noise reduction
Many proposals to reduce quantum noises:
• Injection of squeezed states
• QND detection
• Dynamical effects with detuned interferometer
Buonanno et al, PRD (2001)
• Quantum locking of mirrors
Courty et al, PRL (2003)
Study of quantum noises in interferometers
Application of quantum optics techniques to GW interferometers
• Adaptation of squeezing
(low frequency, wideband effects)
• Constraints on the interferometer
(losses, …)
Objectives:
• Efficient and robust schemes
• Experimental tests of quantum noises
Kimble et al, PRD (2002)
Experimental tests of quantum noises
Injection of squeezing in an interferometer:
McKenzie et al, PRL (2002)
In dual-recycled interferometer: R. Schnabel et al, PRL (2005)
No demonstration of quantum effects of radiation pressure!
Experimental test of radiation pressure
Very sensitive optomechanical sensor
based on a high-finesse cavity
Current finesse:
Model system to study the coupling
between light and moving mirrors
Current sensitivity:
• Dynamical effects of radiation pressure
(parametric instability, optical damping)
• Quantum noises and noise reduction schemes
Quantum noises in optomechanical sensor
Compromise between phase and radiation pressure noises
Standard
quantum limit
Mass:
Cavity:
Cryostat:
Constraints on the moving mirror
Elimination of technical noises:
No pendular
motion
Large radiation pressure effects:
Reduction of thermal noise:
Working in vacuum and
at low temperature
⇒ Mirrors coated on micro-resonators
Micro-resonators
Micro-fabrication at ESIEE
Optical coating at LMA
Optical metrology at ESPCI
Micro-mirror and cavity
Precise translation mechanism
preserving the parallelism
Experimental setup
䇻 Highly stable
YAG laser source
• High finesse cavity
in vacuum and
thermally stabilized
• Pound-Drever-Hall detection:
⇒ frequency locking
⇒ displacement sensing
• Possibility to apply an electrostatic force:
Thermal noise spectrum at 300 K
Observation of sharp and high mechanical resonances
Sensitivity:
O. Arcizet et al, PRL 97, 133601 (2006)
Optomechanical characterization of a mode
Thermal noise - modulation
Vibration profile
Radiation pressure and mirror dynamics
Cavity detuning induces a binding or
repulsive radiation pressure force
⇒ Optical spring, bistability
Cavity storage time comparable to
mechanical oscillation period
⇒ Optical damping
⇒ Cooling or heating of the mirror
⇒ Parametric instabilities
Optical cooling
Observation of the dynamics on the thermal noise
Negative detunings
Positive detunings
O. Arcizet et al, Nature 444, 71 (2006)
Optical cooling
Observation of the dynamics on the thermal noise
Effective temperature ranging from 10 K to 2000 K
O. Arcizet et al, Nature 444, 71 (2006)
Optical damping
Optical damping for different incident light powers
3.2 mW
2.2 mW
1.6 mW
0.9 mW
0.5 mW
Theoretical curves: optical damping is only due to radiation pressure
Parametric instability
Airy peaks in ϕ − P plane:
Spontaneous oscillation in the unstable domain
with amplitude ~ 10 pm
Conclusion
• Low-loss mirror coated
on a Si micro-resonator
• High-sensitivity displacement
measurement
• First observation of dynamical
effects of radiation pressure:
optical spring, optical damping and parametric instability
Next objectives :
• Low temperature operation
• Observation of quantum effects of radiation pressure