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Interaction optomécanique à trois modes et refroidissement d'un micro-résonateur mécanique

Abstract : We present a very sensitive optical measurement of the mechanical fluctuations of a micro-mirror in a high finesse Fabry-Perot cavity. The micro-mirror is formed by a micrometric silicon resonator typically oscillating at few megahertz and coated with a high reflectivity dielectrical multilayer. The very high sensitivity of interferometric measurements allows in principle to measure the zero-point fluctuations of the resonator. Its thermal energy becomes negligible with respect to ground state energy when its effective temperature is lower than 30 microKelvin: in order to meet this very stringent condition, we both made use of cryogenic techniques and a cooling laser technique based on dynamical radiation-pressure effects in a detuned cavity. We have thus explored the possibility of performing high-sensitivity optical measurements once the micro-resonator and the cavity are cooled in a flowing helium cryostat. We measured the thermal noise spectrum at cryogenic temperature and realized the radiation pressure cooling of the micro-mirror. We studied a new kind of optomechanical coupling as well, which involves three modes and will enable a more efficient active cooling. We demonstrated the possibility of either increase or decrease the effective temperature, depending on the coupling between the modes. Furthermore, this technique is useful to study the parametric instabilities which are likely to play a role in second generation of gravitational-waves interferometers.
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Contributor : Chiara Molinelli Connect in order to contact the contributor
Submitted on : Wednesday, October 26, 2011 - 2:21:10 PM
Last modification on : Thursday, March 17, 2022 - 10:08:14 AM
Long-term archiving on: : Friday, January 27, 2012 - 2:31:03 AM


  • HAL Id : tel-00635999, version 1


Chiara Molinelli. Interaction optomécanique à trois modes et refroidissement d'un micro-résonateur mécanique. Physique Atomique [physics.atom-ph]. Université Pierre et Marie Curie - Paris VI, 2011. Français. ⟨tel-00635999⟩



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