First Demonstration of Electrostatic Damping of Parametric Instability at Advanced LIGO

(LSC Instrument Authors)

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Interferometric gravitational wave detectors operate with high optical power in their arms in order to achieve high shot-noise limited strain sensitivity. A significant limitation to increasing the optical power is the phenomenon of three-mode parametric instabilities, in which the laser field in the arm cavities is scattered into higher-order optical modes by acoustic modes of the cavity mirrors. The optical modes can further drive the acoustic modes via radiation pressure, potentially producing an exponential buildup. One proposed technique to stabilize parametric instability is active damping of acoustic modes. We report here the first demonstration of damping a parametrically unstable mode using active feedback forces on the cavity mirror. A 15 538 Hz mode that grew exponentially with a time constant of 182 sec was damped using electrostatic actuation, with a resulting decay time constant of 23 sec. An average control force of 0.03 nN was required to maintain the acoustic mode at its minimum amplitude.

Original languageEnglish (US)
Article number151102
JournalPhysical Review Letters
Volume118
Issue number15
DOIs
StatePublished - Apr 11 2017

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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