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Published April 14, 2017 | Published + Submitted
Journal Article Open

First Demonstration of Electrostatic Damping of Parametric Instability at Advanced LIGO


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.

Additional Information

© 2017 American Physical Society. Received 28 November 2016; revised manuscript received 12 February 2017; published 11 April 2017. The authors acknowledge the entire LIGO Scientific Collaboration for their wide ranging expertise and contributions. LIGO was constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the National Science Foundation, and it operates under Cooperative Agreement No. PHY-0757058. Advanced LIGO was built under Grant No. PHY-0823459. C. B. was supported by the Australian Research Council and the LSC fellows program.

Attached Files

Submitted - 1611.08997.pdf

Published - PhysRevLett.118.151102.pdf


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August 19, 2023
August 19, 2023