Resonant Dampers for Parametric Instabilities in Gravitational Wave Detectors

TL;DR

This paper introduces acoustic mode dampers utilizing piezoelectric effects to significantly reduce parametric instabilities caused by high laser power in gravitational wave detectors, improving their stability and performance.

Contribution

The paper presents a novel damper design that effectively suppresses mechanical modes, demonstrated by experimental results on an Advanced LIGO-like test mass.

Findings

10-fold reduction in mechanical mode amplitudes

Effective mitigation of parametric instabilities

Potential for improved detector stability

Abstract

Advanced gravitational wave interferometric detectors will operate at their design sensitivity with nearly 1MW of laser power stored in the arm cavities. Such large power may lead to the uncontrolled growth of acoustic modes in the test masses due to the transfer of optical energy to the mechanical modes of the arm cavity mirrors. These parametric instabilities have the potential of significantly compromising the detector performance and control. Here we present the design of "acoustic mode dampers" that use the piezoelectric effect to reduce the coupling of optical to mechanical energy. Experimental measurements carried on an Advanced LIGO-like test mass shown a 10-fold reduction in the amplitude of several mechanical modes, thus suggesting that this technique can greatly mitigate the impact of parametric instabilities in advanced detectors.