Study of Parametric Instability of gravitational wave detectors using silicon test masses

TL;DR

This paper investigates the risk of parametric instability in next-generation gravitational wave detectors using cooled silicon test masses, identifying unstable modes and emphasizing the need for suppression strategies.

Contribution

It provides the first detailed analysis of parametric instability potential in silicon-based gravitational wave detectors, highlighting specific unstable modes and their gains.

Findings

Approximately 2 unstable modes per test mass.

Maximum parametric gain of about 76.

Need for developing instability suppression methods.

Abstract

Parametric instability is an intrinsic risk in high power laser interferometer gravitational wave detectors, in which the optical cavity modes interact with the acoustic modes of the mirrors leading to exponential growth of the acoustic vibration. In this paper, we investigate the potential parametric instability for a proposed next generation gravitational wave detector based on cooled silicon test masses. It is shown that there would be about 2 unstable modes per test mass, with the highest parametric gain of ~76. The importance of developing suitable instability suppression schemes is emphasized.