Stabilization of a Fabry-Perot interferometer using a suspension-point interferometer

TL;DR

This paper demonstrates that a suspension-point interferometer can significantly reduce vibrations in a Fabry-Perot interferometer, enhancing its sensitivity and stability for gravitational wave detection.

Contribution

The study introduces a prototype Fabry-Perot interferometer with an integrated suspension-point interferometer for active vibration isolation, showing effective noise reduction.

Findings

Noise spectrum reduced by 40 dB below 1 Hz

Effective vibration suppression above 1 Hz

Improved sensitivity and stability of the interferometer

Abstract

A suspension-point interferometer (SPI) is an auxiliary interferometer for active vibration isolation, implemented at the suspension points of the mirrors of an interferometric gravitational wave detector. We constructed a prototype Fabry-Perot interferometer equipped with an SPI and observed vibration isolation in both the spectrum and transfer function. The noise spectrum of the main interferometer was reduced by 40 dB below 1 Hz. Transfer function measurements showed that the SPI also produced good vibration suppression above 1 Hz. These results indicate that SPI can improve both the sensitivity and the stability of the interferometer.