Noise Estimate of Pendular Fabry-Perot through Reflectivity Change

TL;DR

This paper proposes a method to estimate noise in pendular Fabry-Perot interferometers by monitoring reflectivity changes, which could improve gravitational wave detection accuracy despite long transient behaviors.

Contribution

It introduces a novel approach using reflectivity change points to monitor free oscillations and estimate noise levels in pendular Fabry-Perot systems, emphasizing escape times over full dynamics.

Findings

Effective noise estimation despite long transients

Reflectivity change points correlate with noise levels

Escape times capture key dynamics for gravitational wave detectors

Abstract

A key issue in developing pendular Fabry-Perot interferometers as very accurate displacement measurement devices, is the noise level. The Fabry-Perot pendulums are the most promising device to detect gravitational waves, and therefore the background and the internal noise should be accurately measured and reduced. In fact terminal masses generates additional internal noise mainly due to thermal fluctuations and vibrations. We propose to exploit the reflectivity change, that occurs in some special points, to monitor the pendulums free oscillations and possibly estimate the noise level. We find that in spite of long transients, it is an effective method for noise estimate. We also prove that to only retain the sequence of escapes, rather than the whole time dependent dynamics, entails the main characteristics of the phenomenon. Escape times could also be relevant for future gravitational wave detector developments.