Effects of Mirror Aberrations on Laguerre-Gaussian Beams in Interferometric Gravitational-Wave Detectors

TL;DR

This paper investigates how mirror surface imperfections affect the performance of higher-order Laguerre-Gaussian beams in gravitational-wave detectors, highlighting limitations and discussing potential mitigation strategies.

Contribution

It demonstrates that mirror aberrations limit the benefits of using higher-order Laguerre-Gaussian modes in reducing thermal noise in interferometers.

Findings

Mirror imperfections reduce the effectiveness of higher-order modes.

Surface aberrations limit thermal noise reduction benefits.

Potential mitigation strategies are discussed.

Abstract

A fundamental limit to the sensitivity of optical interferometers is imposed by Brownian thermal fluctuations of the mirrors' surfaces. This thermal noise can be reduced by using larger beams which "average out" the random fluctuations of the surfaces. It has been proposed previously that wider, higher-order Laguerre-Gaussian modes can be used to exploit this effect. In this article, we show that susceptibility to spatial imperfections of the mirrors' surfaces limits the effectiveness of this approach in interferometers used for gravitational-wave detection. Possible methods of reducing this susceptibility are also discussed.