Folding Gravitational-Wave Interferometers

TL;DR

This paper investigates how folding the arm cavities in gravitational-wave interferometers affects their design, revealing that while it doesn't reduce thermal noise, it highlights the folding mirror as a key component for potential upgrades.

Contribution

It introduces the concept of folding arm cavities and analyzes their impact on interferometer design and thermal noise management.

Findings

Folding does not reduce mirror coating thermal noise.

Folding makes the mirror the critical component for upgrades.

Provides new design considerations for gravitational-wave detectors.

Abstract

The sensitivity of kilometer-scale terrestrial gravitational wave interferometers is limited by mirror coating thermal noise. We explore the effect of folding the arm cavities of such interferometers. While simple folding alone does not reduce the mirror coating thermal noise, it makes the folding mirror the critical mirror, opening up a variety of design and upgrade options.