Interferometers for Displacement-Noise-Free Gravitational-Wave Detection

TL;DR

This paper introduces a novel 3D interferometer design for gravitational-wave detection that is free from displacement and laser noise, using four mirrors and two beamsplitters arranged in four Mach-Zehnder setups, with improved low-frequency response.

Contribution

The authors present a displacement- and laser-noise free interferometer configuration that does not require composite mirrors and offers enhanced low-frequency sensitivity compared to previous designs.

Findings

Achieves displacement- and laser-noise free gravitational-wave detection.

Uses a 3D configuration with 4 mirrors and 2 beamsplitters forming 4 Mach-Zehnder interferometers.

Has a low-frequency response proportional to f^2, outperforming previous f^3 responses.

Abstract

We propose a class of displacement- and laser-noise free gravitational-wave-interferometer configurations, which does not sense non-geodesic mirror motions and laser noises, but provides non-vanishing gravitational-wave signal. Our interferometer consists of 4 mirrors and 2 beamsplitters, which form 4 Mach-Zehnder interferometers. By contrast to previous works, no composite mirrors are required. Each mirror in our configuration is sensed redundantly, by at least two pairs of incident and reflected beams. Displacement- and laser-noise free detection is achieved when output signals from these 4 interferometers are combined appropriately. Our 3-dimensional interferometer configuration has a low-frequency response proportional to f^2, which is better than the f^3 achievable by previous 2-dimensional configurations.