Displacement- and laser-noise-free gravitational-wave detection with two Fabry-Perot cavities

TL;DR

This paper introduces a novel gravitational-wave detection scheme using two Fabry-Perot cavities that eliminates displacement and laser noise, enhancing low-frequency sensitivity compared to previous interferometers.

Contribution

It proposes a new configuration of Fabry-Perot cavities that completely cancels displacement and laser noise in gravitational-wave detection.

Findings

Displacement and laser noise can be fully excluded in the proposed setup.

The response signal decreases as (L/λ_gw)^2 at low frequencies, which is better than previous designs.

The method offers improved sensitivity for gravitational waves with wavelengths much larger than the cavity length.

Abstract

We propose two Fabry-Perot cavities, each pumped through both the mirrors, positioned in line as a toy model of the gravitational-wave (GW) detector free from displacement noise of the test masses. It is demonstrated that the displacement noise of cavity mirrors as well as laser noise can be completely excluded in a proper linear combination of the cavities output signals. We show that in low-frequency approximation (gravitational wave length $\lambda-\text{gw}$ is much greater than distance $L$ between mirrors $\lambda_\text{gw}\gg L$) the decrease of response signal is about $(L/\lambda_\text{gw})^2$, i.e. signal is stronger than the one of the interferometer recently proposed by S. Kawamura and Y. Chen.