Sensitivity of laser gravitational-wave detectors with stable double-pumped optical spring

TL;DR

This paper investigates how stable double-pumped optical springs can enhance the sensitivity of gravitational-wave detectors across a broader frequency range, even with optical losses, and explores applications to advanced detectors like the Einstein Telescope.

Contribution

It introduces a regime with three close eigen frequencies in double optical springs, expanding the frequency band where sensitivity surpasses the Standard Quantum Limit.

Findings

Regime with three close eigen frequencies broadens sensitivity band.

Optical losses do not significantly degrade detector sensitivity.

Potential application to the Einstein Telescope is demonstrated.

Abstract

We analyze the sensitivity of gravitational-wave antenna with stable double optical spring created by two independent pumps. We investigate regime of three close eigen frequencies (roots of characteristic equation) which appears to provide more wide frequency band in which sensitivity of antenna can beat Standard Quantum Limit (SQL) than previously considered regime with two close eigen frequencies. We take into account optical losses and show that they do not degrade sensitivity significantly. We also demonstrate possible application of considered regime to Einstein Telescope.