Optimal configurations of filter cavity in future gravitational-wave detectors

TL;DR

This paper evaluates different configurations of filter cavities for future gravitational-wave detectors, finding that Kimble et al's phase filtering scheme offers the best performance for short, practical filter cavities in second-generation detectors.

Contribution

It compares various filter cavity schemes for gravitational-wave detectors and identifies the most effective configuration using numerical optimization.

Findings

Kimble et al's phase filtering scheme is the most promising for short filter cavities.

Numerical optimization supports the superiority of the phase filtering scheme.

Short filter cavities can be effectively used in second-generation detectors.

Abstract

Sensitivity of future laser interferometric gravitational-wave detectors can be improved using squeezed light with frequency-dependent squeeze angle and/or amplitude, which can be created using additional so-called filter cavities. Here we compare performances of several variants of this scheme, proposed during last years, assuming the case of a single relatively short (tens of meters) filter cavity suitable for implementation already during the life cycle of the second generation detectors, like Advanced LIGO. Using numerical optimization, we show that the phase filtering scheme proposed by Kimble et al [Phys.Rev.D 65, 022002 (2001)] looks as the best candidate for this scenario.