Active laser frequency stabilization and resolution enhancement of interferometers for the measurement of gravitational waves in space

TL;DR

This paper introduces an advanced active laser stabilization method for space-based gravitational wave detectors, improving phase noise suppression and measurement resolution by utilizing interferometer arm length differences.

Contribution

It develops an enhanced arm locking technique that incorporates natural arm length differences and existing signals for better laser frequency noise suppression.

Findings

Improved laser frequency stabilization in space interferometers.

Enhanced gravitational wave detection resolution.

Effective suppression of phase noise using the proposed method.

Abstract

Laser frequency stabilization is notably one of the major challenges on the way to a space-borne gravitational wave observatory. The proposed Laser Interferometer Space Antenna (LISA) is presently under development in an ESA, NASA collaboration. We present a novel method for active laser stabilization and phase noise suppression in such a gravitational wave detector. The proposed approach is a further evolution of the "arm locking" method, which in essence consists of using an interferometer arm as an optical cavity, exploiting the extreme long-run stability of the cavity size in the frequency band of interest. We extend this method by using the natural interferometer arm length differences and existing interferometer signals as additional information sources for the reconstruction and active suppression of the quasi-periodic laser frequency noise, enhancing the resolution power of space-borne gravitational wave detectors.