Reduction of differential phase noise of a power amplifier based on an additional interferometer
Phys. Rev. Applied 23, 064030 – Published 11 June, 2025
DOI: https://doi.org/10.1103/ts2r-tm6f
Abstract
Space-borne gravitational-wave (GW) detectors use a heterodyne laser-interferometry detection scheme due to the influence of relative motion between spacecraft. Accurate tracking of the heterodyne frequency imposes strict requirements on the performance of the spacecraft master clock, and its timing jitter noise is a limiting noise source in the phase measurement. To suppress the clock noise in data preprocessing, an interspacecraft clock-tone transfer chain in the form of phase-modulation sidebands is required. As a main component of this transfer chain, the optical power amplifier introduces excess differential phase noise between the carrier and a sideband. In this paper, we propose a scheme to measure the power amplifier differential phase noise (PADN). For this purpose, an onboard interferometer is designed by mixing the laser after power amplification with the laser before power amplification. We present the corresponding postprocessing PADN cancelation algorithm, which is compatible with the initial noise-reduction pipeline and can be directly applied to any time-delay interferometry variables.
